Biometrics Ltd LABORATORY DATA ACQUISITION SYSTEM OPERATING MANUAL. TYPE NOS. LS900 Including DataLINK DLK900 Software version 5.0

Transcription

1 Biometrics Ltd LABORATORY DATA ACQUISITION SYSTEM OPERATING MANUAL TYPE NOS. LS900 Including DataLINK DLK900 Software version 5.0 This manual should be used in conjunction with Biometrics Ltd Goniometer and Torsiometer Operating Manual Biometrics Ltd EMG Operating Manual Biometrics Ltd Accelerometer Operating Manual DECLARATION Biometrics Ltd trust that you will find everything in order with the equipment you have purchased. In the event that you have any reason for concern, or simply require more detailed advice on the application of your system please do not hesitate to contact us. Please direct any communication to: Biometrics Ltd Cwmfelinfach, Gwent NP11 7HZ UK Tel: Fax: Website: RM

2 CONTENTS PAGE CE Marking 5 Copyright 5 Warnings 5 Electromagnetic Compatibility 6 Help 6 General Description 7 System set-up Installing the Software 11 Hardware Set up 11 OPTION 1. DataLINK connected to a PC. 11 Connecting Multiple DataLINK units 12 OPTION 2. DataLINK not connected to a PC. 13 Connecting Biometrics Goniometers & Torsiometers 14 Connecting Biometrics surface EMG pre amplifier SX Connecting Biometrics 3 Axis Accelerometer ACL Connecting Biometrics Pinchmeter P100 & Dynamometer G Connecting other sensors Sensors with differential voltage outputs 21 Sensors with single ended voltage outputs Connecting the Contact switches FS4 & Event Marker IS2 22 General set up of all analogue & digital channels 22 Maximum Recording Period 22 Connecting Multiple DataLINK Units 23 Programming of Analogue Channels 25 Programming of Digital Channels 27 Start / Stop Recording by other instrumentation 29 Data transfer to disk or to an application 30 Export of Data as ASCII 30 Management & analysis software details of operation 32 File menu 32 Open file 32 Close file 32 Save file 32 Copy graph, graph key & Results to clipboard 32 Export file 32 Export file data format ASCII or Wave 33 Edit menu 33 Set up menu 34 File save mode 34 Analogue inputs 34 Digital inputs 36 Alarms (audible and visual) 37 Save / Load Analogue Channel information 37 Unit Name 38 Y axis & time marker modes 38 FFT High Pass Filters 39 Select graph colour & line width 39 Set up of connection to computer port 39 View menu 39 Recording information 39 Main Toolbar 40 Analysis Toolbar 40 Graph Key 40 Results 41 Markers Time & Data 41 2

3 Calculations 42 Repetitions 42 Excursions 42 Settings 42 Filters Settings Overview using FFT Windowing Functions 43 Rectify 47 Average 47 RMS 47 Velocity 48 Integrate 48 Offset 48 Add Filter 48 Add for Zero Filter 49 Scale 49 Median Frequency 49 Set up FFT High Pass Filter Remove DC 50 Set up FFT High Pass Filter Command 50 FFT Accuracy 50 Mean Frequency Filter 51 Determining the area under a curve 52 Filters Memory 52 Inputs 52 Status Bar 53 Graph Grid Lines 53 Exchange X & Y 53 Log Power Spectrum 53 Zoom menu 53 Transfer menu 53 Window menu 54 Split window 54 New graph 54 Track time axis all windows 54 New Power Spectrum graph 55 New Trace / Trace graph 56 Help menu 56 Example of calculating Work Done during EMG activity 57 Technical Information Application interface functions 59 Microsoft Visual Basic 2005 interface Example 60 Microsoft Visual Basic 6.0 Interface Example 62 Microsoft Visual C Interface Example 62 Microsoft Visual C Interface Example 65 Data transfer protocol 66 USB Communications Overview 66 Protocol command summary & details 67 Stored data format 75 File Formats 76 Symbols 78 Classification 79 Mains Power Supply 79 Mechanical 80 Electrical 80 Environment 82 PC Requirements 82 Cleaning & Disinfection 82 Maintenance 82 Disposal of the equipment 82 3

4 COPYRIGHT 2007 Biometrics Ltd ALL RIGHTS RESERVED NO PART OF THIS DOCUMENT MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC, MECHANICAL OR OTHERWISE, INCLUDING PHOTOCOPYING AND RECORDING IN CONNECTION WITH ANY INFORMATION OR RECORDING SYSTEM, WITHOUT PRIOR WRITTEN PERMISSION FROM BIOMETRICS LTD. PRINTED IN THE UNITED KINGDOM Biometrics Ltd Unit 25, Nine Mile Point Ind. Est. Cwmfelinfach, Gwent NP11 7HZ UK Tel: Fax: North American Toll Free Website: 4

5 CE MARKING All products covered by this manual conform to the Medical Device Directive 93/42/EEC. COPYRIGHT IMPORTANT NOTICE: The software is copyright and may be used only in accordance with the terms of the license you have agreed and entered into upon opening the packet containing your software. WARNINGS When connecting the system to other instrumentation such as personal computers, the resulting medical system must conform to EN :1992 (Collateral Standard: Safety Requirements for Medical Electrical Systems.) All electrical signals connected to the DataLINK Subject Unit must be 20 Vdc / 8 Vac, and must be Safety Extra Low Voltage having Reinforced Insulation from any mains supply. Only the approved Power Supply may be used to power this equipment. Manufacturer:- Mascot Electronics AS, Part No When cleaning or disinfecting the system, the unit must be disconnected from both the power supply and all external instrumentation. When connecting sensors not supplied by Biometrics to the DataLINK an electrical current of no more than 20 ma may be used per channel otherwise damage of the internal circuitry will result. When using all Biometrics Goniometers and Torsiometers care should be taken so that the sensor is only handled and manipulated as instructed. Mishandling may result in reduced life or even failure. Biometrics Ltd accepts no liability or consequential liabilities for the loss, or effects of loss or corruption of data caused by this system. 5

6 ELECTROMAGNETIC COMPATIBILITY The system has been tested for electromagnetic compatibility and was found to comply with European Standard EN :2002. However, within certain environments erroneous readings may be obtained using the equipment due to electromagnetic interference irradiated by certain equipment. If this is experienced then the source of the interference should be located by systematically switching off other electrical equipment in the vicinity where the DataLINK is being used. Once the source of the electromagnetic interference has been located the DataLINK should be used away from this equipment, or this equipment should be switched off and disconnected from the mains supply. Examples of equipment which may be causing problems are laptop computers, mains fluorescent lighting, hand powered tools, other medical equipment etc. If the electrical interference is removed by disconnecting a laptop computer from the mains power supply, then try using the PC powered only from any internal battery pack. In some situations it may be necessary to use the DataLINK system in a different laboratory or building. HELP Should you have problems that cannot be rectified by steps outlined in this manual please contact Biometrics Technical Support at: Biometrics Ltd Unit 25, Nine Mile Point Ind. Est. Cwmfelinfach, Gwent NP11 7HZ UK Tel: Fax: North American Toll Free sales@biometricsltd.com 6

7 GENERAL DESCRIPTION DataLINK is a general purpose subject worn programmable Data Acquisition System allowing the user to collect both analogue and digital data from a wide range of sensors including Biometrics Goniometers, Torsiometers, semg sensors, 3 axis accelerometers, Hand Dynamometer, Pinchmeter and Contact Switches. Examples of other sensor inputs include general load cells, strain gauges, air flow meters, potentiometers, temperature probes, blood pressure meters & microphones. The sensors connect to a small, lightweight Subject Unit with programmable instrumentation amplifiers and individual power supplies responsible for energizing the sensors, sampling and converting the inputs into digital signals. The data is transferred from the Subject Unit to the Base Unit via a RS422 data transfer cable. This cable (type no. R7000) is usually 7 meters in length but may be specified any length up to 20 meters. The Base Unit connects to the host PC using a USB cable where the data may be readily stored on disk as ASCII or passed real time into other applications such as Microsoft Excel or Microsoft Visual Basic using the DLL (dynamic link library). Real time feedback is obtained from the main data display window. Additionally, real time analogue outputs may be obtained using the optional output cable type no. R2000I. DataLINK is available with 8 analogue inputs, accommodating single ended voltage inputs and differential voltage inputs. It comes standard with 5 digital inputs (accessed via 2 sockets which are wired in parallel) and the DataLINK Management Software (Microsoft Windows XP compatible). Optional Analysis Software is available. The DataLINK hardware is primarily digital circuitry, giving a design with the greatest accuracy, negligible drift, and the greatest immunity to noise. Multiple DataLINK units may be used simultaneously for up to 32 channels of data collection. When using multiple DataLINKs, all the data is stored to a single file for analysis. Each input channel is individually configured and controlled within the versatile and easy to use DataLINK Management Software. Options for the analogue inputs include selectable gain, selectable sampling frequency, selectable sensor supply voltage, and selectable zero or datum position. Options for the digital inputs include selectable sampling frequency, threshold level and hysteresis level. 7

8 Overall Design Philosophy The basic design philosophy is to limit the analogue circuitry as much as possible and use digital alternatives. This produces a versatile design with the greatest possible accuracy, negligible drift and greatest immunity to noise. Amplification uses high precision general-purpose digital gain controlled instrumentation amplifiers. Conversion from analogue to digital takes place as early as possible. All calibration and zero operations are performed digitally Excitation output voltages are selected digitally Digital transmission from the remote data-acquisition unit. Isolation provided by digital isolation of the communications link and an isolated DC-DC module. Analogue outputs are provided by converting the digital data from the remote data-acquisition unit. 8

