Data Acquisition - HP/Agilent 4192A Impedance Analyzer with Prologix USB GPIB Interface

[Dogbertius]

I am trying to interface an Aglient (formerly HP) 4192A Low Frequency impedance analyzer with LabView 8.2 for data acquisition (DAQ) purposes. I want to be able to perform frequency sweeps and extract the data so that I can plot it.

I am using a ProLogix GPIB USB controller, which provides a virtual serial port (COM5, in my case) so that I can communicate with the 4192A device. I have already install the ProLogix device and connected the 4192A device to my PC with it, and have been able to communicate to the 4192A with propietary software (http://www.thegleam.com/ke5fx/gpib/readme.htm#prologix) and GPIB commands with similar software.

I cannot get the VI for the ProLogix controller to work though (http://prologix.googlepages.com/Prologix_GPIB_Sample.vi), but should I need to, since the virtual COM port works for sure? I just want to be able to communicate to the 4192A through LabVIEW. I tried downloading drivers for the device from NI.com (http://sine.ni.com/apps/utf8/niid_web_display.download_page?p_id_guid=E3B19B3E923F659CE034080020E74861), and it's an example program library LLB file, along with an MNU file. Do I have to do anything special to install this driver, or can I just open the library file and run the sample VI's? When I run the sample VIs, I select the proper COM port (COM 5) and hit the "Run" button, and the VI indicates that data was sent, but not received.

Any help on this would be appreciated. Even if I have to code a program from scratch in C, it'd be fine. I just want to be able to communicate with the 4192A and extract data measurements from my sweeps.

Thanks in advance.

[Dennis_Knutson]

When you use the example VI from Prologix, exactly what command do you send and what is the error code that is returned?

Are you trying to run the 4192 example when you say you enter a com port value? That certainly won't work because the 4192 code is written with GPIB functions.

[Dogbertius]

This clears up quite a bit already. Is there any simple way to communicate with these devices in the serial manner I have available (ie: GPIB opensource code, etc), or such? I've read through the manual for HP 9825A/9835A computers, which I assume used some manner of assembly language.

I don't think that the Prologix device is capable of acting directly as a GPIB controller, it just acts as a serial <=> GPIB controller that translates the commands, so this could be tough.

[Dennis_Knutson]

In theory, the example LabVIEW code you get from Prologix should work just like their other program. The example is using the LabVIEW serial interface. I will repeat my earlier question - What was the exact command you sent to the 4192 and what was the error code returned?

[Dogbertius]

i believe the command was

?ign

and the error code was a 10-digit number. I will be able to get the exact info in a day. Thanks for the help so far.

[Dogbertius]

Well, the solution ended up being to go a different route. Your original reply was right, the VI is designed to work with an actual GPIB controller. In the end, I wrote some serial port code that allows me to send GPIB commands over the serial interface. All is working now. Thank you!

[Arko]

Hi, I just got one of these Prologix USB GPIB Interfaces and I'm trying to interface it with labview. Is there anyway I can get a copy of that VI you made?

[Dogbertius]

I don't have the VI. There's a good one on NI's site that works with an actual ISA GPIB controller card, maybe you could modify it?

I scrapped the LabView route, and wrote my own data acquisition and plotting program from scratch in C++. Not too shabbey, but the source is closed. Sorry.

Message Edited by Dogbertius on 08-21-2008 01:37 PM

[Arko]

I would write my own or modify the NI but I do not know the commands to get data from my picoammeter. I'm really unfamilary with the GPIB interface. What commands can I use to ask for a reading? I tried sending ++ver and it spit out a version number of the Prologix, so that proves there is communication. I sent a ++read but I get no response.

[Dogbertius]

There's a manual on the ProLogix web site, explaining a lot of the commands the USB GPIB controller uses (eg: ++read eoi    is what you probably want to use), but you will also need the original manual for your pico-ammeter as well. You'll have to google that one, and it could take a little while. Chances are you'll find a scanned PDF of it somewhere along the line.