Application Note Boonton 4540 Remote Operation Modes Mazumder Alam Product Marketing Manager, Boonton Electronics Abstract Boonton 4540 series power meters are among the leading edge instruments for most accurate RF power measurements. Features like high dynamic range, very fast rise time and effective time resolution of 200 ps provide the greatest details in signal waveform analysis. The 4540 power meter is the best instrument for capturing, displaying and analyzing RF power in both the time and statistical domains. Many applications need measurements to be controlled remotely. This document describes various remote control options and the details to configure them.
Boonton 4540 Remote Operations The 4540 comes standard with GPIB, LAN (Ethernet), and USB device (B-Type) interfaces which can be used to remote control the instrument. When GPIB, LAN or USB assume control of the instrument, the keyboard entry is automatically disabled, and a remote indicator will be shown at the lower right side of the screen. Below are the details of the configuration for each interface. USB Configurations The 4540 USB interface is configured automatically by the host computer when the instrument is connected. There are no instrument configuration settings to perform. The instrument will identify itself by using the Boonton Electronics provided USB cable. The 4540 communicates via the USBTMC (USB Test and Measurement Class) protocol for USB control, which allows GPIB operation to be emulated over the USB. Once the host computer has identified the instrument and initialized the USB parameters, communication may begin. Typically, the host will use VISA to provide the interface layer between the instrument and the remote control software. The menu report item System > I/O Config > USB > View Buffers displays the current contents of the instrument s internal USB send and receive buffers. This feature is very useful for analyzing programming problems. The buffers show what has most recently been received from the controller and what response string has been sent to the controller or is waiting to be sent. Fig 1: Boonton 4540 front panel. Fig 2: Boonton 4540 rear panel shows the interfaces Application Note Boonton 4540 Remote Operation Modes 2
GPIB Configurations The 4540 GPIB interface is configured using the System > I/O Config > GPIB menu. The primary listen/talk address (MLTA) can be set to any value from 1 to 30 inclusive. The value assigned must be unique to each GPIB device. Secondary address is not implemented. ASCII talk and listen terminators are not required or supported the 4540 supports the industry standard EOI method of terminating strings send to and from the instrument. The talking device must assert the EOI bus signal on the GPIB bus when transmitting the final character of the message. This function is performed automatically by most GPIB controllers. LAN Configurations The 4540 LAN interface is configured using the System > I/O Config > LAN menu. The instrument may be set to automatically accept its IP address and associated information from a DHCP server, or the configuration data may be entered manually. The 4540 communicates via the VXI-11 protocol for LAN control, which is a TCP/ IP based format that allows GPIB operation to be emulated via the LAN. Once the LAN parameters have been configured, the controller can perform a broadcast and find all instruments on the subnet, or the instrument s IP address (whether manually or automatically assigned) may be used to assist the remote control software in locating and connecting to the 4540. Fig 4: Boonton 4540 display showing the System>I/O Config>LAN menu Fig 3: Boonton 4540 display showing the System>I/O Config>GPIB menu If a CR and/or LF are present at the end of an incoming GPIB message, it will simply be ignored by the 4540. The menu report item System > I/O Config > GPIB > View Buffers displays the current contents of the instrument s internal GPIB Listen buffer or Talk buffer. This feature is very useful for analyzing bus communication problems. The buffers show what has most recently been received from the controller and what response string has been sent to the controller or is waiting to be sent. Typically, the host will use VISA to provide the interface layer between the instrument and the remote control software. The menu report item System > I/O Config > LAN > View Buffers displays the current contents of the instrument s internal LAN send and receive buffers. This feature is very useful for analyzing programming problems. The buffers show what has most recently been received from the controller and what response string has been sent to the controller or is waiting to be sent. Application Note Boonton 4540 Remote Operation Modes 3