9 DataLINK Subject Unit The Subject Unit is responsible for powering the sensors, sampling and converting the inputs into digital values and communicating with the PC. A separate programmable gain instrumentation amplifier (with a gain of x1, x10, x100 or x1000) processes each analogue-input before passing the input into an 8-way multiplexer. The output from the multiplexer goes into a programmable divide by 1 or 3 and then into a 13-bit ADC. The excitation output voltages in the range of 0V to 4.95V, which are used to power the individual sensors, are generated using a separate 8-bit DAC for each channel. An output current of up to 20 ma per channel is possible. The 5 digital inputs have separate adjustable thresholds for deciding upon a logic 0 or 1; this allows the sensitivity of each input to be matched to the digital sensor as well as providing adjustable hysteresis. High stability components are used throughout so that all of the usual gain and zero adjustments are carried out in software this leads to a design with excellent accuracy and long term drift characteristics. All of the calibration and zero adjustments are stored in EEPROM as well as the settings for such things as gain, sampling rate, excitation output and digital input sensitivity. All communication between the subject unit and the base unit makes use of a bidirectional 115,200 baud RS422 data transfer; this offers high noise immunity when using long connecting cables in electrically noisy environments. 9

10 DataLINK Base Unit M I C R O C O M P U T E R RS422 Driver RS422 Receiver RS422 Receiver RS422 Driver Isolation Isolation Power Isolation USB or RS232 Microcomputer PSU Optional multichannel DAC analogue outputs Optional Digital Outputs digital outputs This interface unit is between the Subject Unit and the PC. Its main features include: A screened cable connecting it to the Subject Unit; this carries power and a bi-directional RS422 link. An isolated DC-DC module. A medical grade external power supply. A USB cable connected to the PC. RS422 PC interface conversion and isolation circuitry. Analogue outputs. Digital outputs. The analogue outputs are single ended with a nominal full-scale range of +0V to +4V; an analogue value of zero produces an output of 2V. The digital outputs are 0V to 5V with a source impedance of 1k ohms. 10

11 SYSTEM SET-UP INSTALLING THE SOFTWARE CD ROM 1. Insert the Biometrics DataLINK CD into your CD ROM drive. 2. The installation process should start automatically within a few seconds. If this does not happen, go to RUN under the START menu and type in d:\setup. 3. Follow the prompts to complete the installation. HARDWARE SET UP OPTION 1. DataLINK connected to the PC. The DataLINK hardware consists of two main units and some connecting cables. STEP 1. Connect the DataLINK Subject Unit to the Base Unit using cable type no. R7000. STEP 2. Connect the external mains power supply to the Base unit. Plug the power supply into a mains socket and switch the mains socket on. The power LED on the front of the Base Unit will light continuously. 11

12 NOTE: Only the approved Power Supply may be used to power this equipment. Manufacturer: - Mascot Electronics AS, Part No STEP 3. Connect the DataLINK Base Unit to a USB port of the host PC using cable type no. USB1800. STEP 4. Launch the DataLINK software application. The USB LED will light continuously and then will flash repeatedly to indicate that the PC has recognised the DataLINK hardware. Subsequent flashing is normal and indicates that the PC application is accessing DataLINK. HINT: If the unit does not communicate successfully with the PC within a few seconds, from the >Set-up menu located towards the top left of the screen, go to >Port and check that it is set to USB. Note: for multiple DataLINKs repeat step 1 to 3 for each DLK900. Two, three, and four DataLINK DLK900 systems may be connected to allow 16, 24, or 32 channels of data collection. Due to the complexity of simultaneously using multiple USB drivers it may be necessary to try different USB ports on the same PC to allow communications and data transfer. Note that when the DataLINK System has been configured, all of these setting are saved within the DataLINK Subject Unit and will be retained even when power is removed. When using multiple DataLINKs, all the data is saved in a single file. STEP 5. If the option is required to have analogue output voltages for each channel, connect the optional output cable type no. R2000I to the Base Unit. The DataLINK is now ready for connection of the sensors. Configuring Multiple DataLINK units When connecting multiple DLK900, each unit is individually configured and the configuration is saved within that unit. Whilst the configuration is specific to each unit, the data collected is saved as a single file. Each DataLINK unit is assigned a name that is stored within the unit. The name may be changed by the user at any time by using the UNIT NAME command under the SETUP menu. Use the CONNECTED UNITS command under the VIEW menu to open the CONNECTED UNITS window or click TOGGLE CONNECTED UNITS from the 12

13 toolbar. Switch between the connected units by clicking on the desired unit in the window. In order to maintain screen clarity and uniformity when operating more than one unit, all screen windows, displays and dialogues show one DataLINK unit at a time. The unit that is referred to is displayed in the title bar and highlighted in the CONNECTED UNITS window. OPTION 2. DataLINK not connected to the PC. The DataLINK may be set up and used independent of the PC where analogue voltages are obtained using the cable type no. R2000I. If this option is chosen the unit will continuously transmit at 5000 samples per second on all analogue and digital channels using the analogue and digital channel set ups (including individual channel zero positions) which were selected the last time the unit was connected to the PC. STEP 1. Connect the DataLINK Subject Unit to the Base Unit using cable type no. R7000. STEP 2. Connect the external mains power supply to the Base Unit. Plug the power supply into a mains socket and switch the mains socket on. The power LED on the front of the Base Unit will light continuously. NOTE: Only the approved Power Supply may be used to power this equipment. Manufacturer: - Mascot Electronics AS, Part No STEP 3. Connect the output cable type no. R2000I to the Base Unit. An analogue output voltage may now be obtained for each channel. If the set up of any channel needs to be changed including the zero, the unit must be connected to a PC as described above in option 1. Note: For multiple DataLINKs repeat steps 1 to 3 for each DLK900. Two, three, and four DataLINK DLK900 systems may be connected to allow 16, 24, or 32 channels of data collection. The DataLINK is now ready for connection of the sensors. 13

14 CONNECTING BIOMETRICS GONIOMETERS AND TORSIOMETERS SG Series Goniometers Q Series Torsiometers Connect the sensors across the joints under investigation as indicated in the Goniometer and Torsiometer Operating Manual. CARE SHOULD BE TAKEN SO THAT THE SENSORS ARE ONLY HANDLED AND MANIPULATED AS INSTRUCTED. MISHANDLING MAY RESULT IN REDUCED LIFE OR EVEN FAILURE. For each channel connect the black socket of the J1000 lead to the black plug of the sensor ensuring that the polarisation marks are aligned before insertion. Connect the silver plug of the J1000 lead to one of the input sockets of the DataLINK Subject Unit. Ensure that the red marks are aligned and push the plug until it engages with a click. The plug is of a self-latching type and cannot be disconnected by pulling on the cable. To remove the plug hold the outer case and pull until it disengages. For each channel with a Biometrics Goniometer or Torsiometer attached, select the goniometer default from within the Channel Configuration Dialogue which will set the channel up as follows:- Channel sensitivity goniometer Sampling rate 200 Excitation Output 2000 mv Zero Full scale Units The real time display within the Data Display Window and all the corresponding graph traces will default to degrees angle. When using Biometrics Goniometers and Torsiometers the displayed output is -180 to +180 degrees. 14

15 CONNECTING BIOMETRICS SURFACE EMG PRE AMPLIFIER SX230. EMG Pre Amplifier SX230 Earthing Strap R206 Adhesive Pads T350 (350 pieces) EMG measurements can be taken with the DataLINK along with up to 8 EMG probes. Prepare the area of skin where the probes will be attached by washing with proprietary skin soap making certain to dry the area thoroughly. Also prepare the area of skin which will come into contact with the elastic ground strap in the same manner. Apply the SX230 over the body of the muscle using the die cut medical grade double sided adhesive tape (part no. T350). Due to the superb quality of the SX230 electronics, with this little skin preparation, an ultra high quality signal is obtained without the use of conductive gels or creams. Attach the R206 ground reference cable to the subject using the wrist band provided and attach the other end to either of the digital sockets of the DataLINK Subject Unit. HINT: Make certain that the elastic wrist band is secured firmly to obtain a good ground. The lack of a good ground is by far the most common problem when trying to secure EMG readings with a high signal to noise ratio. NOTE THAT THE SILVER PLUG OF THE R206 CABLE MAY ONLY BE CONNECTED TO THE DIGITAL SOCKET OF THE DATALINK SUBJECT UNIT. DO NOT ATTEMPT TO CONNECT IT TO ANY OF THE ANALOGUE INPUT SOCKETS AS THIS MAY DAMAGE THE PLUG. From within the host software open the analogue set up dialog box. For the channel with the Active Probe SX230 connected select the EMG preset default which will set up the channel as follows:- Channel sensitivity 3 Vdc Sampling rate 1000 Excitation Output 4950 mv Zero 0 Full scale 3 Units mv 15

16 HINT: If the waveform is smaller than about 30% of full scale, try increasing the channel sensitivity as shown below to observe these smaller EMG waveforms: For the channel with the Active Probe SX230 connected select the following settings:- Channel sensitivity 1 Vdc Sampling rate 1000 Excitation Output 4950 mv Zero 0 Full scale 1 Units mv Or Channel sensitivity 300mV Sampling rate 1000 Excitation Output 4950 mv Zero 0 Full scale 300 Units µv It is possible to use sampling rates higher than 1000 / sec but nothing will be gained as the EMG probe is frequency limited. Using sampling rates lower than 1000 / sec is not recommended, as the higher EMG frequencies will be converted to lower frequency interference that will distort the waveforms. A good zero may be taken without a probe attached to avoid the effect of noise pickup on the zero. Some experimentation is usually necessary to obtain the best EMG waveforms but the following guidelines may be helpful:- The electrode should be placed along the midline of the muscle with the two electrodes in line. The R206 common or ground electrode (sometimes called a reference electrode) is necessary to provide a reference for the differential inputs and to cancel the electrical interference on the skin. This electrode is provided as a wrist strap and should be placed some distance away from the probe on electrically neutral tissue such as over a bony area. The R06 common or ground electrode must make as good a contact with the skin as possible. Always be aware of line-frequency pickup. Use the Frequency Analysis display to check for disproportionate amounts of signal at 50/60Hz. NOTE: For an example of calculating Work Done during EMG activity, refer to page

