Simulate Signals DAQMX

[TMDATA]

I am using Simulate Signals which is generating a 125hz square wave with a 10v amplitude, then sending that singal to DAQ Assistant for an analog out.  Somehow the frequency seems to be changing to the DAQ Assistant analog out, therefore I am not running 125hz.  I notice this when the samples per second (hz) in the Timing section of Simiulate Signals is increased or decreased.  Is this just a sampling miss match??  I am sampling analog in data with another DAQ Assistant to capture data at 10,000 samples/sec(trying to capture accurate data of a very fast valve), then writing to a spreadsheet.  Thanks for any help

[Tom_W_[DE]]

Hi TMDATA-

What type of DAQ card are you using?  How are you verifying that the output frequency is not the rate you specify?

I have tested with the attached VI and seen good results when measuring digital frequency on a counter of my MIO M Series card.  You will notice that I have chosen "Use Timing from Waveform Data" in the DAQ Assistant Express VI.  This ensures that the timing information requested in the Simulate Signals VI is passed to the DAQ Assistant for task timing control.  I have verified that the actual output frequency closely follows the frequency requested using the Simulate Signals Express VI.

Please give this method a try and if you continue to have problems please let us know how you're verifying the output frequency.

Hopefully this helps-

Message Edited by Tom W. on 09-08-2005 04:30 PM