Boonton 4540 SCPI Remote Programming Commands The 4540 Series instruments can be remotely controlled using commands that follow the industry-standard SCPI programming conventions. All of the functions of the 4540 Series are accessible remotely via SCPI commands. The complete description of SCPI commands can be found in Section 5 of the instruction manual. The list is grouped by SCPI subsystem or IEEE488.2 function, and includes a detailed description of each command.rf power envelope. These are: peak power, pulse power, average power, pulse width, risetime, falltime, overshoot, pulse period, pulse repetition rate, duty cycle, top amplitude, bottom amplitude, offtime, edge delay and the delay between two RF pulses. Below are some example commands with syntax and a description: MEASure:POWer? DISPlay:PULSe:TIMEBASE Valid Modes: Description: Syntax Returns: Automatically set to Modulated Mode be fore measurement Return average power using a default instrument configuration in Modulated Mode and dbm units. Instrument remains stopped in Modulated Mode after a measurement. Measure[1 2]:POWer? CC, Average power in dbm, Where CC is the measurement condition code. Valid Modes: Description: Pulse Mode Note: There are separate timebases for the Pulse Mode and the Modulated Mode. The arguments selected are saved and restored independently by mode Set or return the Pulse Mode timebase in seconds/division. The 4540 has fixed timebase settings in a 1-2-5 sequence, and if the argument does not match one of these settings, it will be forced to the next highest entry. Optional units: minutes. FETch:ARRay:MARKer:POWer? Valid Modes: Pulse and Modulated Modes Syntax: DISPlay:PULSe:TIMEBASE <numeric_value> Argument: <numeric_value> = 10e-9 to 10 s, (1-2-5 sequence), 30 s, 1, 2, 5, 10, 30, 60 min Description: Syntax: Returns an array of the current marker measurements for the specified channel. The array consists of the average, maximum, and minimum power and peak-toaverage ratio between the two markers, powers at both markers, and the ratio of the two markers. Note the peak-to-average ratio and marker ratio are returned in db for log units, and percent for linear units. FETCh[1 2]:ARRay:MARKer:POWer? DISPlay:PULSe:TSPAN Valid Modes: Description: Pulse Mode Note: There are separate timebases for the Pulse Mode and the Modulated Mode. The arguments selected are saved and restored independently by mode Set or return the horizontal time span of the display in pulse mode. Time span = 10* Time/Division. Optional units: minutes. Returns: CC1, Pavg, CC2, Pmax, CC3, Pmin, CC4, PkToAvgRatio, CC5, Pwr@Marker1, CC6, Pwr@Marker2, CC7, Mrk1/Mrk2 ratio. Where the CCn s are the measurement condition codes for each measurement. Syntax: Argument: DISPlay:TSPAN <numeric_value> <numeric_value> = 10e-8 to 100 sec in a 1-2-5 sequence, 300 s, 10, 20, 50, 100, 300, 600 min Application Note Boonton 4540 Remote Operation Modes 4
Example of Remote Measurement for Pulse Mode The following example gives some guidelines for remote programming of the Boonton 4540 Series. These program fragments use the SCPI command syntax, and may be used for remote control via the GPIB, USB or LAN interfaces. Note that the LAN and USB emulate GPIB behavior, so bus triggering, SRQ and polling operations may be slightly different. When maximum accuracy is required, an automatic sensor calibration (AutoCal) should be used. This steps the sensor through a series of calibrated power levels and builds the sensor s linearity calibration table for its entire dynamic range. AutoCal is performed using the internal 50 MHz step calibrator. Below is an example of remote measurement for a periodic pulse waveform by using remote commands with the GPIB bus trigger to initiate a single measurement. CAL1:INT:AUTO? Calibrate the sensor connected to the Channel 1 { WAIT 2 MINUTES } Allow sufficient time for the longest anticipated calibration. { READ flag } Read the result flag and proceed accordingly. Now for a single measurement in pulse mode related commands are as below: *CLS Clear all status registers CALC:MODE pulse Set for pulse measurement mode TRIG:SOUR sensor1 Set trigger source for sensor1 input signal ABORT Measurements STOP and triggers go to idle. MARKer[1 2]:POSItion:TIMe <value> Set or return the time of the selected marker relative to the trigger. INIT:CONT off Set for single, triggered measurement INIT:IMMEDIATE Single measurement trace. (Single sweep) {send GET} or *TRG Send GPIB Group Execute Trigger (GET) command. One random trace appears in graph mode (start measurement) FETCH1:ARRAY:MARKER:POWER? Returns an array of the current marker measurements for the specified channel. The array consists of the average, maximum, and minimum power and peak-to-average ratio between the two markers, powers at both markers, and the ratio of the two markers. {send GET} or *TRG Send Group Execute Trigger command. No effect; measurement is complete. Application Note Boonton 4540 Remote Operation Modes 5