17 CONNECTING BIOMETRICS 3 AXIS ACCELEROMETER ACL300 The ACL300 is a precision accelerometer providing a complete ready to go solution for measurements of acceleration in 3 axes. The ACL300 is ideal for multiple research applications as it comes with adjustable low pass filter settings standard at 100Hz, 500Hz and 1000Hz. ACL300 Active probe dimensions 19 x 12 x 11 mm Connect the 3 silver 4-pin plugs of the ACL300 to 3 analogue channels of the DataLINK. For ease of use we suggest that the following configuration is adhered to although this is not necessary:- DataLINK analogue channel ACL300 channel 1 X 2 Y 3 Z Ensure that the red alignment marks on both plug and socket are aligned and push until they engage with a click. The plugs are of a self-latching type and cannot be disconnected by pulling on the cable. To remove the plugs hold the outer case and pull until they disengage. NOTE: The ACL300 receives all the power required for operation through the X channel plug. Therefore if only 1 channel of operation is required this must be channel X or the unit will not function. If 2 channels are required these may be channels X & Y, or channels X & Z. 17

18 For each channel with the accelerometer attached, select the accel default from within the Channel Configuration Dialogue. This default setting will be as follows:- Channel enable check so that a black check is visible Channel title type in as appropriate (e.g. Accel X, Accel Y etc.) Channel sensitivity ± 1 V Sampling rate user select (refer to bandwidth considerations below) Excitation output 4500 mv Zero 0 Full Scale 10 (or 98.1) Units G (or m/s/s) ( units may be displayed as gravity G or m/s 2 ) Note:- the above set up will give a resolution of G. For higher resolution please refer to the accelerometer operating manual. DATUM SETTING OR ZEROING To set up and zero the ACL300 place the active probe on a flat surface perpendicular to the earth s gravity with the black XYZ label visible on the upper surface. The probe must be stationary. Using the host software, from within the analogue set up dialogue box, press the zero button for each channel and then press enter to zero all 3 channels. The ACL300 is now ready for use. 18

19 CONNECTING BIOMETRICS PINCHMETER P100 & HAND DYNAMOMETER G100. Pinchmeter P100 The Biometrics isometric Pinchmeter P100 & isometric Hand Dynamometer G100 are both connected to any analogue channel of the DataLINK using cable type no. H1800. Connect the 7-pin plug of the H1800 cable (incorporating black flexible sleeve) to either the P100 or G100. Connect the silver 4-pin plug of the H1800 cable to one of the analogue input sockets of the DataLINK. With both plugs ensure that the red marks on both plug and socket are aligned and push until they engage with a click. The plugs are of a self-latching type and cannot be disconnected by pulling on the cable. To remove the plugs hold the outer case and pull until they disengage. From within the host software open the analogue set up dialog box. For the channel with the Pinchmeter P100 connected select the P100 preset default which will set up the channel as follows:- Channel sensitivity 3 mvdc Sampling rate user select Excitation Output 2000 mv Zero 0 Full scale 50 (Units lbs) or (Units Kg) Units lbs or Kg (refer to above) With no load applied to the pinchmeter select the channel zero button and press enter to zero the device. The pinchmeter is now ready for use. 19

20 Dynamometer G100 From within the analogue set up dialog box, for the channel with the Dynamometer G100 connected, select the G100 preset default which will set up the channel as follows: Channel sensitivity 3 mvdc Sampling rate user select Excitation Output 2120 mv Zero 0 Full scale 200 (Units lbs) or 90.7 (Units Kg) Units lbs or Kg (refer to above) With the dynamometer in the vertical position as shown above and with no load applied select the channel zero button and press enter to zero the device. The dynamometer is now ready for use. 20

21 CONNECTING OTHER SENSORS The DataLINK is a general purpose A/D interface and has been designed specifically to give the user the greatest flexibility when connecting a variety of sensors. Proceed as follows:- Sensors with Differential Outputs Connect the sensor to cable type no. D1500 following the wiring code as shown below:- Wire Colour Red Green Blue Yellow Description Positive supply Common or Ground Positive differential output Negative differential output Connect the cable and sensor assembly to the DataLINK Subject Unit and program the channel set-up from the Channel Configuration Dialogue. Set datum or zero position Select the most appropriate gain setting Select the supply voltage NOTE: IT IS IMPORTANT THAT NO MORE THAN 20 ma IS USED PER CHANNEL OTHERWISE DAMAGE OF THE INTERNAL CIRCUITRY WILL RESULT. Sensors with Single Ended Outputs Connect the sensor to cable type no. D1500 following the wiring code as shown below:- Wire Colour Description Red Green Blue Yellow Positive supply Common or Ground Positive output Connect to Common (green) Connect the sensor to the DataLINK Subject Unit and program the channel set-up from the Channel Configuration Dialogue. Set datum or zero position Select the most appropriate gain setting Select the supply voltage NOTE: IT IS IMPORTANT THAT NO MORE THAN 20 ma IS USED PER CHANNEL OTHERWISE DAMAGE OF THE INTERNAL CIRCUITRY WILL RESULT. 21

22 CONNECTING THE CONTACT SWITCHES & EVENT MARKER The DataLINK provides 5 digital channels which are accessed via 2 sockets on the Subject Unit wired in parallel. The Contact Switch assembly type no. FS4 and the Event Marker type no. IS2 may be connected to the DataLINK using either of these sockets. EVENT MARKER IS2 A 1.8 meter cable with a suitable connector at one end to connect to the DataLINK Subject Unit, and a hand held switch at the other. This useful accessory allows time marks to be placed on the recorded data enabling the operator to highlight specific events during data collection. It may also be set-up to start and stop recording. CONTACT SWITCH ASSEMBLY FS4. An assembly of 4 Force Sensing Resistor Sensors (FSRs) each on 1.2 meters of cable. The switches are connected to the DataLINK Subject Unit using one plug for use as contact switches e.g. monitoring heel and toe strike or palmer contact. The sensors are thin and robust and are usually placed inside the subject s shoe or glove for convenience. GENERAL SET UP OF ALL ANALOGUE & DIGITAL CHANNELS. If multi-channel data is to be analysed using a spreadsheet or other application then it may be easier to use the same sampling rate on all channels. Maximum Recording Time The maximum recording time is dependent on the amount of memory available. The number of megabytes assigned to all DataLINK units determines the maximum length of time that can be recorded according to the following rules for each unit. 1. Add together the total number of samples per second for each enabled channel (the digitals, if included, count as one channel). 2. Multiply this by 2 to get the number of bytes per second. 3. Multiply the number of bytes per second by the required recording length in seconds. This gives the number of bytes required for a recording. 22

23 To increase or decrease the recording memory size open the OPTIONS window under the SETUP menu. An estimate of the maximum recording time available with the current settings for each DataLINK unit attached is displayed. Setting too high a value for recording memory may result in an insufficient memory warning when starting a transfer. Too low a value obviously limits the recording time possible. The maximum values that can be set depend upon the available RAM in the PC as well as the configuration of virtual memory within Windows. Using more than one DataLINK unit multiplies the RAM requirements proportionally. Connecting Multiple DLK900 A single DataLINK unit is capable of recording up to 8 analogue channels; if more than 8 channels are required, two or more USB DataLINK units may be operated together. Recordings can be created that can have up to four units (up to 32 analogue channels). When connecting multiple DLK900, each unit is individually configured and the configuration is saved within each individual DLK900 for that DLK900. While the configuration is specific to each unit, the data collected is saved as a single file. A DataLINK unit is assigned a user-defined name that is stored within the unit. This may be changed at any time using the Set-up Unit Name Command from within the View Menu. In order to maintain screen clarity and uniformity when operating more than one unit, all screen windows, displays and dialogues show one DataLINK unit at a time. The unit that is referred to is usually displayed in the title bar and highlighted in the Connected DataLINK Units Window. The following hints may be useful when recording with several DataLINK units:- A recording can only be made using all of the DataLINK units shown in the Connected DataLINK Units Window. Of course, any or no channels can be enabled for each unit. Each unit may be individually configured using the Set-up Analogue Inputs Dialogue and the Set-up Digitals Dialogue. Better real-time screen displays are produced by setting the Auto Tile on Transfer option in the Set-up Options Dialogue. Start and stop data transfer in the normal way. 23

24 During transfer, the active display DataLINK unit may be selected by clicking inside the Connected DataLINK Units Window or clicking within one of the real-time display windows. The Graph Key, Graph Settings, Results and Input Values window contents change to reflect the active display unit selected. During transfer, vertical zoom in and out are active. After transfer in file-save mode, the real-time windows change to linked waveform windows. Operations such as scrolling, time zooming, marking, selection delete, saving and closing operate on all linked windows as though they are a single recording. Note that all linked windows into a recording share a unique leading reference number at the left of the title bar even when minimised. The maximum recording time is totally dependent upon the amount of memory available. Some tuning of the memory to make available to for recording may be necessary in the DataLINK Set-up Options Dialogue. Starting any DataLINK unit using a start/stop recording switch produces a synchronised recording from all units. Note that due to USB synchronisation issues, it is not possible to start one unit any closer than 10mS from any other. 24

25 Programming of Analogue Channels Channel Configuration Dialogue Channel Enable A mark in a channel enable checkbox means that data will be collected for that channel when the record command is given. Channel Title Each analogue input channel can have a user-defined title to help identify what kind of data the display is showing. Channel Sensitivity If a Biometrics sensor is connected to a channel input then that channel sensitivity must be set to the appropriate preset. If the channel is used for voltage measurement, the input sensitivity must be set to the voltage that should produce the maximum digital output of The input range is bipolar and therefore produces a digital output of with an input that is -(input sensitivity). For example, the 1mV sensitivity range produces a value of 4000 for an input of 1mV and for an input of -1mV. Set Zero When the set zero button is pressed for any channel, an operation is performed to set the digital output to zero. 25

