Why is Start Trigger Delay not applicable?

Question

Hardware: PCI 6602
Driver: DAQmx 7.4
Programming Environment: ANSI C
Hello All,
I'm setting up a counter output pulse generation task which is to have a start trigger.  To be specific, it is a digital edge start trigger (not an arm start trigger) which I plan to use in retriggerable mode so as to get a single output pulse of specified width for every trigger edge.  Currently I'm baffled as to why the Start Trigger Delay and Start Trigger Delay Units properties do not seem to apply - whenever I try to access them I get an error message saying they're not applicable to the task.  The other properties of interest - Source Terminal, Active Edge, and Retriggerable - can be accessed and modified without any problems.  I don't actually need the delay but am curious to know why it doesn't apply in this case.  Thanks in advance.
Jeff

Answer 1

Hey Jeff-
You will need to make sure that you don't stop the task at any point after the first generation.  Most of the examples use DAQmxWaitUntilTaskDone() to wait for a single iteration, but in your case you want to run through several iterations of the task.  So, you will want to enter a loop after starting to ensure that the task continues to run in the background on the hardware.  I modified the single pulse DAQmx shipping example to include digital retriggerable start triggering.  The empty loop spinning is obviously not ideal, so I'll leave you the choice to implement that as necessary.
Since you're working with retriggerable single pulses, you may also want to be aware of the information in this KB.
Hopefully this helps-
Tom W
National Instruments
Attachments:
DigPulse.c ‏4 KB