How do set the Clock Signal as a Digital Out in the C-API?

[neurostu]

Sorry about the typo, I am in fact using the M Series device (6254)

[John_P1]

After doing a little digging it turns out that this is actually a known bug (CAR 166393) and was fixed in DAQmx 9.0.  If you look at the error message, you'll notice that the terminal that the driver is attempting to export is 10MHzClock rather than 10MHzRefClock (which is the actual name of the terminal).

Unfortunately we don't have a version of DAQmx for Linux that includes the bug fix.  Using DAQmxConnectTerms like Steven mentioned should be a suitable workaround--I prefer Export Signals usually but due to the bug it's not an option in this case.  The appropriate name for the 10MHz clock terminal is /Dev1/10MHzRefClock.

Sorry for the inconvenience, if you're still having any problems exporting the signal using DAQmxConnectTerms please don't hesitate to let us know!

Best Regards,

[neurostu]

John P,

Thanks for the information. I was beginning to think I was going crazy.  With regards to the bug do you know if there is either a plan to issue a patch, or if there is an estimated ship date for the linux version of DAQmx 9.0

[John_P1]

I wouldn't count on a patch for the older driver version.  The workaround of using Connect Terminals should be sufficient for the bug that you (re)discovered.

If you want to start a discussion about DAQmx for Linux, I think it would probably be best to post to the idea exchange. 

Best Regards,

[neurostu]

So I altered my code to use the ConnectTerminals instead of ExportSignal and instead of throwing an error the program (crashes?) hangs the entire computer. 

Here is the test code I'm running:

http://c.pastebin.com/14Zy8Ehr

The only output I get is what I've added on line 21.

Both the way I've written it up and with lines 19,20&22 commented out and line 23 not commented out. 

Originally I had two cards in the computer connected via an RTSI cable, I removed the RTSI card which had no effect, I completely removed the 2nd card which also had no effect...

I've also tried a variety of output channels though all have been /Dev1/PFI# channels.

[Steven_K.]

Hi neurostu,

On further research, only Red Hat Enterprise up to version 3 is supported. There is a knowledgebase article about the lack of support for Red Hat 4 (and likely by extension Red Hat 5) that show similar symptoms. Here is a link it it:

KnowledgeBase 3RKD66TY: Red Hat Enterprise Linux WS 4 support of DAQmx on Linux

It has a potential workaround by recompiling the kernel, however this version of Red Hat is not supported by NI.

[neurostu]

Steve K,

Thanks for taking the time to help me debug this.  I was worried that this was infact the problem we were facing.

thanks

Stuart

[neurostu]

Last night I recompiled my kernel to use an 8K stack and that fixed all of the problems. I am now finally able to start exporting signals. Thank again for the great support!