Triggering digital output on NI 9401

[svazquez22]

Hello all, this community has been a big help in the past and for that, I thank you. Now I come with another question. I am trying to set up a program that will send a TTL output after detecting an external trigger. It might be trivial but I am having trouble accomplishing this. I am getting an error that says:

Error -200294 occurred at DAQmx Start Task.vi:7220001

Possible reason(s):

Not enough samples were written to satisfy the initial data transfer request condition.
To successfully start a generation, increase the number of samples initially written to the buffer before starting. Alternatively, decrease the number of samples required to start by changing the data transfer request condition.

End of Data Sample Number: 0
Minimum Value: 0

Task Name: _unnamedTask<0>

Again, I apologize if I am making a silly error that might have been addressed before but I can't see what is going wrong here. Any help would be appreciated, thank you.

[ZYOng]

That's because you didn't write any data to the DAQmx Write VI.

You can use Pulse Pattern.vi to generate pulse data. For example as shown in the attachment, using a sample rate of 1kHz, each sample point is 1ms. Setting a delay of 100 points and a width of 200 points will generate a pulse with 100 ms of offset and 200 ms of high time.

[svazquez22]

Unfortunately I don't think this is going to apply to my scenario. I am trying to use a voltage change from an outside source to trigger a digital output task. The "Daqassist digital.vi" works as intended and I am trying to take code from that vi to my "Digital output testing.vi" as I want to put it in another bigger program later. I have attached my vi files that will hopefully clarify things. Thank you.

[svazquez22]

I could still use some help with this issue as I haven't been able to figure it out still.