SRQ in LabVIEW 2011

[ScottDobbins]

I'm trying to use LabVIEW with VISA instrument control and SRQ.  Attached is my VI.  I have every reason to believe the device dependent code I'm sending to a Keithley 3706A DMM/Switch is correct and should cause the device to assert SRQ.  I suspect I'm doing something wrong in LabVIEW.  Any suggestions?  Thanks.

[TomBrass]

Without studying the Keithley 3706A manual in detail, I can't give you a definite answer.  You are using 3 seconds for the timeout.  Are you certain this is long enough?  If you haven't already, try giving it a much longer timeout, like 10 or even 20 seconds, to see if an SRQ is ever asserted.

If that is not the issue, then you are missing a command to send to the instrument.  For example, you might need to send something like *SRE.  It looks like you are sending a "request enable" command, but that might not be exactly the same thing.  The other thing to watch out for is the order of commands.  Some Keithley instruments are extremely picky when it comes to the order of the commands that you send.

Hope that helps!

Tom

[ScottDobbins]

Tom:

Your response is much appreciated.

Initially, I had no timeout specified, and it defaulted to 25,000 ms (25 seconds).  25 seconds went by, and it timed out.  The scan I'm doing completes in less than 100 ms, so timeout length is not a factor.

The problem has to be

1) I'm doing something wrong in LabVIEW, or

2) I'm not sending the right commands to the 3706A.

An apps engineer at NI told me my LabVIEW code looks correct.  In fact, I'm following an example of SRQ I got from the NI website.

I'm working with Keithley to see if my commands are correct.  This is the most likely thing causing the trouble.  I downloaded Keithely's LabVIEW driver for the 3706A.  There's tons of code that do different things, but unfortunately, SRQ is not one of them.

Thanks again.