Parallel AI Harware config.vi and Labview/DLL exception

[benoitb]

I develop with Labview 7.0 an application wih a PCI-6023 and a PCI-4472 (RTSI bus connected).
I had exceptions detected by LabView and by Windows when i called the 'AI Harware config.vi' VI. I think it appends when 'AI Harware config.vi ' is called at the same time for the 2 boards (see the attached file 'test.llb').

In the test.llb file, you can find an extract of my code (init the 2 board in parallel in a loop for test).

I found a solution for my application (init the board one by one). But can someone explain me why exception occured ? I think that if it is not allowed by the driver (NI-DAQ) to init 2 board at the same time, the driver must lock the access and not generate an exception.

Thanks.


Ben.

[Kerouac]

Hello,

Your issue is due to the fact that the NI-DAQ Traditionnal driver is not multi-thread. That is to say, you cannot call in parallel NI-DAQ functions in your application (generate exception errors) . The NI-DAQ calls need to be sequentialize by wiring for example the error cluster between the NI-DAQ VIs.
A solution to your issue is to use the same programming techniques as described in the LabVIEW examples (Help menu >> Search examples... then Browse to Hardware Input and Output >> DAQ Traditionnal >> Multi-device synchronization examples.
I join also an example for LabVIEW:
*Synchronizing the NI PXI-4472 with E Series Analog Output
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B8C3238E1CF054DDE034080020E74861&p_node=DZ52007

Another
solution to your issue is to use the NI-DAQmx 7.3 driver which is multi-thread. This release of NI-DAQ supports the PCI-4472 and the PCI-6023E. Multi-threading allows the user to perform different tasks simutaneously (like configuration of 2 devices).

Hope this helps.
Matthieu Gourssies
National Instruments France

[benoitb]

Thanks for your answer.

I was thinking that NI-DAQ was multi-thread. It is so easy with LabView to write Vi with parallel call to NI-DAQ function that lot of pepole may have the same problems.

Regards.

Ben.