Boonton 4540 LabVIEW Drivers The Boonton 4540 power meter has a plug and play type of Lab- VIEW driver with supported communication of GPIB, USB and Ethernet (LAN) interfaces. The support software required by the driver is NI (National Instruments) VISA 3.0 or later. The Boonton 4540 power meter can be controlled and measured remotely by using any of the above interfaces with NI s LabVIEW software. In LabVIEW, an instrument driver is a set of software routines (VIs : Virtual Instruments) that control a programmable instrument. Each VI corresponds to a programmable operation, such as configuring, reading from, writing to, and triggering an instrument. Below is an example of pulse signal measurement by using LabVIEW software. Virtual Front Panel (VFP) Remote Application Boonton 4540 has a Windows based remote application to control the instrument and display all measurements via a LAN connection. The Virtual Front Panel (VFP) remote user interface allows simulating and demonstrating Boonton 4540 key buttons via larger computer screen/projector. It is very convenient to capture screenshots and saved them into a PC by using this software especially when the 4540 power meters are in a remote location. Note that the 4540 instrument needs to be turned on manually as this application does not include the ON button. Below is a VFP application example performing a RF power measurement. You can download 4540 instrument driver two different ways. If you are using LabVIEW 8.0 or later, the easiest way is to use the NI Instrument Driver Finder. If you have older version of LabVIEW, then you can use the Instrument Driver Network (IDNet). Fig 6: Boonton 4540 Power Meter display screen Fig 5: Example LabVIEW block diagram for pulse signal measurement with Boonton 4540 Power Meter Fig 7: Boonton 4540 Power Meter Virtual Front Panel (VFP) remote application performing the same RF power measurement Application Note Boonton 4540 Remote Operation Modes 6
How to Capture Screenshots with VFP There is an easy way to capture the measurement screen from VFP software by following the options under File menu and selecting save screen shot option. The capture files can be saved into any picture format and used for different documentations purposes. 5. Click the Find button located in the upper right corner of the VFP application window. If a window with several rows appears, select the 4540 with which you want to communicate. Alternatively, you may type the IP Address directly into the text box labeled IP Address. 6. Monitor the Boonton 4540 using screen capture by clicking the button labeled Repetitive Screen Shot. This button also stops the repetitive screen capture. Note: You can display a variable sized screen capture by clicking the Launch Viewer button. Control the 4540 using the simulated keypad to the right of the screen shot box. 7. In order to update the display careen for the first time, press Start. Fig 8: Virtual Front Panel screen capture and saving option TCP/IP Configuration for VFP Application Below is the procedure for the installation and TCP/IP configuration of Boonton 4540 VFP application: 1. Install the VFP software 2. Connect the Ethernet cable between Boonton 4540 and Desktop / Laptop computer 3. Turn ON the Boonton 4540 and make sure that DHCP is enabled (Go to Main Menu > More > System > I/O Config > Ethernet > DHCP/ AutoIP > ON) Fig 9: Virtual Front Panel (VFP) application showing TCP/IP configuration and start button. 4. Press Start from the VFP application. It will request DHCP service. Note: If the DHCP server on the subnet does not respond, the 4540 power meter will configure itself for AutoIP with an IP address beginning with 169.254.xxx.xxx - If DHCP/AutoIP is set to OFF, the items on the Extension page will be selectable and can be edited by the user. - If DHCP/AutoIP is ON and unit does not configure properly, verify that the network cable is properly connected, as shown by steady green (link) and flashing (yellow activity) LEDs on the LAN connector. If these LEDs do not turn on, try a different Ethernet cable. Application Note Boonton 4540 Remote Operation Modes 7
References: [1] Boonton 4540 RF Power Meter Instructional Manual (http://boonton.com/~/media/boonton/manuals%20and%20software/4540_instructionmanual.ashx ) [2] Boonton 4540 Quick Start Guide (http://boonton.com/~/media/boonton/manuals%20and%20software/4540_quickstartguide.ashx ) [3] Boonton 4540 Data Sheet (http://boonton.com/~/media/boonton/datasheets/4540_series_datasheet_web.ashx ) Wireless Telecom Group Inc. 25 Eastmans Rd Parsippany, NJ United States Tel: +1 973 386 9696 Fax: +1 973 386 9191 www.boonton.com Copyright 2011 All rights reserved. B/APP4540-ROM/0711 Note: Specifications, terms and conditions are subject to change without prior notice.