GPIB connection with Keithley 2400 source meter

[laputagd]

Hello, I am trying to write a short Labview program to read from Keithley 2400 source meter. The purpose of this work is to source a current and monitor the voltage value vs. time. The GPIB card is Keithley KUSB-488A.

The GPIB address of the source meter is 24. And I use "GPIB read" to get data from the source meter. My question is how do I know the output from "GPIB read" is an array or string? And how do I know which output is the voltage ( I suppose there will be several signals output from the source meter).

I am totally new in Labview, so any suggesions will be highly appreciated.

[smercurio_fc]

You should first download the driver for the instrument if you don't already have it. This will make your life easier. You can find a driver for the instument in the Instrument Driver Network. Direct link to driver.

General answer to your question: The GPIB Read always returns a string, so it's never an array. Whether or not the string should be parsed to create an array completely depends on the response.

Note: Use of the "GPIB Read" function is discouraged in preference of using VISA. The VISA Read function is functionally equivalent to the GPIB Read function.

[Dennis_Knutson]

The first thing you should do is download the existing driver for that instrument at http://sine.ni.com/apps/utf8/niid_web_display.download_page?p_id_guid=25B255F3AA83660EE0440003BA7CCD.... The second thing is that you cannot use the GPIB functions with that GPIB controller. The low level GPIB functions are only for NI GPIB controllers. You can use non-NI controllers if the vendor provides a VISA library for it and you enable the tulip passport in MAX (Measurement & Automation Explorer). If you don't want to use the driver, then you would have to use the VISA functions. A query always returns a string. The format of the string would be explained in the instrument manual.

There have been numerous recent posts about the 2400 and the exact same task you describe. This must be a class project. You might want to search the forum for '2400' and go to Keithley's web site for some examples.

[laputagd]

thanks a lot for the suggestions! There was a driver (CEC 488) shipped with KUSB-488A and it is already installed.

I am sorry to hear GPIB read can not be used with this KUSB-488A, I should order a NI card instead. Can anybody help me write a simple program to read current from Keithley 2400 and plot it into a graph? It is very hard for me to get started. Thank you!

Jinjun

[laputagd]

One more question: if I use VISA functions, can I use RS-232 instead of GPIB card? RS232 cable is very cheap while a GPIB card costs $500. What's the benefit of using GPIB ? Thanks.

[Dennis_Knutson]

I wouldn't give up on the GPIB controller if you already have it. If it's a CEC, you should be able to use it with LabVIEW. I believe CEC is now part of Measurement Computing (http://www.measurementcomputing.com) and they say their driver is compatible with LabVIEW.

If you don't have the controller yet, then a serial connection will be much cheaper and yes, you can use VISA with RS-232. You will also have a much slower connection. You will aslo be restricted to how many instruments you can control. With GPIB, you can control multiple with a single controller. With serial, you need a port for each instrument.

[laputagd]

Thank you Dennis, I will continue work on the GPIB programm.

[Nek]

National Instruments says they own MCC

http://www.ni.com/news/releases/apr0504.htm

[Dennis_Knutson]

Old post and old news.

[hanna80]

Hello, I am trying to write a Labview program that reads from a Keithley 2400 SourceMeter. I want to source a current and monitor the voltage over time. I am using a GPIB card.

I downloaded the Certified LabVIEW Plug and Play (project-style) Instrument Driver but some how the examples I find here reset the source range. It looks like the source range gets reset every time I measure resistance even tough that’s not what I want to measure - the program does that.

It would be great if you can help me on that problem, since it looks like you had a similar problem last year.