Instrument Control and Data Acquisition with Chromeleon

Transcription

1 Technical Note 67 Instrument Control and Data Acquisition with Chromeleon Introduction Laboratories generally have a combination of chromatography devices from different manufacturers and, therefore, face several challenges in managing instrument control and data acquisition. These challenges generally center on the inherent difficulties of using several different chromatography applications to control different instruments including higher training and validation costs. The Chromeleon Chromatography Management System (CMS) offers a solution to these laboratories. Chromeleon provides control of more than 250 instruments from over 25 different manufacturers, is easy to learn and use, and allows instrument methods to be easily transferred from one instrument to another, even between those from different manufacturers. This document describes the problems encountered with the traditional laboratory environment, the challenges that Dionex overcame in order to provide control of all these instruments, an overview of how instruments are controlled with Chromeleon, and a summary of the benefits Chromeleon offers. Traditional Environment The majority of chromatographic instrument manufacturers provide a chromatography software application that controls their own instruments and processes the acquired data. Traditionally, laboratories have used the software application provided by the hardware manufacturer to control these instruments. This can be a good strategy to adopt if all chromatographic instruments used come from the same manufacturer, but as soon as a system is required that this manufacturer cannot provide it becomes necessary to use a different software application. There are several disadvantages to using different software applications: Lack of compatibility it is often very difficult (and sometimes impossible) to transfer data from one chromatographic software application to another. This makes it more difficult to transfer methods from one instrument to another, or even to compare data generated on one instrument against data generated on another. Higher maintenance costs each software package must be administered separately (e.g., different backup mechanisms, different operating procedures, etc.). Higher training costs users have to be trained on several different software packages. Higher validation costs each different software package must be validated. Complex operation in a mixed system simple operations become complex. For example, to see the status of all instruments in the laboratory it is necessary to open several different applications, record the status of each instrument controlled by that application, and then collate this information for all applications. Technical Note 67

2 Open Environment All the problems associated with the traditional environment are solved by adopting an open environment that allows instruments from different manufacturers to be controlled by a single application. One of the main advantages of Chromeleon is that this concept of an open Chromatography Management System (CMS) was a core design feature from the beginning. The limitations of the traditional environment were recognized and the software designed to eliminate those limitations. Chromeleon can control more than 250 instruments from over 25 different manufacturers. The main mechanisms for instrument control are detailed in the following section. Chromeleon Architecture For normal operation, there are three components in Chromeleon that must communicate: Chromeleon Datasource, Chromeleon Server, and Chromeleon Client. Any combination of local and network access is supported by Chromeleon s three components. All three can be on the same computer, or all three can be on three different computers, or any combination in between. It is also possible for the Chromeleon Client to communicate with multiple servers and datasources, and for multiple servers to use a single datasource. Generally, any Chromeleon components on the same computer will communicate automatically without the need for much configuration. When components are installed on different computers they need to be configured to allow communication. A peer-to-peer or client/server network is required for this, typically in the form of an existing Office LAN (usually a domain). Alternatively, a direct crossover cable connection can be used between two computers (workgroup). Chromeleon Datasource The Chromeleon Datasource is a structured file system indexed by a database. It is used by Chromeleon for all data and file storage. Note that Chromeleon does not need to be installed on the computer that contains a datasource. Chromeleon Server The Chromeleon Server is a background application that monitors and controls an instrument. It executes programs, sequences, and batches that are stored on a datasource, and saves data from an instrument as a channel into the same datasource. The Chromeleon Server is the only component that communicates with an instrument. Therefore, to control it, the computer running the Chromeleon Server needs to be physically connected to the instrument, either through a LAN, USB, or other connection protocol. The other two components can be remote from the server if a network is available to connect them. Chromeleon Client The Chromeleon Client is the User Interface part of the Chromeleon software. It uses a browser interface to interact with the Chromeleon Datasource, and a Control Panel or Panel Tabset to interface with the Chromeleon Server. Figure 1. Chromeleon Client showing the browser connected to a datasource called CM_Data. Challenges Raised by the Open Environment Although this open environment removes the limitations associated with the traditional environment, it raises additional challenges: How is it possible to have a common interface for different instruments? How is it possible to ensure the quality of instrument control provided? This section first details the basic architecture of the open Chromeleon environment and then how additional challenges are overcome by Chromeleon. 2 Instrument Control and Data Acquisition with Chromeleon

