Remote control of the ROHDE&SCHWARZ Vector Network Analyzer

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1 Remote control of the ROHDE&SCHWARZ Vector Network Analyzer Behrouz Touri & Werner Henkel 1 Introduction Almost all the professional Vector Network Analyzers (VNA) and Spectrum Analyzers (SA) have the possibility of being controlled remotely using GPIB ports. The VNA in the TrSyS lab can be controlled using the RSIB and GPIB ports which are located at the back panel of the VNA. There are several motivations for remote controlling of those devices, but the most important is the possibility of fetching measurement data by the remote computer and use other program packages such as MATLAB, Octave, LabVIEW,... to process the measured data and also the possibility of performing automatic measurements remotely. In Fig. 2, one can see two ends of a typical GPIB cable connector. GPIB (which stands for General Purpose Interface Bus) is a means of communicating data over short distances which was originally proposed by Hewlett-Packard (HP) 1 and is mostly used for measurement equipment. Since this kind of cables and connections became popular for many electrical measurement units, the Institute of Electrical and Electronics Engineers (IEEE) standardized this bus under the name of IEEE Standard Digital Interface for Programmable Instrumentation, IEEE-488. Figure 1: View if the front panel of the GPIB gateway in Wireline communication lab. In order to work with this bus, one simply connects the device which has GPIB socket to a GPIB input port of a PC or a GPIB gateway. Regular computers 1 Also known as Hewlett-Packard Instrument Bus (HPIB) 1

There are several motivations for remote controlling of those devices, but the most important is the possibility of fetching measurement data by the remote computer and use other program packages

2 do not have GPIB ports, but there are several manufactures which produce GPIB cards (PCI, ISA, external,...) for PCs. In our lab, instead of a GPIB card, we use a GPIB gateway. A GPIB gateway is connected to a GPIB device on the one hand and to a LAN on the other hand. The remote computer can connect to it using LAN connection. The front panel of the GPIB gateway in the lab is shown in Fig. 1. Along the GPIB gateway in the lab there is a software which emulates the GPIB port on the computer. Hence, when this software is installed properly and set correctly, from the front-end applications viewpoints, such as MATLAB and LabVIEW, the Network Analyzer seems to be directly connected to the computer with a GPIB connection. This software is already installed and set properly on all our lab computers. Figure 2: A view of the two endings of a typical GPIB cable 2 Remote Control using MATLAB In order to communicate with the device using MATLAB, you should define a GPIB object such astestobj properly. Generally, in order to define a GPIB object, one should use the command gpib( vendor, boardindex, primaryaddress) where vendor is the manufacturer of the gpib board and boardindex and primaryaddress are two numbers. For our device, the argument vender should be set as agilent. For the boardindex and primaryaddress you should run the Test & Measurement Tool program in MATLAB. 2

The front panel of the GPIB gateway in the lab is shown in Fig. 1. Along the GPIB gateway in the lab there is a software which emulates the GPIB port on the computer.

3 For this, first be sure that the Network Analyzer is already powered on. Then run the command tmtool at the command prompt of MATLAB. A window as the one in Fig. 3 should appear. Figure 3: View of the Test & Measurement tool window In that window, explore Hardware and then click on GPIB. Then, a window will show up on the right side of the menu. In that window, hit the Scan button. If everything is set correctly and the GPIB gateway and the network analyzer is working properly, then a device called Agilent Technologies (agilent) should be found. You can see the boardindex in front of the displayed device. For the primaryaddress argument to the gpib command in MATLAB, this should be equal to the address of the GPIB device, specified on the setting of the device. We set this number to 0 on the device. All in all, suppose that the boardindex equals to 7. Then in order to define the GPIB object in MATLAB, you should type test obj = gpib( agilent, 7, 0) in the command prompt (or m-file) of MATLAB. The rest of the process, and how to communicate with the device is the same as the VISA object which is described in the instructions in Remote Controlling of the Spectrum Analyzer. The only worth mentioning issue is that, as described before, most of the SCPI 3

4 Figure 4: View of the Agilent Connection Expert window commands are unique to each device. Hence, in order to communicate with the Network Analyzer, one should use the set of the commands described in its manual. The user s manual of the network analyzer of the TrSyS lab can be find in the Instruments Manuals directory. 2.1 Remote Control Using LabVIEW For connecting to the Network Analyzer using LabVIEW, almost the same steps as in the case of the Spectrum Analyzer should be carried out. The only difference is in the VISA addresses of the Network Analyzer and the Spectrum Analyzer. In order to find the VISA address of the network analyzer, one may double click on a small icon with the word IO in it on the task bar (right-bottom corner) of the windows. Then in the appeared window (Agilent Connection Expert), double click on the Remote (GPIB0) and then click on the ZVR device. Then, a page will appear on the right side of the window, which contains the VISA address of the device (see Fig. 4). For example in 4, the VISA address is equal togpib0::0::instr. 4

The user s manual of the network analyzer of the TrSyS lab can be find in the Instruments Manuals directory. 2.

Figure 5: Implementation of the described example using VISA read and write blocks in LabVIEW. Now, having the VISA address of the network analyzer, we have two options to remotely control the device.

5 Figure 5: Implementation of the described example using VISA read and write blocks in LabVIEW. Now, having the VISA address of the network analyzer, we have two options to remotely control the device. 2.2 General approach This is EXACTLY the same as in the case of the Spectrum Analyzer. The only things that one should change is the VISA address of the device and the SCPI commands of the device. For example, again consider the case that you want to grab the measurement data of the Network Analyzer in the range of 1GHz and 2GHz. Then, one should set the VISA address to GPIB::0::INSTR (supposing that the VISA address of the device is GPIB::0::INSTR). Then, by referring to the User Manual of our Vector Network Analyzer, one will find out that the SCPI command for setting the START and STOP frequency of the swiped frequency range is SENS:FREQ:STAR and SENS:FREQ:STOP and the command for requesting the measured data of the channel 1 is TRAC? CH1DATA. Hence, the application implemented for the spectrum analyzer can easily be modified to the application shown in Fig Manufacturer-implemented function blocks Just as in the case of the Spectrum Analyzer, Rohde & Schwarz implemented a set of block functions for communicating with the ZVR network analyzers. This block functions can be found in the Input Instr Drivers RS ZV Vector Network Analyzers in the function palette of your application and can be used for implementation of an application. 5

For example, again consider the case that you want to grab the measurement data of the Network Analyzer in the range of 1GHz and 2GHz.

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