Problem in controlling Keithley 236 using a GPIB/USB cable

[Jo Radtke]

Hello, I would like to use my PC to control Keithley 236 SMU to do some simple I-V measurements (sweeping voltage and measure the current). If you can give me some advice to my problems, I will be very very grateful.

Situation: I have a PC (windows XP) with labview 7 and 8.2 and 8.5 installed, a GPIB-USB cable, and a Keithley 236 SMU. I want to do very simple I-V measurements (sweep voltage and measure current). The GPIB-USB cable was previously installed into the PC to control some other multimeters (voltage meters). Now, all these multimeters are removed. The PC is ONLY connected to the Keithley 236. The status on the GPIB-USB cable shows to be in color green.

I have downloaded a labview program suitable for Keithley 236/237/238 from the website of Keithley (attached, 237 SwpMeasl-repeat.llb). But no matter how I tried, it cannot communicate with the Keithley...

Do you know why??? Any suggestions is welcome. I am a beginner in labview. Many thanks for letting me know.

[Ben]

Start with MAX and do a Find devices to get the SMU to show up. If it doesn't don't waste time with LV. Fix it there first.

If it works take note if its name and use that in he Keithley code.

Ben

[Jo Radtke]

Hi, thanks for the reply. The connection is fine. Now I suspect that, maybe, because I am using a Agilent GPIB/USB cable (instead of a GPIB card) and therefore I cannot use a program downloaded from Keithley which contains GPIB write/read commands... Can anybody please confirm this?

[Dennis_Knutson · Accepted solution]

No, you cannot use NI GPIB functions with an Agilent card. You will have to change to using VISA functions.

[Jo Radtke]

Thanks Denis, just a further question: in the future, with another PC, if I purchase the NI GPIB USB high speed cable, (1) will I be able to control instruments like Keithley 236 source meter? (2) will I be able to use the labview program downloaded from Keithley with GPIB write/read commands ??

Many thanks for letting me know. 

[Ben]

If...

You can write down all of the buttons you have to mash in the proper order to get the SMU to give you the measurment you want...

Then

The driver from Keithley exposes all of those buttons and settings so it is just a matter of putting "Tab A in Slot A" in LabVIEW.

Ben 

[Dennis_Knutson]

Any 488.2 controller can communicate to any 488.2 instrument. It just so happens that the old driver for the instrument was written with proprietary NI GPIB functions. A portable instrument driver is written with VISA functions. To do that with your existing code is actually pretty simple. Most of the work can be done with a couple of search and replace actions. You can do that or wait until you get an NI controller.

[Jo Radtke]

Thanks. I have replaced all GPIB write/read functions to VISA write/read functions. Please see the attached programs for both the unmodified and the modified program. The unmodified one was downloaded from Keithley. The one named "...mod.vi" is the one I modified. 

However, it still doesn't work. It's not a communication problem (I've texted a simple VISA write with the correct address and the command N1X, the PC did communicate with Keithley 236). So, the problems must be in my labview programs. Did I made mistakes while changing these functions??? Can someone please help me to have a look???

Many thanks for letting me know. 

[Ben]

I have to bow out at this point. I would have to start pushing my ready made solution and that is is outside the price range of a free forum.

I will turn this over to the the rest o f the team.

Ben