3 Common Interface for Instruments In order to provide a common interface for different instruments from different manufacturers, the concept of a Chromatography Basic Input/Output System (C-BIOS) was developed. This concept operates as follows: Uniform Control Commands A uniform set of control commands was developed to meet three main criteria: Easy to learn Easy to use Easy transfer of control commands between instruments The basic format of the control commands is: [module].[command] = [parameter]. Table 1 shows some examples of control commands. Table 1. Examples of Control Commands Module Setting Control Commands Set pump flow to 1.0 ml/min Pump.Flow = 1 Perform sample injection Sampler.Inject Set Column oven temperature to ColumnOven.Temperature = C Set wavelength of detector channel UV_VIS_1.Wavelength = 254 1(UV_VIS_1) to 254 nm These control commands are fully instrument independent. For example, the control command for pump flow will work on practically every pump supported by Chromeleon. As such, these control commands meet all the development criteria: Easy to Learn These control commands are intuitive and can be quickly learned once the basic structure is understood. Easy to Use As all control commands are the same, independent of instrument manufacturer, they are easy to use. Operators do not need to learn different commands for different instruments. Easy transfer of control commands between instruments As the control commands are the same for different instruments, method transfer is effortless. For example, the pump.flow command will work equally well on a Dionex Summi t HPLC and an Agilent 1100 HPLC. Communicating Control Commands to Instruments Once the user has defined the controls they are sent to the Instrument Control Interface via Remote Procedure Calls (RPC) to the Chromeleon Server. This translates the command in to the native control codes for the instrument. Execution of Commands The instrument executes the command as soon as it receives it. Any errors generated by the execution of the command (such as a high pressure limit being exceeded due to an increased flow rate) are then sent back to the user. Quality of Instrument Control Dionex takes special care to ensure that all drivers developed for instruments are fully tested and validated before release. Rigorous procedures ensure that all drivers made available are of the highest quality. The basic process is: 1. The testing starts at the control command level. Every control command, no matter how minor, is tested by a team of test engineers. For some instruments there may be literally hundreds of available commands. The basic test process for each command is to enter three valid values, a limit(s) value, values that exceed the limit(s), and invalid values. For example, a pump may allow flow values between 0 and 10 ml/min. The test and validation procedure checks that: Values of, for example, 1, 4, and 8 ml/min are executed correctly. Values of, for example, 0 and 10 ml/min are executed correctly. Values of, for example, 1 and 11 ml/min are not executed and that an appropriate warning is displayed. Values of, for example, a or & are not accepted and that an appropriate warning is displayed. 2. Next, the help text for each command is checked for accuracy and usefulness. 3. Following this, the error handling is thoroughly checked by forcing typical errors and checking the response. For example, check that when the pump pressure exceeds its limit the flow rate is reduced to 0 ml/min and an appropriate error message is provided. 4. The drivers are then tested under typical day-to-day operations where multiple commands are executed as part of a method. For example, a pump gradient profile may be created and a check performed to show that the gradient was generated correctly. Technical Note 67

