gen dig pulse train usb 6008

[labnoob]

ok, i have been trying to get my app working. its geneating 2 square waves signals from the epxress vi waveform, and im trying to output these waves to the dgii out of my usb6008. but with no such luck. any ideas to why? its says i can only choose "on demand" and not continous. not sure where im going wrong. i get this error.


Possible reason(s):

I/O type of the physical channel does not match the I/O type required for the virtual channel you are creating.

Physical Channel Name: Dev1/ctr0
Virtual Channel Name: Dev1/ctr0
I/O Type Required for Virtual Channel: Counter Output

Task Name: _unnamedTask<FFE>



i have also tried opening the example "gen dig pulse train" and runing it. again with no luck. i get this error

Error -200430 occurred at DAQmx Create Channel (CO-Pulse Generation-Frequency).vi:2

Possible reason(s):

I/O type of the physical channel does not match the I/O type required for the virtual channel you are creating.

Physical Channel Name: Dev1/ctr0
Virtual Channel Name: Dev1/ctr0
I/O Type Required for Virtual Channel: Counter Output

Task Name: _unnamedTask<FFE>

[Dennis_Knutson]

The answer is pretty simple. Your USB-6008 has software timed digital I/O only and continuous sampling depends on hardware timing. The device also doesn't have a counter output so that won't work either. With software only timing, to ouput a square wave, you have to do a DAQmx Write of a logic 0, then a DAQmx write of a logic 1, and repeat. The frequency is going to be pretty low, and both it and the period will be subject to quite a lot of variation.

[labnoob]

hi thanks for replying. could you possibly show an example?

[Dennis_Knutson]

Here it is. It's about as simple as it gets.

Message Edited by Dennis Knutson on 12-05-2006 08:06 AM

[labnoob]

ah, thanks mate. not sure if this setup is going to be "good " enough for my requirements. what are the vis inbetween the write vis.

also, would the 6009 do what i need it to do?

[Dennis_Knutson]

That's the Delay function. The labels get messed up when copying and pasting into paint.

No, the 6009 has the same specs as the 6008 for digital i/o and counters. You can go to http://sine.ni.com/nifn/cds/view/main/p/sn/n24:USB/lang/en/nid/1036/ap/daq and click on any of the USB devices and view the specs.

[labnoob]

thanks for that so what would you recomend for my code attached. cheapest!!

[Dennis_Knutson]

I can't view the VI and even if I could, I would be hesitant to make a recomendation based on a program. Especially a program written by such an inexperienced LabVIEW programmer. The program wouldn't necessarily tell anything about what is actually required. If you can define the hardware requirements in some detail, then you can call your local NI sales engineer for assistance.

[labnoob]

ok. thanks for all your help anyway.

[labnoob]

ok. off the record, do you think this "may" suffice? all i need is two square waves generated from the express waveform vi to be outputed from the daq. building an isolation/preamp is no problem.

http://sine.ni.com/nips/cds/view/p/lang/en/nid/203189