PXI-6624 only writes one sample in pulse mode

[raphael.wittwer]

Hello all

I am trying to write a pulsetrain to the counter output of a PXI-6624, however only the first sample is ever written.

My pulsetrain has 50 samples, and with simulated hardware the output "number of samples written per channel" matches that. If I build the application and run the program on the target system it only outputs one sample indefinitely and also "number of samples written per channel" is always 1.

I tried adjusting the value for "numSamplesWriten" in "DAQmx Write (Counter 1D Time 1Chan NSamp).vi" to a non-zero value without any influence. The timing is set to 50 samples in continuous sample mode with implicit timing.

What am I missing, how do I get the counter to go through the array of samples one by one to output the desired timing series?

Thanks in advance,

Raphael

[Kevin_Price · Accepted solution]

I think the 6624 is an older model with an NI-TIO timing chip that doesn't support buffered pulse train output.   The best you can do is to change on-the-fly with software timing.

Note also that finite pulse trains will occupy a 2nd counter known as the "paired counter".   The pairing is set internally, cannot be changed, and goes like:

0<-->1

2<-->3

4<-->5

6<-->7

A newer card like the 6612 can do buffered pulse train output with hardware-level timing, *and* finite pulse trains no longer occupy a 2nd paired counter.

-Kevin P

[raphael.wittwer]

Hello Kevin

thank you for your reply. It really seems it is not possible with this hardware.

Since the hardware is already fixed I will have to think of something else.

Thanks, Raphael