4 5. The driver is also tested to ensure that inappropriate use is prevented. For example, tests are made to show that if data acquisition is being performed by a UV detector it should not be possible to turn off the lamp. 6. Finally, to ensure robust and reliable operation the instrument is run for a minimum of 24 h to check that no errors occur, that computer performance is not affected, and that no memory leaks occur. Additional tests are created that are based on instrument specific tests requirements. Each instrument has its own test plan and test results, and these can be reviewed at any time as part of a vendor audit. These plans ensure that all instrument drivers developed by Dionex are of the highest quality and validated for laboratory use. Once a driver is released, a dedicated tracking system ensures that any reported errors (e.g., errors caused by an unusual series of commands) are investigated and corrected. Errors found in drivers for third party instruments are treated as seriously as errors found in the drivers for Dionex instrumentation. Instrument Control with Chromeleon The Chromeleon CMS provides control for a vast number of different chromatographic instruments and has all of the advantages associated with the traditional laboratory environment. Currently, control is offered for over 250 instruments from more than 25 different vendors and is extended to instruments other than HPLCs. Control is also provided for ICs and GCs (a full list of instruments supported will be supplied on request). Table 2 shows some of the most common instruments that can be controlled by Chromeleon. The next section describes the workflow for setting up the Chromeleon software to control any of these instruments, and how it is possible to eradicate all the disadvantages associated with the traditional environment. Timebase Concept A typical chromatography instrument is a collection of different modules, therefore a top level instrument container is needed that is used to store all the different module information. In Chromeleon the name of that container is a Timebase. This name was chosen because a collection of different modules must all share one common characteristic the system time. For example, pump gradient changes must take place at a specific time and this is often related to the time that the autosampler sends the inject command. Table 2. Common Laboratory Chromatographic Instruments That Can Be Controlled by Chromeleon Type Manufacturer Instrument IC Dionex All instruments HPLC Dionex All instruments Agilent 1050, 1100 (including DAD* control) Waters Alliance (including DAD* control) Shimadzu LC-10 and LC-2010 Merck / Hitachi LaChrom Gilson Most modules. For example: 333, 334 Preparative Pumps 231 Autosampler, 156 Detector GC Agilent 5890, 6850, 6890 Perkin Elmer Autosystem (XL), Clarus Varian 3400, 3600, 3800 Thermo FOCUS, TRACE * DAD: Diode Array Detector Because the base property that is common among all modules is time, the name of Timebase was chosen to define a collection of modules. Registering an Instrument with Chromeleon All instruments must be connected to a Chromeleon Instrument Server. The type of connection is dependant upon the instrument. For example, Dionex instruments are generally connected using the more modern USB interface, whereas an Agilent 1100 can be connected using HPIB or LAN. Instrument connections are registered through the Chromeleon Server Configuration application. Step 1 is to create a timebase the master name for the collection of modules which make up an instrument. Step 2 is to register the different modules with this timebase. The Chromeleon Server Configuration application guides a user through each of these steps (Figure 2). 4 Instrument Control and Data Acquisition with Chromeleon

5 Figure 3. Structure of a timebase directory. A. Create a Timebase C. Define the connection settings B. Select an Instrument/ Module. D. Define the instrument settings Creating a Timebase Directory As soon as a timebase is registered in Chromeleon, a timebase directory is created (Figure 3). The name of the directory is the same as the timebase name preventing the possibility of duplicate timebase names. The directory contains a sequence named manual. This is used to store manually acquired data. The directory also contains a folder named audit where the daily audit trails are stored. The name of the daily audit trail always uses the format yyyymmdd, where yyyy is the year, mm is the month, and dd is the day. So the file name for audit trail for the 18th of May, 2005 would be The audit trail is extremely comprehensive and stores all instrument events such as: Instrument settings current status of the instrument (pump settings, sampler settings, etc.) Changes to settings any changes to the instrument settings such as changes in flow rate, changes to detector wavelength, etc., are logged (along with details of the user making the change) Warnings and errors all warnings and errors (such as pump shut down due to pressure limits being exceeded) are logged in the audit trail Figure 4 shows a typical audit trail. In this example the audit trail is showing the initial instrument settings. Graphical Control Interfaces for a Timebase E. Instrument connection completed Figure 2. Registering an instrument with Chromeleon. Figure 4. Daily audit trail for an Agilent 1100 timebase. Technical Note 67 5

6 Once a timebase is registered, it is simple to create a graphical control interface. In Chromeleon these are called panels, and all Chromeleon installations come with a prepared library of panels (Figure 5). Panels show all instrument settings, including an online signal display. If the instrument includes a diode array detector it is even possible to view the 3-D plot in real time. Panels also show the audit trail so it is easy to track changes or see any warnings/errors. Connecting a Panel To a Timebase Once a panel has been chosen it must be connected to the relevant timebase. Connections can be made either locally or across a network (Figure 7). As soon as the connection is made, Chromeleon automatically notifies the user of any problems. For example, if a panel containing commands for a refractive index detector is connected to an instrument which has only a UV detector, a warning will automatically be displayed. Figure 5. Standard Chromeleon panel library. The library provides a panel for most instrument configurations, but it is a simple task to create new panels. Figure 6 shows a typical panel for an Agilent 1100 HPLC System. Figure 6. Panel library for the Agilent The panel for the Agilent 1100 demonstrates most of the main features about Chromeleon panels. That is: It is possible to have multiple windows to display module specific information (the pump settings were activated by clicking on the Settings button). Figure 7. Different connection options for timebases. Connecting to a local timebase (top), and connecting to a timebase through the network (bottom). 6 Instrument Control and Data Acquisition with Chromeleon