26 Sampling Rate The analogue input voltage received on a channel is converted into a digital numbers many times a second. How many times per second this conversion takes place is the sampling rate and this may be set from here. The higher the sampling rate, the more accurately a fast moving signal can be captured. Too high a sampling rate however, results in large quantities of data that does not change very often. NOTE: if multi-channel data is to be analysed using a spreadsheet or another application, it may be easier to use the same sampling rate on all channels. Excitation Output Each analogue channel input connector has a DC excitation voltage output. This output is primarily designed to be used as a bridge supply voltage. Although the output voltage may be set to a number of millivolts, the resolution of the output is about 20mV over a range of 0V to about 4950mV. Although a very stable output, its accuracy is about +/-2%. Display Value and Units The zero and full-scale values control the conversion from the +/-4000 raw value input into engineering units such as Kg or psi. They are not enabled for goniometer inputs as these inputs always display in degrees of arc. When a data value of zero is input, the value shown in the Zero box will be displayed. When a positive full-scale input is measured, the value shown in the Full-scale box will be displayed. All other inputs will be calculated using these two values in a linear relationship. The Units box allows the engineering unit text to be entered. Note the zero, full scale and units only have an effect when the optional analysis software is used. The conversion and the units information is stored in the DataLINK. Preset Selecting one of the presets from the drop down list and pressing the Preset button will configure the channel for operation with a particular Biometrics sensor. After selecting a preset, any channel parameter can still be altered to suite the requirements of the measurement; the channel sensitivity for EMG for example, may be changed to observe very small EMG waveforms. Apply Pressing this button transfers the values from the dialogue into the DataLINK hardware for immediate effect. It is the same as pressing the OK button but without closing the dialogue. Zero All Pressing this button will perform a zero operation on all analogue channels simultaneously. 26

27 Set Defaults Pressing this button copies default values into all of the boxes in the dialogue. These values will not be used unless the Apply or OK button is pressed. Programming of Digital Channels Digital Inputs Configuration Dialogue This dialogue controls the operation of the 5 digital inputs and the start/stop input. A voltage input of +5V is equivalent to logic 1, and a voltage input of +0V is equivalent to logic 0. 1 if Above The digital input will register logic 1 if the voltage generated on the input goes above this percentage of 5V. The logic 1 will remain until the input voltage goes below the Digital 0 value; this provides some hysteresis to counteract the effect of input noise. 0 if Below The digital input will register logic 0 if the voltage generated on the input goes below this percentage of 5V. The logic 0 will remain until the input voltage goes above the Digital 1 value; this provides some hysteresis to counteract the effect of input noise. 27

28 Display Weighting A pair of digital inputs are used to produce each trace displayed within the host software. The trace has a vertical range of 0 to 3 which is the result of adding two digital inputs with a binary weighting as follows: Input 1 Input 2 Trace value with weighting 1 2 Trace value with weighting Programmable Input Active Edge The Programmable input would normally be connected to a switch between the input and 0V. This control allows the active edge for this input to be defined. If 0 to 1 is selected, an event is generated when the digital input changes from logic 0 to logic 1; a 1 to 0 transition is ignored. If 1 to 0 is selected, an event is generated when the digital input changes from logic 1 to logic 0; a 0 to 1 transition is ignored. Programmable Input Function The Programmable input can perform 2 different functions: Event Marker. A vertical line on the digital trace indicates an active event-marker edge. Note that the digital inputs MUST be enabled for event markers to work. Start/Stop Transfer. An active edge will start data transfer to disk or, if transfer is already taking place, an active edge will stop data transfer. Note that the digital inputs do not need to be enabled for this function to work. Enable Digital Recording When checked, the 5 digital channels will be recorded. The record enable checkbox and the sample rate list box are the same as those found in the Set-up Analogue Inputs dialogue. Digital Sampling Rate This sets the number of samples to be recorded every second. Apply Pressing this button transfers the values from the dialogue into the hardware for immediate effect. It is the same as pressing the OK button but without closing the dialogue. Set Defaults Pressing this button copies default values into all of the boxes in the dialogue. These values will not be used unless the Apply or OK button is pressed. 28

29 START / STOP BY OTHER INSTRUMENTATION The Start recording and Stop recording function of the DataLINK may be activated by another instrument which has the ability to switch a TTL signal, i.e. the ability to switch a signal line from logic 1 (+5 V) to logic 0 (+0 V) or visa versa, from logic 0 (+0 V) to logic 1 (+5 V). The signal is interfaced to the DataLINK using SYNCHRONISATION CABLE type no. SYNC1. The silver plug is connected to either digital input socket of the DataLINK Subject Unit. At the other end of the cable are 2 wires coloured red and black. Red wire is common or ground. Black wire is normally logic 1 or +5Vdc The appropriate connector is attached to these wires for correct connection to the 3 rd party instrument following all necessary instructions. IMPORTANT All electrical signals connected to the DataLINK Subject Unit must be 20 Vdc / 8 Vac, and must be Safety Extra Low Voltage having Reinforced Insulation from any mains supply. HINT: 1. Within the software application from within the Digital Inputs Dialogue box the Function option must be set to Start/Stop Transfer. 2. The switching function may be achieved by momentarily shorting the red wire to the black wire. 3. From within the Digital inputs Dialogue box the Active Edge option may be selected such that switching occurs when the TTL is switched to high logic 1 (+5V) OR low logic 0 (+0V). 4. Although the SYNC1 cable may be used to synchronise the start and stop recording function, the stop function is of less importance. The cable should be temporarily connected at the commencement of data collection and then removed to make way for other devices. SYNCHRONISATION CABLE type no. SYNC1BNC. A synchronisation cable with a BNC connector fitted for interfacing to certain 3 rd party systems. Connector chassis is wired as common or ground. NOTE:- Please contact Biometrics Ltd or the 3rd party equipment manufacturer for specific instructions before this cable is used. 29

30 DATA TRANSFER TO DISK OR TO AN APPLICATION. From within the software using the above icon situated on the main toolbar, the following 2 options for transferring data may be selected:- DATA SAVE TO FILE MODE Set the mode to File Save. Note that the open file icon will have become activated as shown above. Allows you to open a new window and start collecting data to a file. After data transfer has been started in this mode, all of the data received is stored in the memory of the PC. DATA TRANSFER TO APPLICATION Set the mode to Data Transfer. Note that the open file icon is now greyed out as shown above. Allows you to open a new window and start transferring data to another application. After data collection has been started in this mode, all of the data received is temporarily buffered in the memory of the PC ready to be read by another application using eth dynamic link library (DLL). It is not possible to use the file saving facility when operating in this mode. EXPORT OF ANALOG DATA AS ASCII The DataLINK has a 13 bit front end ADC giving a full scale input of +/ counts. When the data is exported as ASCII the input value corresponding to when the zero key is pressed is always 0 count, and the full scale input is measured from this value +/ counts. ASCII values using Biometrics Goniometers & Torsiometers. Using the default settings for goniometer within the analogue set up dialog box, +/ counts equals +/- 180 degrees angle. e.g. an ASCII value of equates to an angle of (3000/4000)*180 Degrees = degrees. ASCII values using Biometrics SX230 Active EMG Probe. Using the default settings for EMG within the analogue set up dialog box, +/ counts equals +/- 3 mvdc 30

31 e.g. an ASCII value of equates to a muscle signal of (3000/4000)*3 mvdc = mvdc. ASCII values using Biometrics ACL300 3 axis Accelerometer. Using the default settings for the ACL300 within the analogue set up dialog box, +/ counts equals +/- 10G e.g. an ASCII value of equates to an acceleration of (3000/4000)*10 G = G. ASCII values using Biometrics Dynamometer G100. Using the default settings for the dynamometer type no. G counts equals Kg. e.g. an ASCII value of equates to an angle of (3000/4000)* Kg = Kg. EXPORT OF DIGITAL DATA AS ASCII The 4 digital inputs (labelled ABCD) are exported in ASCII as a 2 digit array as follows: A 29 B 28 AB 27 C 26 AC 25 BC 24 ABC 23 D 22 AD 21 BD 20 ABD 19 CD 18 ACD 17 BCD 16 ABCD 31

32 MANAGEMENT & ANALYSIS SOFTWARE DETAILS OF OPERATION File Menu The File menu offers the following commands: Open This command opens a disk file holding a complete recording. Once opened, the data may be displayed, analyzed, or exported in ASCII or Wave form. Close Close all windows of the current data file. Close All Close all windows of all data files. Save As Save the file to disk. Graph to Clipboard Copy the current window to the clipboard as an Enhanced Metafile. This may be pasted into other applications such a Microsoft Word and scaled to the desired size. Key to Clipboard Copy the graph key for the current window to the clipboard as an Enhanced Metafile. This may be pasted into other applications such a Microsoft Word and scaled to the desired size. Results to Clipboard Copy the total results for the current window to the clipboard as an Enhanced Metafile. This may be pasted into other applications such a Microsoft Word and scaled to the desired size. Export This command exports data into a specified file. Before the file name can be specified, a dialogue box opens to allow the Export Data File Format to be configured. The data may be exported as an ASCII file, or data from one or two channels may be exported into a single disk file in a standard sound Wave file format. After specifying the data file format, a dialogue provides options to allow you to specify the name and location of the file you're about to save. Export Data Format This dialogue determines the amount and format of the data that will be exported to a disk file. Note that exporting some or all of the data to a disk file does not erase that data - the data may therefore be exported any number of times until new data is collected. 32

