Keithley sourcemeter resets itself out of 4 wire voltage sense back to 2 wire sense when performing a measurement

[engdev]

The Keithley 2425 sourcemeter LabView driver does not support 4 wire voltage sense mode. I am using direct VISA commands to set the instrument into 4 wire sense, but when the instrument is commanded to perform a measurement, it resets to 2 wire sense. There is significant error in the resultant measurement. Does any one know of a way to keep the 4 wire or remote sense active?

[mikeporter]

It looks like you are going to have to dive into the driver and find the command that is setting the thing back to 2-wire mode. My hunch is that the drivers do a reset on the device after performing the reading. I have seen drivers before that were written that way--though personally I don't see why you would want them to do that. Assuming you have a manual on the beast the job will be messy, but not too hard.

Who actually wrote the drivers? NI or Keithley?

Mike...

[engdev]

Thanks Mike.

Keithley wrote the drivers and the way they have done it makes identifying a particular command difficult. The driver makes a call directly to a dll and there are no parameters available to either enable or disable the reset function.

Dave

[Ben]

Welcome back Mike!

You have been missed.

Ben

[mikeporter]

Ok, it sounds like you are going to have to recode things completely to get rid of the DLL. If you have the documentation it will take a bit of messing around but still shouldn't be too bad. The big thing to remember is to not try to create one huge driver that controls everything in the instrument. Break the functionality down into logical subsystems like basic configuration, output control, triggering, etc.

Mike...

[mikeporter]

Hey Ben;

Good to hear from you. You won't believe why I haven't been on. I got a new computer and couldn't remember my forum user name... DUHHHH... I have heard there are two signs of old age. Losing your memory is the first and the other is... uh, what was I saying?

In any case I was researching a problem last night and ran across an old post of my own, so I'm back...

Mike...

[engdev]

It sounds like I have the top guns working on this one!

Keithley has offered to look at the code, so I'll let you know how I go.

Thanks again,

Dave

[Ben]

Please keep us posted on what you find.

Ben

[wha@atmel]

Hi Ben,

nice to meet you here again.........

But - let me give some comment about K24xx - SMU's. I started using the K2400 SMU in 1995; at this time no
LabVIEW driver from KEITHLEY was available for this Instrument. I took the manual and wrote my own driver by
use of the GPIB - commands. Later I found the "kisrcmtr.llb" .... - all the needed functions for use of this SMU were available ( but in "old style" no use of VISA ).

As far as VISA is not a must for engdev .... you can have this .llb - send a mail to werner.hasche@web.de - I will send it to your private- ( or company- ) address ( 692kB zipped).

Find attached a picture of Frontpanel "K2400 Voltage sweep.vi" - Diodes are measured up to 1 Amp (4-wire-mode in order to avoid voltage drop @ cables ). I think, I have shown this already in a previous thread .....

Engdev, if this sweep-program is something for - let me know - for sure this works in the same way for your Instrument. We have adapted this program already for K2420-SMU (60V/3A) - the Input Ranges of Controls need to be changed.

Regards
Werner

[Ben]

Hi Werner,

Thank you very much for the offer.

If your code works half as good as your FP images looks, it will help me out a great deal.

Ben

PS I will see if I can get you some extra stars.

Message Edited by Ben on 06-30-2005 10:51 AM