7 Full Customization Supported Panels can be designed to fit any laboratory workflow or any specific user requirements. For example, Figure 8 shows a basic panel for any HPLC. It contains no options for changing any of the instrument parameters. Instead, it shows users a basic workflow that they must follow in order to use the instrument. Figure 8. Basic instrument interface. Full customization is mainly used to ensure that the most important instrument commands and information is displayed prominently. For example, when an instrument is used to collect fractions, any commands relating to starting and stopping fraction collection would be placed in a prominent position. This feature is one of the major benefits provided by Chromeleon panels. It means that a single control interface can be designed for all laboratory chromatography instruments, thus providing lower training costs training time is reduced as users need only learn one interface. Additional Graphical Control Interfaces for Dionex Instruments A special class of panels exists for Dionex instrumentation called panel tabsets. Panel tabsets offer some advanced features that are not available for standard panels. Automatic Panel Tabset Creation Panel tabsets are created automatically based on the instrument settings in the server configuration. All the user has to do is specify for which instrument server the panel tabsets are needed, and Chromeleon will automatically create these for all Dionex instruments that are connected. Figure 10 shows a tabset containing two automatically created panels for a Dionex Summit HPLC system and a Dionex ICS-3000 IC system. These can be expanded or reduced using the buttons next to the timebase name (Figure 11 shows an expanded panel tabset). Instrument Independence Panels are designed to be as independent of instrument type as possible. This makes it possible to use panels designed for one instrument type as an interface for any other instrument type. For example, if a panel is designed to show an autosampler sample tray, it will automatically show the relevant tray design for the instrument to which it is connected. This can be seen in Figure 9. Figure 10. Automatically created panel tabsets. Figure 9. Rack display changes for the same panel connected to different instruments: sampler rack for a Dionex Summit HPLC (left) and sampler rack for a Waters Alliance HPLC (right). Technical Note 67 7

8 Figure 11. Expanded panel tabset. Working With a Panel Tabset A panel tabset contains the following tabs: Home Provides an overview of the system Sequence control Provides an overview of the currently running sequences Tab per instrument module (e.g., pump, sampler, etc.) provides the main instrument settings for each module This special type of panel makes it easy to switch between modules and instruments. It is also possible to use this panel type with the touch screen technology offered by tablet computers. Instrument Control Methods Control panels are used for on-line instrument control and monitoring. For off-line control, instrument control methods are used. In Chromeleon, they are called program files. Figure 12. Pump Options for the Dionex P680 pump. In addition, the options offered in individual dialogs are activated/deactivated based on the instrument server configuration. Figure 12 shows the Pump Options for the Dionex P680 pump. A Maximum Flow Acceleration value can be set for this pump, but a Maximum Flow Deceleration value cannot. To ensure that a user does not set an invalid value this option is automatically grayed out. Editing a Program File All program files can be viewed as a text display (Figure 13). This shows all instrument commands that must be executed as well as the times of the execution. Any invalid commands are shown in red, making it easy for users to locate and modify them. Any command can be modified simply by selecting it and pressing the F8 key. For invalid commands, Chromeleon automatically Program File Wizard Program files can be created using a built-in Wizard that guides users through the main steps required to create a working program file. The Wizard automatically shows dialogs that are based on the instrument configuration. For example, if the instrument has no column oven, a column oven screen is not offered. Figure 13. Program File text display (invalid value highlighted in red). 8 Instrument Control and Data Acquisition with Chromeleon

