Error Reading from HP 66xx PSU

[Dennis_Knutson · Accepted solution]

The idea is that a service request would be issued when the measurement is complete. Instruments also have a GPIB query called OPC? which stands for Operation Complete? Both are intended remove the need for variable wait times between the command that starts the measurement and the read.

[Dennis_Knutson]

What I forgot to add was that the service request is a physical line. The OPC? is data.

[rx8pilot]

That nugget of information is really great! Thanks Dennis. I will looking into whether or not the Te AD007 supports service reqests. Having the OPC as a backup to keep the timing workable/reliable is good to know. 

The quick and dirty test simply taking out the service request seems to work but it could get ugly when the system complexity and GPIB traffic starts to build up. Thank you for the help! That was more obscure than I was expecting. 

[rx8pilot]

I have searched for some usable information on using service requests to manage GPIB timing. Not too surprising to find why it is so useful and so many drivers use them. The interface I am using , Tektronix AD007 is a little shy on exact details, but claims conformance to IEEE 488.2 and uses VXI-11 protocol over ethernet. It does not explicitly say if it supports SRQ or not, but it seems that it would most likley support this fundemental of GPIB communications.

I have tried testing with a few other devices and run into the same problems - service requests are never serviced and therefore generates and error. What I am looking for now is a way to test the service request function - maybe a bad cable or instrument in the chain is holding the line? 

Is this an unusual problem, or does this come up all the time? I have no problem buying a different ethernet adaptor, but would rather not until I have found the smoking gun. 

[rx8pilot]

Another update....

I took the AD007 Ethernet adaptor apart to look for any physical damage that would short/open the SRQ pin (#10 on GPIB). All looks good visually and I was also able to confirm the GPIB controller is a genuine  National Instruments chip. This gives me some confidence that the issue is more likely in the software. Hard to imagine that Tek would spend the money on that controller and not configure it for SRQ. 

In addition, I disconnected all the instruments and just tried one at a time to eliminate any one instrument or cable. All configurations of cable and instrument crater when waiting for service request. Continuing the hunt for something that is holding the service request.......

[NickyNoodle]

@rx8pilot, I understand that something is timing out, but just to be sure, what exact error are you receiving?

[rx8pilot]

The error starts here, after the Visa Enable Event:Service Request

Error code: 

-1073807339

VISA Enable Event in Agilent 66XX Series.lvlib:Read Meas.vi

Hope that helps shed some light....

[NickyNoodle]

I would like to suggest that you start a new thread in our forums if indeed your original issue has been resolved and an answer has been marked.  We suggest this so that each thread has one issue and one solution, keeping them more organized.

I have found an example in LabVIEW that you can find by going to Help > Find Examples... > Hardware Input and Output > VISA > SRQ Event Handling.vi.  I have attached an image of the block diagram.  I would suggest trying to run this example, passing in the commands to measure the current or voltage on your third party device, and making sure that you are not getting any errors and the raw data output makes sense.  If this works, then I would try to adjust your code to reflect the working example.