Working Keithley 236 sweep example, anyone?

[PHacke]

Does anyone have verified working example code for the Keithley 236 using a version of LabVIEW from the last 10 years or so that performs a vi sweep?  Kindly post if so.  While the static DC measurement examples available on the NI website work, the sweep examples do not (for me at least). For example, the vi "Keith 236 Sweep Example" does not pull in the data at the Keith 236 Read Measurement subvi contained therein.  No errors, it just does not pull in the data after the voltage-control sweep has been performed.

[PHacke · Accepted solution]

Figured it out. In the Keith 236 Read Measurements vi, in sequence no. 0, changed the initial read point with the String Subset function from 10 (what it is when downloading from this NI website) to 9 to properly read the "true:sweep false DC" value.  To note, the version of my Keithley 236 (seen in the LED readout at startup) is A03.

[cstorey]

The Keithley 236?  There's a classic!  I one collecting dust in storage and can't quite bring myself to dispose of it quite yet.  I used to have lots of code for them.  They use simple single/double letter commands to setup.  But they are unforgiving if you send a value outside of the expected range or in a format the instrument isn't expecting.  They are also a little unforgiving in the order you send setup commands.

I suggest you check the parameters you are sending for the sweep.  Are they formatted correctly?  Are they withing the I/V limits? 

Then use highlight execution to watch the SMU as it receives commands. Possibly send one setup command at a time and make sure there's no error on the SMU. 

Finally check if the trigger has been sent.  I used to use mine through a 237 trigger unit, helped with syncing 4 SMUs.  I remember something about the software trigger being a bit awkward to figure out. 

Also look out for waits or timeouts in the code or with the GPIB bus.  This is an old instrument, its not fast!  Set timeout to 300s when asking for a few hundred data points.  You can practically hear each bit trickle in!

Post code with save default values and images of errors for more help.

Craig

[PHacke]

Thanks, cstorey.   Like I mentioned in a post above, I figured it out and indicated the solution.

To note, I came across another such Keithley (238 variant) with a later version of firmware (A08), and the NI website- provided LabVIEW software worked fine out of the box with that.