9 Figure 14. Detailed command options along with value limits. displays the appropriate command dialog along with the allowed values for that command (Figure 14). Simple and intuitive with which to work, this text display allows easy creation of complex methods. For example, to create a method that shuts down a system simply modify a file so that the necessary shutdown commands are included (Figure 15). Figure 16. Sampler Device View in the Program Editor. Transferring a Program File With Chromeleon, it is easy to transfer a method from one instrument to another, even if the instruments are from different manufacturers. Figure 17 shows a program file for a Dionex Summit system containing a quaternary pump that has been linked to an Agilent 1100 with a binary pump. In this example, all pump commands relating to the percent C (%C) and percent D (%D) values are shown in red. Since there are no C or D eluent lines in the Agilent 1100, these commands are irrelevant. Such irrelevant commands are then easily deleted in order to correct the program file for the particular instrument. Figure 15. Basic shutdown method for a Dionex Summit instrument. Additional editing options are provided for Dionex instrumentation and selected third party instruments. These options, called Device views, are displayed on the left-hand side of the program file editor and make it simpler to locate and edit device specific commands in the program file. For example, the user can immediately view and edit all the major sampler commands by simply clicking on the Sampler device view icon (Figure 16). Figure 17. Program file for a Dionex instrument that has been transferred to an Agilent Technical Note 67 9

10 Sample Lists Program files are not used in isolation they need to be linked to specific samples. Chromeleon provides this functionality through sequences. A sequence contains the list of samples that must be injected, along with the relevant vial position and injection volume and associated program file(s). Figure 18 shows a typical sequence. Common Data Format Because all data are now acquired by Chromeleon, it becomes easy to compare data from different instruments. Chromeleon stores all data in the same format so there are no tedious import or export procedures. For example, Figure 19 shows an overlay of two chromatograms. One is of a four-component mixture analyzed by a Shimadzu LC-2010 and the second is from a similar mixture (slightly different concentration) analyzed by a Dionex Summit HPLC. In both cases, the chromatographic instrument method was the same. In this example, the difference in retention times is due to the lower gradient dwell volume of the Dionex Summit HPLC. 1 2 Figure 18. Example sequence. It is possible to have more than one program file associated with a sequence. This allows for different samples to be analyzed under different conditions, and for the inclusion of specialized program files, such as shutdown files. Figure 19. Overlay of two chromatograms from (1) a Dionex Summit HPLC and, (2) a Shimadzu LC On-line Changes to Instrument Parameters It is possible to change the instrument settings while the sequence is running. If the program file is modified, the changes take effect for the next sample in the list, not the sample currently running. Changes can be made to the current sample from the control panel and must be confirmed by the user. These changes are then logged to the audit trail so they can be tracked backward. Sample lists can also be modified during data acquisition, however details of a currently running sample cannot be modified. Example modifications include: (1) adding samples or deleting existing samples, (2) updating sample names and injection volumes, and (3) updating sample positions. 10 Instrument Control and Data Acquisition with Chromeleon

11 Benefits of Chromeleon Instrument Control The main benefit offered by controlling instruments with Chromeleon is increased productivity and laboratory efficiency. This is accomplished through: Increased Data Compatibility All data is stored by the same application so it is easier to compare data from different instruments. Increased Method Compatibility The uniform control commands ensure that transfer of a method from one instrument to another is simplified. Reduced Training Costs Instead of training users on multiple applications in order to control their instruments, they need only be trained on Chromeleon. Reduced Validation Costs Instead of validating multiple applications, they need only validate Chromeleon. Reduced Error Chromeleon panels can be customized so that operators are only shown the information they need reducing the possibility that they will send invalid commands to the instruments. With Chromeleon, laboratories are not restricted to choosing an instrument from Dionex, but are free to choose instruments best suited to their requirements from over 25 different manufacturers. The driver development process used by Dionex ensures that all instrument control drivers released to customers are extensively tested and validated. Laboratories can use Dionex third party drivers with confidence. With this range of options available, Chromeleon is an ideal solution for controlling instruments from a wide range of different manufacturers. Chromeleon and Summit are registered trademarks of Dionex Corporation. Clarus is a registered trademark of Perkin Elmer. Alliance is a registered trademark of Waters Corporation. Passion. Power. Productivity. Dionex Corporation 1228 Titan Way P.O. Box 3603 Sunnyvale, CA (408) North America Sunnyvale, CA (408) Westmont, IL (630) Houston, TX (281) Atlanta, GA (770) Marlton, NJ (856) Canada (905) Europe Austria (43) Belgium (32) Denmark (45) France (33) Germany (49) Italy (39) The Netherlands (31) Switzerland (41) United Kingdom (44) Asia Pacific Australia (61) China (852) India (91) Japan (81) Korea (82) LPN 1778 PDF 04/ Dionex Corporation Technical Note 67 11