33 Data may be exported in one of two formats: ASCII The data from one or more channels may be exported into a single disk file as a series of ASCII numbers. The data is output as one or more values on a line with the values on the line separated by the delimiter character indicated in this dialogue. If data from more than one channel is saved then each line of the output file will contain one value from each channel. If data from a single channel is saved then the number of values on each line may be chosen in the range of 1 to 256. The numbers shown in brackets after each channel selection box indicate the number of values that will be saved for that channel. Wave The data from one or two channels may be exported into a single disk file in a standard sound Wave file format. The data may then be read by a number of soundanalysis programs such as "Cool Edit". If one channel is selected, a mono file is saved; if two channels are selected, a stereo file is saved. The Wave file contains information describing the sampling rate used. Since not all applications can input the range of sampling rates used by a channel, the Force to 8kHz check box is available to override the saved sampling frequency and permit any wave compatible application to load the data file. Exit Use this command to exit from the application. You can also use the Close command on the application Control menu. The program will prompt you to save any unsaved data. Edit Menu Delete Trace Command Delete the trace selected in the Results Box. This completely removes the trace but does not affect any data previously saved to disk. Delete Digitals Command The Edit menu offers the following commands: Delete all digital traces. This completely removes the traces but does not affect any data previously saved to disk. Delete Selection Command Delete the marked time from all traces. This completely removes the marked time but does not affect any data previously saved to disk. 33

34 Set-up Menu The Setup menu offers the following commands: File Save Mode Allows selection between the following 2 modes:- Start Data Transfer to Disk Allows you to open a new window and start collecting data to a file. (the file open icon in the main toolbar will not be greyed out but will be accessible). Start Data Transfer to Application Allows you to open a new window and start transferring data to another application. (the file open icon in the main toolbar will be greyed out). Analogue Inputs Channel Enable A mark in a channel enable checkbox means that data will be collected for that channel when the record command is given. Channel Title The channel titles are typed in by the user and are saved in the DataLINK and relate to all recordings held in the DataLINK. Channel Sensitivity If a Biometrics sensor is connected to a channel then the appropriate preset button should be selected to configure the channel for operation. If the channel is used for voltage measurement, the input sensitivity must be set to the voltage that should produce the maximum digital output of The input range is bipolar and therefore produces a digital output of with an input that is -(input sensitivity). For example, the 1mV sensitivity range produces a value of 4000 for an input of 1mV and for an input of -1mV. Set Zero When any value is applied to a channel input, pressing this button will perform a zero operation to produce a digital output of zero. If an input voltage is more than about 2% away from zero, an attempt will still be made to produce an output of zero. However, this may result in the range of digital values available being less than to

35 Sampling Rate The analogue input voltage received on a channel is converted into a digital number many times a second. How many times per second this conversion takes place is the sampling rate and this may be set from here. The higher the sampling rate, the more accurately a fast moving signal can be captured. Too high a sampling rate however, results in large quantities of data that does not change very often. HINT. Always try to use the lowest channel numbers for the fastest sampling; for example, channel 1 at 5kHz and channel 2 at 1kHz rather than channel 2 at 5kHz and channel 1 at 1kHz. This removes time-jitters during recording and gives the best signal recording accuracy. Excitation Output Each analogue channel input connector has a DC excitation voltage output. This output is primarily designed to be used as a bridge supply voltage. Although the output voltage may be set to a number of millivolts, the resolution of the output is about 20 mv over a range of 0V to 4950 mv. Although a very stable output, its accuracy is about +/-2%. Display Value and Units The zero and full scale values control the conversion from the +/-4000 raw value input into engineering units such as Kg or psi. They are not enabled for goniometer inputs as these inputs always display in degrees of arc. When a data value of zero is input, the value shown in the Zero box will be displayed. When a positive full-scale input is measured, the value shown in the Full-scale box will be displayed. All other inputs will be calculated using these two values in a linear relationship. The Units box allows the engineering unit text to be entered. Note the zero, full scale and Units only have an effect when the analysis software is used. The conversion and the Units information is stored in the DataLINK and relates to all recordings held in that DataLINK. Preset Selecting one of the presets from the drop down list and pressing the Preset button will configure the channel for operation with a particular Biometrics sensor. After selecting a preset, any channel parameter can still be altered to suite the requirements of the measurement. Apply Pressing this button transfers the values from the dialogue into the DataLINK hardware for immediate effect. It is the same as pressing the OK button but without closing the dialogue. Zero All Pressing this button will allow the zeroing of all analogue channels simultaneously. 35

36 Set Defaults Pressing this button copies default values into all of the boxes in the dialogue (referring to a Biometrics goniometer connected to all 8 analogue channels sampling the data at 200 Hz per channel). These values will not be used unless the Apply or OK button is pressed. Digital Inputs This dialogue controls the operation of the 5 digital inputs and the start/stop input. 1 if Above The digital input will register logic 1 if the voltage generated on the input goes above this percentage of 5V. The logic 1 will remain until the input voltage goes below the Digital 0 value; this provides some hysteresis to counteract the effect of input noise. 0 if Below The digital input will register logic 0 if the voltage generated on the input goes below this percentage of 5V. The logic 0 will remain until the input voltage goes above the Digital 1 value; this provides some hysteresis to counteract the effect of input noise. Enable Digitals When checked, the four digital channels will be recorded. The record enable checkbox and the sample rate list box are the same as those found in the Set-up Analogue Inputs dialogue. Digital Sampling Rate This sets the number of samples to be recorded every second. The record enable checkbox and the sample rate list box are the same as those found in the Set-up Analogue Inputs dialogue. Active edge The Programmable input would normally be connected to a switch between the input and 0V. This control allows the active edge for this input to be defined. If 0 to 1 is selected, an event is generated when the digital input changes from logic 0 to logic 1; a 1 to 0 transition is ignored. If 1 to 0 is selected, an event is generated when the digital input changes from logic 1 to logic 0; a 0 to 1 transition is ignored. Programmable Input Function The Programmable input can perform 2 different functions: Event Marker. A vertical line on the digital trace indicates an active event-marker edge. Note that the digital inputs MUST be enabled for event markers to work. Start/Stop Transfer. An active edge will start data transfer to disk or, if transfer is already taking place, an active edge will stop data transfer. Note that the digital inputs do not need to be enabled for this function to work. 36

37 Start/stop Recording Input The start/stop input performs an action when the input changes from logic 1 to logic 0. When this input is unconnected, it is at logic 1. When the DataLINK is showing a menu that includes "Record", a 1 to 0 on the start/stop input will begin recording. The next 1 to 0 on the start/stop input will stop the recording. Apply Pressing this button transfers the values from the dialogue into the hardware for immediate effect. It is the same as pressing the OK button but without closing the dialogue. Set Defaults Pressing this button copies default values into all of the boxes in the dialogue. These values will not be used unless the Apply or OK button is pressed. Alarms This dialogue allows the upper and lower alarm levels to be configured for all 8 analogue channels using engineering units. If a lower alarm is enabled and the analogue input falls from above the level to below the level, an audible alarm is produced by the DataLINK, and the background colour changes to blue. If an upper alarm is enabled and the analogue input rises from below the level to above the level, an audible alarm is produced by the DataLINK, and the back ground colour changes to red. Alarm colour changes stay for at least 0.3 seconds. Consequently, a high and low alarm may be indicated simultaneously as a combination of the two alarm colours. Unit Set-up Save / Load This dialogue allows the user to readily save and load user defined parameters within the analogue set-up dialogue box. e.g. 8 channels set-up for goniometry, 8 channels set-up for semg, etc. 37

38 Unit Name This dialogue allows the name assigned to the selected DataLINK unit in the Connected DataLINK Units Window to be changed. Note that this name is stored inside the DataLINK unit itself. Y axis & Time Marker Mode If ticked, dragging the mouse sets a marked time area. One region may be marked in time and one region may be marked in Y values. These areas are used to calculate results and to perform actions such as delete and zoom. Marking an area involves selecting either Mark Time Axis or Mark Y-Axis from the toolbar or set-up menu and dragging the mouse within the display window. Press and hold the left mouse button at the start of the desired area and drag the mouse to the desired area end; releasing the mouse sets that area. An existing area may be adjusted by pressing the right mouse button and dragging with the cursor near to either end of an area. A very narrow time marker may be added by holding the shift key when pressing the left mouse button. This is useful when values need to be read from the trace. If the marker is near to an event marker, then the marker will "snap" to that marker. The snap region is related to the time axis so zooming in will allow the marker to be set very close but not actually on an event marker if required. Marked areas can be removed using two techniques: The current markers may be removed by simply clicking with the left mouse button without dragging. Note that this only removes the time markers if in Mark Time Axis mode or the Y markers if in Mark Y-Axis mode. Press the Clear Both Markers toolbar button to remove all markers. Values relating to a marked area are displayed in the Results window. The values displayed often require a trace tab to be selected first. The Time Span is the width of the marked area. The start and end times are displayed along with the trace values at those times. If a Y-axis marker is set, the top and bottom marker values are shown along with the difference between these values. If a time axis marker is set, the results apply to the marked time only. A convenient way to display a time region of interest is to mark the area first and then press the Zoom To Time Markers button on the toolbar. 38

39 Y Axis Marker Mode If ticked, dragging the mouse sets a marked Y value area. Clear Markers Clear both the time and Y value markers. Time Marker Snap Selects between no snap grid or a fine and course snap grid when setting the time markers. A grid simplifies the setting of time markers to a particular time. FFT High Pass Filters Allows DC (Remove DC Filter) and/or low frequencies (Remove Low Frequencies Filter) to be rejected from Power spectrum and mean/median frequency calculations. Colours Change the colour of the graph background and gridlines. Also allows all colours to be reset to default colours. Graph Line Width Determines the width of the trace lines. "Thin" and "x1" are the same on the screen but "thin" produces a very thin line when copying the graph to the clipboard. Port Use this option to select the USB port, or COM port on older units. Factory Calibration (Accessed only by manufacturer.) View Menu The View Menu offers the following commands: Traces during Record Enables the user to view or hide all traces being displayed during a recording. Recording Information This dialogue displays information about the current recording held in memory. If a channel is shown in gray then no recording was made on that channel. The units box and the boxes for zero and full scale are not relevant for Biometrics goniometers. The number of samples per channel is related to the sampling rate and the duration of the recording. If this dialogue is displaying information about a recording that has been loaded from disk, the channel titles may be changed. 39

