VISA Error −1073807303 | Unable to queue the asynchronous operation because there is already an operation in progress.

[markcstephens]

I am doing some asynch visa reads over the lan and every so often I will get an exception:

−1073807303 | Unable to queue the asynchronous operation because there is already an operation in progress.

To clear this error requires me to reboot the machine running the GPIB card as well as the machine I am developing on!

This is not really an acceptable solution as the GPIB machine is remote.

Is there any way I can clear any pending operations?

This problem is quite easily reproduced with C:\Program Files\National Instruments\MeasurementStudioVS2003\DotNET\Examples\Visa\SimpleAsynchronousReadWrite\VB example supplied with VISA.

The VISA version is 3.6

Best Regards,

Mark

[JasonSmith]

Hi Mark,

Could your provide us with the following information about your system?

1. Which GPIB adapter are you using?  It sound like it is a plug-in-board in another computer?

2. Do both computers have NI-VISA 3.6 installed?

3. Which operating systems are the computers running?

4. Which version of NI-488.2 is installed on the computer with the interface board installed?


Thanks!

Jason Smith
Applications Engineer
National Instruments

[markcstephens]

Jason,

Thanks for your reply.

As I only have a ISA GPIB board, I had to put it in an old P3/850. Thanks to Visa I can share the resources on the LAN.

The board is an AT-GPIB/TNT

Both machines are Running NI-Visa 3.6

Due to the GPIB driver limitations the ISA machine runs Windows 2000 Professional and the development machines are running Windows XP Professional.

The NI488.2 version is 1.70

I think I fixed the problem however, I noticed one of the instruments was behaving oddly when addressing other instruments. I replaced the cable and the problem went away.

Could it have just been a faulty cable?

Many thanks,
Mark

[Albert.Geven]

I've seen faulty cables but much more often problems with old connectors, (not the best contact over years)
and I've seen a lot of cabling that does not adhere to the standard:

e.g. more than 4 m coupled to one instrument, and a lot of instruments not turned on (half of them should be on)

the standard says not more than 2m cabling but sometimes it even works with 12m.

In fact the standard is more critical than most working setups but, yes it could be the cable.