Digital signal generation in cDAQ- 9477 with 1ms resolution.

[Kumar_B]

I am using cDAQ -9477 Digital card with 9178 chassis (USB) .I have to generate some digital signals for 2 seconds. The signal should be

0 (3ms)  -   1(1ms)  -    1  (2ms)   & repeat the sample 0 (3ms)  -   1(1ms)  …….  upto  2 seconds.

I had generated samples for 2seconds with 1ms duration of each sample.

I am unable to do that with 1ms resolution in cDAQ -9477 Digital card.

Is the above signal generation is possible (each sample -1ms) ?

I am using LabVIEW2009 .I attached the code.

Kindly let me know the suggestions .

[Kumar_B]

Any suggestions ?

[KyleBryson]

Hi Kumar,

Have you tried using the example Cont Write Dig Port-Int Clk.vi?  Also, the DAQ Assistant can be helpful with an application like this.

Regards,

Kyle

[MarkGrot]

cDAQ chassis do not currently support hardware timed tasks for digital modules with >8 lines.  The DAQmx help defines these devices as "static digital I/O modules".  The "Digital I/O Consideration for C Series Devices" section in the DAQmx help describes the capabilities of digital modules on different chassis.

Unfortunately this means you are stuck with static (software timed) generation.  Over USB this will affect the accuracy of your signal.  You won't be able to achieve the signal you are trying to generate with the current support.  Static generation will max out at roughly 1kHz, but Windows can introduce a large amount of jitter.  What you really need is a hardware timed task.

This is a feature that could be added in the future.  I recommend submitting a feature request, though I know that doesn't solve your problem now.