40 Main Toolbar Use this command to display and hide the Main Toolbar, which includes buttons for some of the most common commands. A check mark appears next to the menu item when the Toolbar is displayed. The toolbar may be moved to any of the four sides of the main window or left floating in the middle by dragging the vertical bar to the left of the toolbar. Analysis Toolbar Shows or hides the analysis toolbar. A check mark appears next to the menu item when the Toolbar is displayed. Graph Key The Graph Key window controls the traces that are to be displayed and the units to use on the Y-axis. The contents of this window reflect the state of the current active display window. The current active window has a horizontal red line drawn along its top. If the data has been loaded from disk or it has been saved to disk, the file name used is displayed at the top left. If a trace or channel is present in the data then the trace check box is enabled and its title displayed. A disabled checkbox means that the trace was not recorded. Analogue traces are numbered 1 to 8 and digital traces, a to d. The Y-axis values are in engineering units as determined by the Units selection and the set-up of that channel when the recording was made. The selected units are displayed just above the trace colour boxes. The Clear All button is useful for deselecting all traces before selecting one or two for display. Changes made in the Graph Key window will cause an automatic redraw of displays where necessary. Trace Line Appearance To change the colour of a trace line, click on the black box containing the trace line to be change. The resultant dialogue allows the line colour to be changed for both screen display and when copied to the clipboard. If the graph must be printed, take care not to choose a colour that is the same as the paper. The default white background colour scheme is useful for this. Select Graph Line Width from the Set-up menu to change the thickness of all graph lines. Note that lines thicker than one may obscure detail in favour of a more prominent line. "Thin" and "x1" are the same on the screen but "thin" produces a very thin line when copying the graph to the clipboard. Use the Colours item on the Set-up menu to change: o The graph background colour. o The graph gridlines colour. o Reset colours to a default black or a default white background colour scheme. 40

41 Digital Traces Digital traces may be displayed in one of two formats. As separate traces that indicate logic 0 or logic 1. As trace pairs where two digital inputs are combined to produce a number in the range 0 to 3. In this mode, the weighting of the digital inputs may be changed; selecting 1/2 for example, results in trace "a" contributing 0 or 1 to the final display and trace "b" contributing 0 or 2. Results Show: Markers Calculations Repetitions Excursions The Results window displays information about the traces within the current active display window whether or not they are currently visible. Most of the values relate to a particular analogue trace 1 to 8 as selected by the active tab. If the data has been loaded from disk or it has been saved to disk, the file name used is displayed at the top left. The range of time displayed in the active window (Window Span) is shown below the filename. The time values used throughout are to a resolution of 0.01 seconds. The times are in the HH:MM:SS.HH (Hours:Minutes:Seconds.Hundreths) format although the hours and minutes may be omitted if they are zero. The title of the selected trace and its engineering units are displayed below the selection tabs. If a time axis marker is set, the results apply to the marked time only. The message "Complete Trace" or "Marked Area" is displayed to indicate the area used to calculate results. Results are calculated dynamically - it is not necessary to request a calculation, as the displayed values are always current. Markers If a marked time is set then values relating to that marked time are displayed. The values displayed often require a trace tab to be selected first. The Time Span is the width of the marked area. The start and end times are displayed (HH:MM:SS.HH to HH:MM:SS.HH) along with the trace values at those times just below. If a Y axis marker is set: The top and bottom marker values are shown along with the difference between these values. The values are displayed using the engineering units of the selected trace. 41

42 Calculations If a marked time is set then values relating to that marked time are displayed. The Max/Min values are the maximum and minimum values of that trace over the complete trace or marked area. The Mean value is the average trace value over the complete trace or marked area. The values are displayed using the engineering units of the selected trace. Repetitions If a marked time is set then values within that marked time are displayed. The number of Repetitions indicates the number of repeated cycles within a trace. In order to count as a repetition, the trace must change direction twice in succession. In order to overcome the effects of noise, the change necessary to be taken as a change of direction can be set as the Repetition Threshold value within the Settings window. The trace must reverse direction for more than this percentage of full scale to be seen as a change of direction. Excursions If the Y markers are set then the number of excursions is displayed. An Excursion is when the trace moves over or under the marked Y values. In order to overcome the effects of noise, it is possible to set the minimum time allowed for an excursion - any movement of the trace over/under for less than the minimum time is ignored. The Minimum Excursion Time value is set within the Settings window. The percent values in brackets show the amount of time spent over and under the marked Y values. Settings Show: Filters Overview Rectify Filter Average Filter RMS Filter Velocity Filter Integrate Filter Offset Filter Add Filter Add for Zero Filter Scale Filter Median Frequency Mean Frequency Determining the area under a curve Filters Memory 42

43 The Settings window displays the settings used for the traces within the current active display window. The values relate to the analogue traces 1 to 8. Changes made in the Settings window will cause an automatic re-calculation of results and redrawing of displays where necessary. The Minimum Excursion Time value relates to the Excursion number calculation in the Results window. In order to overcome the effects of noise, it is possible to set the minimum time allowed for an excursion - any movement of the trace over/under for less than the minimum time is ignored. The Minimum Excursion Time cannot be more than 1 second. The Repetition Threshold value relates to the Repetitions calculation in the Results window. In order to overcome the effects of noise, the change necessary to be taken as a change of direction can be set. The trace must reverse direction for more than this percentage of full scale to be seen as a change of direction. The Repetition Threshold must be less than 100%. Any invalid value will result in a beep sound and no other action. Filters Overview Every trace in every window may have up to four filter effects applied. The original data is subjected to the first enabled filter. The output from this filter is subjected to the next enabled filter and so on up to a maximum of four filters. The output from the final filter is displayed. Adding filters does not change the stored waveform in any way; it is purely a display filter. The Clear button is a quick way to clear all of the filters for the active trace. Each of the four filters has the following options: A filter enable checkbox. A filter is ignored unless the left-hand box contains a check mark. A filter type selection. If this is blank or if the enable checkbox is empty, no filter will be applied. A filter constant number. The operation of this number depends upon the filter type selected but it is intended to control the operation of the chosen filter. The meaning of this number may be changed by the Samples / ms selection at the bottom right of the Settings Window if relevant. The units for this constant are displayed to the right of the value scroll arrows. The recommended way to change the filter constant number is to use the up/down arrows next to the number as these have suitable limits and increments programmed. Any filter producing a frequency output or any frequency analysis Window makes use of a Windowing function as specified by the selection at the bottom left of the Settings Window. 43

44 Using FFT Windowing Functions When data is captured, a 'window' is effectively opened on the signal to view the waveform for a period before the 'window' is closed again. Before and after the window is open, the FFT calculation has no idea about the value of the signal. For example, the four waveforms shown below contain the same captured data (shown in grey) but have different frequency contents. Ti me Ti me Ti me Ti me An FFT assumes that the data sequence is part of a signal that repeats periodically as illustrated by the saw tooth waveform on the lower right of the above diagram. The consequence of assuming a periodic continuation of the underlying signal is that if the amplitude at the start and the end of the sample of data are not equal then the signal will be analysed to contain a discontinuity, whether the signal has such a discontinuity or not. Since sharp discontinuities have broad frequency spectra, these will cause the signal's frequency spectrum to be spread out. The spreading means that signal energy that should be concentrated only at one frequency, instead, leaks into all the other frequencies. This spreading of energy is called 'spectral leakage'. Since spectral leakage is related to discontinuities at the ends of the measurement time, it will be worse for signals that happen to fall such that there are large discontinuities. This is a problem since the FFT will only be an accurate calculation of the frequency content if the captured data is one or more complete cycles of a periodic underlying signal. This is normally not the case. In order to improve the accuracy of the FFT, it is normal practice to multiply the sampled data by a window function before implementing the FFT. This window function is a series of numbers that are usually symmetrical with the mid-point of the sample time range and have a mid-point value of one. For example, the Triangle or Bartlett window: 44

45 Original Signal Time Window Function Time Original Signal X Window Function Time A number of window functions are possible including a Rectangular Window that does not actually change the data at all. Some of the window functions provided are: Rectangle Triangle Blackman std Blackman opt Hamming Hann n 45

46 Rectangle window Time Triangle or Bartlett window Time Hann window Time Hamming window Time Blackman window Time In order to compare the different windows, they may be plotted on the same axis as follows: Note that the Triangle window is also called the Bartlett window. The choice of window function is usually made after some experience processing the type of signals being used. However, some guidelines can be given: Use a rectangular window for transient signals; Hann (von Hann) and Hamming for continuous waveform data; Rectangular (Flattop) for accurate amplitude measurements or Blackman for maximum frequency resolution. See the section FFT Accuracy for information relating to the integrity of the results. 46

47 Rectify Filter This filter simply converts a negative value to a positive value of the same magnitude. No filter constant is required. Average Filter A moving average filter may be applied to any waveform. When enabled, each point calculated in a trace is the average of a number of values up to and including the current point. The number of values is the filter constant and may be set from 2 samples upwards. The filter constant may be specified in samples or milliseconds where the number of milliseconds is the number of samples multiplied by (1000/sampling rate). The moving average generates as many outputs as inputs. For example, assuming a filter constant of 3, the following calculations are performed: Output 1 = Input 1 Output 2 = Average of inputs 1 and 2 Output 3 = Average of inputs 1, 2 and 3 Output 4 = Average of inputs 2, 3 and 4 Output 5 = Average of inputs 3, 4 and 5 Output n = Average of inputs n-2, n-1 and n RMS Filter HINT: The average filter is useful for reducing high frequency noise in a waveform. For example, if a heart beat trace that is sampled at 1000Hz contains 50Hz mains interference, it may be reduced by averaging over one mains cycle (1/50th second). One mains cycle corresponds to 20 samples (1000Hz sample-rate divided by 50Hz interference) so averaging 20 values will reduce the noise significantly. Note that averaging over 40, 60, 80, samples will also reduce the noise but it may also reduce the signal of interest. Each sample of data is first squared and then a moving average is taken of these squares. The output is the square root of each average calculated. The filter constant may be specified in samples or milliseconds where the number of milliseconds is the number of samples multiplied by (1000/sampling rate). See the Average Filter for information on the averaging process. 47

