How to generate a digital (TTL) output on a PFI?

[zientist]

Hi all, I am a bit new to labview.  I am using a USB 6251 BNC.My VI generates a sine wave (freq=23Hz) that drives a device then records the output which is synchronised with the sine wave.  What I would like to do is to generate a TTL output that is synchronised with the sine wave.  Since my DAQ card has BNC outputs, I wanted to generate the TTL output on a PFI.  I am finding it very difficult to do.  Is this possible? Can somebody please help me out.My VI is attached.ThanksZientist


1 Synch-Sine-Acq-Save-TTL-incomplete4.vi:
http://forums.ni.com/attachments/ni/250/42214/1/1 Synch-Sine-Acq-Save-TTL-incomplete4.vi

[S_Hong]

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[zientist]

Hi S_Hong Thanks for your advice and doing the VI.   Unfortunately I can't open the VI as I have labview 8.2 not 8.5.  Perhaps you could sent me a jpeg pic of the block diagram.Zientist

[S_Hong]

Hi zientist, Here's the same code written in 8.2. Please let us know if you have any question.


Synch-Sine-Acq-Save-TTL-incomplete4 (Modified 8.2).vi:
http://forums.ni.com/ni/attachments/ni/250/42308/1/Synch-Sine-Acq-Save-TTL-incomplete4 (Modified 8.2).vi

[zientist]

Hi S_Hong, Thanks for your reply and sending the 8.2 version file. I understand what you mean.  I have a question though.  Since you said that it is imperative to have the output signal ready to go when the input trigger is connected (I know you meant use the errors to do that), but is the following VI appropriate (attached).  Because even if I don't link the errors, as long as i trigger the analogue output signal after the signal is generated it seems to work fine.  Is there something wrong in this logic? Zientist 


1 Synch-Sine-Acq-Save-FFT-5.vi:
http://forums.ni.com/ni/attachments/ni/250/42313/1/1 Synch-Sine-Acq-Save-FFT-5.vi

[S_Hong]

Hi zientist, To reiterate, since you will be triggering you analog output off of the AI start trigger, you will need to finish configuring and start your AO task so that it is ready to receive the AI trigger. So in other words, you will need to start your AO task before your AI task. As long as you can ensure this, you will not have any problems.