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synchronising digital waveforms and counters

I have created the attached VIs: DigitalPulse.vi creates a digital pulse train, and ImagingSequence uses DigitalPulse.vi to output a digital pulse train and a counter pulse train.  I would like the counter pulses to happen "within" the digital pulses, with a controllable positioning in time.  I have "fudged" this by playing with the initial delay on the counter train, but would like to know how to synchronise this properly?  Any ideas?
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Message 1 of 7
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Hi Bruce,

 

I would recommend looking into DAQmx triggering.  You could set up one task to trigger off the other and use a trigger delay to time the pulses correctly.

There are many synchronization examples built into LabVIEW - these can be found under Help >> Find examples >> Hardware IO >>  DAQmx

 

Hope this helps,

------
John.P | Certified LabVIEW Architect | NI Alliance Member
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Hey Bruce,

 

It sounds like what you want to do is to gate the pulses.  You can check out here for something similar. I have also created an example in one of the community forums for gating a signal on a PXI chassis here.  But I am not exactly certain if this is what you are looking for.

 

Cheers, Matt

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This looks close to what I want.  I notice that you use two counter channels rather than a counter and a digital.  The system I am working with requires many signals to be sent by LabView and I do not have enough counters for everything. Is there a way to trigger a waveform on the digital lines for tasks which do not require a high refresh rate?  I have been trying to do this, but can't seem to incorporate the DAQmx Timing.vi
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Hey Bruce,

 

Can you describe what you are using to make your measurements?  i.e. the platform (PCI, cRIO, PXI, etc) as well as what you might be using your counters for.  Most boards should have at least two counters associated with them which can be shared with other boards.  Off the top of my head, the only way that I can think of actually having the counter pulses occur within the digital pulse is to generate the digital pulse on whatever line you are using, and then use the trigger property node to pause the counter when the sampled digital line goes high or low.  I am not sure what latency to expect in the system for this method, but it should work about as well as routing the internal counter.  m

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Thanks for your help, sorted out something satisfactory myself
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Can you put you your conclusion?
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