48 Velocity Filter The velocity filter involves calculating the rate of change of data at every data point. This is effectively the gradient of the tangent to the line at that point. To obtain a suitable gradient, a least-squares method is used to estimate a straight line using the data either side of the data point being calculated. The gradient of this line is the filter output. The filter constant defines the number of data points used in the least squares line estimation. It may be specified in samples or milliseconds where the number of milliseconds is the number of samples multiplied by (1000/sampling rate). Using this filter will alter the displayed units. For example, if the original units are degrees then the filtered units will be degrees/sec. Integrate Filter The integrate filter calculates the area under the graph from the start up to the point being displayed. This filter often produces a rapidly rising/falling graph when the data is not centred on zero. The filter constant defines a divider used to reduce the calculated area for each point. This is useful when the data would otherwise produce an integrate output that is too large to display. Using this filter will alter the displayed units. For example, if the original units are degrees then the filtered units will be degrees-sec. Offset Filter The offset filter simply adds or subtracts a percentage of full scale from every data point. This has the effect of moving the trace up or down in the window. The filter constant defines percentage of full scale and may be positive or negative. Add Filter The Add filter simply adds or subtracts a percentage of full scale from every data point. This has the effect of moving the trace up or down in the window without changing the y-scale. The filter constant defines percentage of full scale and may be positive or negative. The filter constant can be set to 2-decimal places. The Spin control to the right of the filter constant changes the value by 10% or 1% with the shift key held or 0.1% with the Ctrl key held. 48

49 Add for Zero Filter This filter operates in the same way as the Add Filter but in an automatic way. The result is to add or subtract a percentage of full scale from every data point to make the average value of the waveform zero in engineering units. The filter constant used to do this is displayed but cannot be changed. The Add for Zero Filter is useful for correcting DC offsets in transducers. If for example, an EMG probe produces 0.5mV DC with no input then applying this filter corrects the waveform to be centred around 0mV. Scale Filter The scale filter simply multiplies every data point by a percentage of full scale. This has the effect of increasing or decreasing the size of a trace in the window. The filter constant defines percentage of the original value. Constants less than 100% will reduce the amplitude of the trace whilst constants more than 100% will increase the amplitude of the trace. Median Frequency Filter The median frequency is calculated for a block of samples whose length is defined by the filter constant. This calculation is repeated as necessary across the trace and the resulting frequencies plotted as a series of lines connecting the calculated median frequencies. The following steps are performed: A block of samples defined by the filter constant is taken and zero padded to the nearest power of 2. A Windowing function applied to the data as specified by the selection at the bottom left of the Settings Window. See Using FFT Windowing Functions for more information. An FFT is performed and, if selected, FFT High Pass Filters are used to Remove DC and to Remove Very Low Frequencies from the calculations. Note that a large DC component can seriously degrade the accuracy of the median frequency calculation. The amplitude magnitude of each FFT output frequency is squared. The median frequency is determined such that the area of the amplitudesquared frequency graph below the median frequency is the same as above the median frequency i.e. there is equal power either side of the median frequency. The process is repeated for the next block of samples. 49

50 Set-up FFT High Pass Filter Command - Remove DC When a check mark is against this menu item, the average value of the waveform is subtracted from the waveform before any operation involving an FFT or Power Spectrum graph. For most waveforms, this will remove most of any DC offset that can distort the calculation of Mean Frequency or Median Frequency. Removing the DC offset will also improve the resolution of the Power Spectrum graph. This filter is in addition to the Set-up FFT High Pass Filter Command - Remove Low Frequencies filter. For most situations, the Remove DC filter should be on and the Remove Low Frequencies filter should be off. Set-up FFT High Pass Filter Command When a check mark is against this menu item, the lowest 2% of the frequency range is excluded from any operation involving an FFT or Power Spectrum graph. This filter is in addition to the Set-up FFT High Pass Filter Command - Remove DC filter. For most situations, the Remove DC filter should be on and the Remove Low Frequencies filter should be off. For example, if a trace is sampled 1000 times per second, any frequency analysis will produce results for the range zero to 500Hz. Often, however, the waveform includes a DC component that can distort the calculation of Mean Frequency or Median Frequency. Using the high pass filter results in all frequencies below 10Hz (2% of 500Hz) being rejected - which of course will also reject the DC component. FFT Accuracy The FFT algorithm assumes that the number of samples can be expressed as a power of 2. In reality, this means that the number of samples should be 64, 128, 256, 1024, 2048, 4096, Fewer than 256 samples would probably not give enough detail and more than 4096 leads to long computation times. In real-life, it cannot always be guaranteed that the number of samples to be analysed is an exact power of 2. The normal solution to this is to: Change the number of samples being analysed to an exact power of 2 or in practice, a power of 2 or just below. Pad the data by adding a sequence of zeros until the number of samples is the next nearest exact power of 2. 50

51 The first option can often be satisfied by selecting a filter length of 64, 128, 256, 1024 or 2048 when calculating median or mean frequencies. The second option is automatically used when the filter length is not an exact power of 2 or when the length of a frequency analysis is not an exact power of 2 as is often the case. This zero padding will create a distortion in the frequency analysis that can be minimized by ensuring that the number of samples is just below an exact power of 2 rather than just above. Displaying a frequency analysis graph using a signal length of 2040 samples will be much more accurate than one containing 2050 samples. Note that the minimum number of samples used by any FFT operation such as a Power Spectrum Graph, Mean Frequency or Median Frequency display is 64. Setting less than 64 samples will still result in 64 being used. FFT High Pass Filters may be used to Remove DC and Remove Very Low Frequencies from the calculations. Note that a large DC component can seriously degrade the accuracy of the Mean Frequency or Median Frequency display as well as reducing the resolution of the Power Spectrum Graph. For most situations, the Remove DC filter should be on and the Remove Low Frequencies filter should be off. Mean Frequency Filter The mean frequency is calculated for a block of samples whose length is defined by the filter constant. This calculation is repeated as necessary across the trace and the resulting frequencies plotted as a series of lines connecting the calculated mean frequencies. The following steps are performed: A block of samples defined by the filter constant is taken and zero padded to the nearest power of 2. A Windowing function applied to the data as specified by the selection at the bottom left of the Settings Window. See Using FFT Windowing Functions for more information. An FFT is performed and, if selected, FFT High Pass Filters are used to Remove DC and to Remove Very Low Frequencies from the calculations. Note that a large DC component can seriously degrade the accuracy of the mean frequency calculation. An FFT is performed and all frequencies below (maximum frequency / 50)Hz are rejected; this corresponds to 10Hz at 1000 samples / second. The amplitude magnitude of each FFT output frequency is squared. The mean frequency of the resultant amplitude-squared against frequency graph is determined. The process is repeated for the next block of samples. See the section FFT Accuracy for information relating to the integrity of the results. Determining the area under a curve A common requirement is to measure the area under a curve over a section of the waveform; this area is between the zero line and the curve. This is an integrate operation over a marked area as follows: 51

52 For convenience, create a copy of the waveform display below the original using New Graph from the Window menu or preferably, by splitting the existing display (see Creating More Displays into the Data). In the copy window, turn on the desired trace and choose the integrate filter. Within the original window, mark the area that needs measurement. Select the copy window by clicking on the vertical axis to avoid disturbing the marked area. The Results Window for the integrated waveform shows the accumulated area value at the left and right markers but it is the Value Difference number that gives the area under the curve for the marked area alone. The units will be shown in the Results Window if units have been assigned for the original waveform. For example, original mv values produce mv-s area values. For waveforms such as EMG signals that go above and below zero, it may be necessary to Rectify the copy waveform before applying the integrate filter. Note that it may be necessary to use the Add Filter or Add for Zero Filter to correct for a DC offset in the EMG transducer. If for example, an EMG probe produces 0.5mV DC with no input then applying this filter corrects the waveform to be centred around 0mV. If the EMG signal is not accurately centred around 0mV then the results of the EMG signal integration will normally be masked by the DC offset integration. Filters Memory When a number of filters for a channel have been set-up for a particular application, they may be saved to a single filter-set memory and recalled from that memory. Press the shift key and the RM button to save the state of all four filters to memory. Press the RM button alone to recall the state of all four filters from memory. Connected Units Inputs The Input Values window displays the current analogue and digital inputs in engineering units. The box will be empty if there is no remote communications. If a high alarm is detected, the background colour changes to red. If a low alarm is detected, the background colour changes to blue. Alarm colour changes stay for at least 0.3 seconds. Consequently, a high and low alarm may be indicated simultaneously as a combination of the two alarm colours. 52

53 Status Bar Use this command to display and hide the Status Bar. The Status Bar describes the action to be executed by the selected menu item or depressed toolbar button, and keyboard Latch State. A check mark appears next to the menu item when the Status Bar is displayed. Graph Grid Lines Shows or hides the grid lines used on all graphs. Exchange X and Y For a trace/trace graph only, exchange X and Y-axis. Log Power Spectrum Toggle between Log and Linear Y-axis on all Power Frequency Spectrum graphs. Due to the limitations of the FFT operation and the consequence of Windowing Functions and any necessary zero padding before the FFT, it is not possible to display accurate amplitude units. The units displayed are therefore only relative units within the graph and cannot be used to compare between different waveforms. Zoom Menu The Zoom menu offers the following commands in addition the ones available on the analysis toolbar: All Show the complete waveform in the current window. Auto Y Change the Y-axis to show the full signal range within the window time. To Time Markers Show the complete marked time in the window. Around Centre Toggle between zoom around the middle of the graph, or zoom whilst maintaining the left/bottom of the graph. Transfer Menu Start Allows you to open a new window and start collecting data. 53

