retriggerable AI with delay

[paulj]

I need to set up an acquisition application that will sample two AI channels at a specified time delay after each occurrence of an external trigger. It sounds simple enough, but I haven't found something that works well. I am using a PCI 6023E card. Any advice?

[rgharrison]

Hi pauli,

The best way to accomplish this is to use a counter and route the counter output as the scan clock (sample clock in DAQmx). To accomplish this, use a counter configured for retriggerable pulse generation. You should set the source of the counter to be the internal 20MHz clock and the gate of the counter to be your trigger source. There will be 2 parameters when configuring pulse generation on counters; pulse spec A and B. You will want to configure your delay in A and your pulse width in B. This should create a delayed pulse based on your trigger. The next step would be to route the output of the counter to the scan clock (sample clock in DAQmx). You can use Route Signal in LabVIEW or Select_Signal in C.

The best place to get started is b
y looking at some of the shipping examples with NI-DAQ. They will be in the NI-DAQ directory for C/C++/VB and they will part of the LabVIEW examples under the Help menu.

Anyway, hope that helps. Have a good day.

Ron

[paulj]

Thank you, Ron. You have been most helpful.

Paul