NI-488: Command requires GPIB Controller to be Controller in Charge

[guanger1105]

Hi,

I have a power supplier from Kepco. When I tried to run the VI send by the company, I always received the error:

Error 1 occurred at Scan From String (arg 1) in KepcoDCPwr Query Voltage Limit.vi->KepcoDCPwr Interactive Example.vi

Possible reason(s):

LabVIEW:  An input parameter is invalid. For example if the input is a path, the path might contain a character not allowed by the OS such as ? or @.
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NI-488:  Command requires GPIB Controller to be Controller-In-Charge.

I use LABVIEW 8.2   Do you know how to solve this? Thanks

[Dennis_Knutson]

One reason to get error code 1 from the scan from string is when the input string is empty. The VI you posted is in LabVIEW 5 and I can't open it with 8.5 but try communicating to the instrument in MAX. Send the query that is in the subVI and see if you get a response. You can also open the subVI and probe the string input to the scan from string and see if there is anything there.

[Rimasaurus]

Hi,

Error 1 is also described in the GPIB Error Codes and Common Solutions KnowledgeBase.  This document describes common GPIB errors, possible causes, and solutions.  Good luck!

Regards,

Rima

[guanger1105]

Thank you for the help.

Yes, in the SubVI, after the VISA reading, the responding string buffer is empty. That caused the problem. But it happened randomly, sometimes the buffer is not empty.

The labview I use is v.8.2, it can open the VI, but I don't know whether it's due to the version.

[Dennis_Knutson]

It probably has nothing to do with the version of LabVIEW. It just might require a delay between the VISA Write and the VISA Read. When the VI was originally written, everthing ran a bit slower (computers, etc.) and that could be the reason you are seeing an occasional problem now.

[guanger1105]

Yes you are right. I put a delay between the VISA Write and the VISA Read and fix the problem. Thanks.