I'm using LabView along with a 4156c to attempt to some some simple resistance measurement sweeps, preferably in the Van der Pauw configuration. However, if attempt to configure SMU3 or SMU4 I get an illegal command error as follows:
>> Instrument reports
>> +181,"Illegal setup. Invalid command"
>> +0,"No error"
Where the no error is there because it reads the error buffer until it returns "No error."
If I change the exact same VI to affect SMU1 or SMU2 it works perfectly, but I am unable to configure 3 or 4. Does anyone have any insight into this problem?
Have you tried using NI Spy Capture? Below is a KB link on the procedure.
This should give you some insight into this issue.
I hope this helps.
it could also be that VAR1 has been assigned twice, once from your sweep with 2 SMUs and also as a leftover from a previous measurement. When programming the 4156 from the front panel, this is not possible, but with remote commands this is possible.
To avoid that, program the unneeded SMUs as CONST.
That is definitely the problem I run into if I don't configure SMU3, as it seems to default to VAR1. However, I can't configure SMU3 at all, so it's stuck as VAR1. I'll report back with anyone from the NI SPY, hopefully today.
I had the same problem and tracked it down to the series resistance command in the ConfigureSMU VI (PAGE:.....SRES)
Agilent explained that the 4156C will not accept a series resistance for SMU 3 or SMU 4.
The following is a quote from an email from Agilent support:
This means that it should always work on SMU1. It will work for SMU2 if you don’t have a 41501B expander frame. However if you have a 41501B expander that adds SMU5, then the series resistance works with SMU5 instead of 2.
For any NI people reading this, removing the offending command, or prohibiting it from sending SRES to SMU3 or SMU4, from the VI will allow the it to work without throwing errors.
Hope this helps.