54 Timed Transfer Opens a new window to set data collection for a set time. The system will automatically stop data transfer when the selected time interval has passed. Time is set in hours:minutes:seconds Window Menu The Window Menu offers the following commands: Split Window A window is, or can be, split into two or more scrollable panes. A splitter control (or "split box") in the window frame next to the scroll bars allows the user to adjust the relative sizes of the panes. Each pane is a view on the same data file but may contain different traces within that file. This command changes the cursor within the current window to allow the window to be split into 1, 2 or 4 panes. New Graph Use this command to open a new window into the same data as the active window. You can open multiple page windows to display different parts or views of a recording at the same time. Note that the Track Time Axis Command and the Track Time Axis All Windows Command must not be set to view different time windows within a recording. When you open a new window, it becomes the active window and is displayed on top of all other open windows. In order to indicate the current active window when there is more than one window displaying graphs, a horizontal red line is drawn along its top. Track Time Axis When ticked, any changes to the time axis will be repeated in all others windows showing the same recording. Track Time Axis All Windows When ticked, any changes to the time axis will be repeated in all others windows showing any recording. 54

55 New Power Spectrum Graph Use this command to open a new window into the same data as the active window; this window will show a frequency analysis of the data. To display a frequency analysis for part of a waveform, select the time of interest before selecting this command. The maximum frequency on the x-axis is determined by the maximum sampling rate of the traces selected for display. For example, if a file contains three traces at 1000Hz sampling and one at 100Hz sampling then displaying the frequency analysis for all four traces would use an x-axis range of zero to 500Hz. Displaying just the lowest sampling rate trace would use an x-axis range of zero to 50Hz. The Toggle Log Power Spectrum Command in the View menu allows the Y- axis to be toggled between linear and logarithmic amplitude. A Log scale lifts up the smaller amplitude parts of the display. The frequency analysis makes use of a Windowing function as specified by the selection at the bottom left of the Settings Window. See Using FFT Windowing Functions for more information. Due to the limitations of the FFT operation and the consequence of Windowing Functions and any necessary zero padding before the FFT, it is not possible to display accurate amplitude units. The units displayed are therefore only relative units within the graph and cannot be used to compare between different waveforms. High Pass Filters may be used to Remove DC and to Remove Very Low Frequencies from the calculations. Note that a large DC component can seriously reduce the resolution of the Power Spectrum graph. For most situations, the Remove DC filter should be on and the Remove Low Frequencies filter should be off. See the section FFT Accuracy for information relating to the integrity of the results especially when a small section of waveform is analysed. You can open multiple Power Spectrum windows to display different parts of a recording at the same time. Note that the Track Time Axis between Windows Command and the Track Time Axis All Windows Command must not be set to view different time windows within a recording. When you open a new Power Spectrum window, it becomes the active window and is displayed on top of all other open windows. In order to indicate the current active window when there is more than one window displaying graphs, a horizontal red line is drawn along its top. See the section, Creating More Displays into the Data for more information. New Trace / Trace Graph When exactly two analogue traces are selected in the Graph Key window, this will open a new window plotting one trace against the other. Use the Exchange X and Y View menu item to reverse the contents of the X and Y- axis. When a trace/trace plot is the active window, zooming and scrolling operate as normal but markers cannot be set. 55

56 The traces used for the X-axis and Y-axis are indicated in the Graph Key window. The Exchange X and Y toolbar button reverses the position of the two traces. The trace colour is that set for the X-axis trace. The trace/trace graph and key may be copied to the clipboard as with a normal waveform. Cascade Use this command to arrange multiple opened windows in an overlapped fashion. Tile commands Use these commands to arrange multiple opened windows horizontally or vertically in a non-overlapped fashion. Arrange Icons Use this command to arrange the icons for minimized windows at the bottom of the main window. If there is an open page window at the bottom of the main window, then some or all of the icons may not be visible because they will be underneath this page window. The Help menu offers the following commands, which provide you assistance with the application: Help Menu The Help menu offers the following commands in addition to the ones available on the analysis toolbar: Help Topics Displays an index to topics on which help is available. About Displays the version number of the application. 56

57 EXAMPLE OF CALCULATING WORK DONE DURING EMG ACTIVITY. BACKGROUND A DataLINK system was set up whereby right forearm extensor EMG was collected on channel 5 and right hand grip strength was collected on channel 6. With the DataLINK connected to the host PC via the USB port, with the Biometrics DataLINK application running, the channels were programmed for the respective sensors using the default settings within the analogue set up dialogue box. Approximately 50 seconds of data was collected where the right handed male subject was asked to grip to a maximum 10 times for approximately 2 seconds. After data collection a graph of the data automatically displayed showing both traces of data on the one graph. METHOD 1. Split the existing graph into 2 equal horizontal windows by using the Split Window command within the Windows menu. (hint: make certain that the cursor is off to the right of the graph and approximately central in the vertical plain before the left mouse button is pressed, otherwise the graph may be split into 4 windows not the required 2. Alternatively, this may be completed by dragging down on the standard windows split window bar located towards the top right of the window). 2. Activate the new window by clicking anywhere within it with the left mouse button. Proof of activation will be the red line along the top of the graph. 3. From within the view menu activate the graph key and display the EMG trace within the new window. 4. From within the View menu activate the Settings menu and then apply the Add for Zero, Rectify and Integrate filters respectively to the trace as shown. The Add For Zero Filter is applied to remove any DC offset which could mask the EMG integration. 57

58 5. Using the mouse place the cursor at the beginning of the burst of grip muscle activity and press the left mouse button. Still holding the left mouse button move the cursor to the end of the first grip muscle activity burst and release the mouse button. The time period of the muscle activity is 2.00 S. 6. The amount of work done is displayed as the value difference. In the above example the work done is mv/s. 7. To calculate the work done during the other muscle activity bursts move the markers using the mouse as described above. 8. The above filters to calculate work done may be saved to memory for easy recall by pressing the shift key and the RM button. They are then recalled at a later date by pressing the RM (recall) button. 58

59 TECHNICAL INFORMATION DataLINK Application Interface Functions Show: Microsoft Visual Basic 2005 Interface Example Microsoft Visual Basic 6 Interface Example Microsoft Visual C Interface Example for Windows Microsoft Visual C++ 6 Interface Example for Windows The functions that allow other applications to interface to the DataLINK configuration application are contained in the file OnLineInterface.dll. This DLL is registered with Windows during installation and afterwards allows direct data and control access to the DataLINK Application. Two interface functions are provided - the first provides data and control status information with start/stop control and the second gets the next block of data from a channel buffer. Both of these functions are provided with on-line help and a number of supporting constants. Note that these functions are members of the OnLine Class and an object of that class must be defined before using the functions. OnLineStatus Function C++ Prototype: VB Prototype: int stdcall OnLineStatus(long channel, long statustype, long *pstatus); Sub OnLineStatus(channel As Long, statustype As Long, pstatus As Long); This function provides data and control status information with start/stop control. The statustype parameter must be one of the StatusType command constants listed below. Note that any command will return ONLINE_COMMSFAIL in pstatus if communications with the hardware fails. StatusType Constant Value Comment ONLINE_GETERROR 0 channel is unused. Return with the current status in pstatus. ONLINE_GETENABLE 1 pstatus returns with 1 if the specified channel is enabled or 0 if it is not. ONLINE_GETRATE 2 pstatus returns with the number of samples per second on the specified channel. ONLINE_GETSAMPLES 3 pstatus returns with the number of unread samples on the specified channel or ONLINE_OVERRUN. ONLINE_GETVALUE 4 pstatus returns with the (current value ) on the specified channel. ONLINE_START 5 channel is unused. Start or re-start the data transfer. ONLINE_STOP 6 channel is unused. Stop the data transfer. Error Return Constants Value Comment ONLINE_OK 0 No communications or buffer errors. ONLINE_COMMSFAIL -3 Communications with the hardware has failed. ONLINE_OVERRUN -4 The internal buffer has overflowed and some data has been lost. OnLineGetData Function C++ Prototype: VB Prototype: int stdcall OnLineGetData(long channel, long sizemstoread, SAFEARRAY ** DataArray, long *pactualsamples); Sub OnLineGetData(channel As Long, sizemstoread As Long, DataArray() As Integer, pactualsamples As Long); 59

60 This function return the next block of data received on the specified channel. The number of samples returned in the DataArray array will be no more than (sizemstoread * sample rate) where sizemstoread is a number of milliseconds. If insufficient samples are available then all that is available will be returned. If no error occurred, pactualsamples will return with the actual number of samples returned in the DataArray array. If an error did occur, pactualsamples will return with a negative value. Visual Basic 2005 Interface Example To use these functions within Microsoft Visual Basic, the interface reference must be enabled for the current project (select Add References from the Project menu). Once the "Biometrics DataLINK Interface Library" is enabled, use the Object Browser with OnLineInterfaceLib selected to see the available functions and constants along with on-line help about the functions. This example project is supplied within a zip file on the Biometrics Installation disk. Layout the following form and add two labels named StatusText and ChannelText. Also, add a button named StartStopButton and a 1000mS interval timer called Timer1. Public Class Form1 ' DataLINK and the DataLINK PC application must be installed and working and not running in file save mode. ' Declare an interface object to provide a link to the data Private DataLINK As OnLineInterfaceLib.OnLine Dim started As Boolean Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick ' Here every second Dim status As Integer ' Declare variables to use in data transfer Dim samples As Integer Dim channel As Integer Dim data() As System.Int16 Dim y As Integer Dim Point As Integer ' Get some status information and display it 60