hardware synchronization of square pulses

[kmargaris]

I have a USB6221 DAQ. I want to generate two identical square pulses. I need the second pulse to start after a pre-specified time delay from the first (micro to milliseconds). I will then combine the two signals with an OR gate and the output should look like the green line in the image. It is important for the separation time to be hardware controlled. How can I do that in Labview?

 

[Kevin_Price]

If you only need the 2 pulses, it seems like you could do this by setting the "initial delay" parameter to be longer than the "low time".   "Initial delay" defines the very 1st delay/low time, the "low time" parameter defines all subsequent ones.

-Kevin P

[kmargaris]

Thanks for your reply.

I should have mentioned that it is a pulse train I need not two individual pulses.

[DAQduck]

Hi,

one solution is to set up two counter channels in "CO pulse time". The first one generates a train containing the first pulse(s), the other the second pulse(s). Both have to be set to "continuous samples". Adjust the relative delay between them by specifying the initial delay of the second channel. Then you use DAQmx Start Trigger in "Start Digital Edge" mode to choose an input line to supply a trigger pulse to, and also specify whether it's a rising of falling flank. Use "DAQmx Timing" in "implicit mode". Start the task and supply a TTL to the specified input line once.That should be all.

Alternatively you can set both counter channels to output only a single pulse. Then you set the trigger source of counter 1 to an input line, and the trigger source of counter 2 to the output of counter 1. Then you use a "DAQmx Trigger" property node to set the "Start.Retriggerable" property for both channels to "true". Now the Start signal can also occur in irregular intervals, and the pulse sequence will still be produced with the proper delay, but on demand, once for every trigger signal. That how it works for me.

Cheers

DAQduck