trigger counter manually

[FocusPaul]

Dear community,

I'm struggling a problem with starting a triggered counter task.

environment:
- card: USB-6218 using latest NI-DAQmx driver 9.7
- OS: Windows 7 x64
- dev plattform: MS Visual Studio 2010 (C/C++ language) ... but do not mind if anyone comes up with a Labview solution

card setup:
- retriggerable Counter 0, which starts generating a finite amount of clocks (100 up to 1000) at pre-defined, high frequency (200 ... 250 kHz) when it receives a rising edge on PFI0
- Counter 0 generates sampling clock for two analog output channels (AO0 and AO1, amount of samples is finite due to finity of clocks generated)
- Counter 0 is also output to standard digital pin (PFI 4 / P1.0) and then smoothened (creates constant high on "clock" orr constant low on "no clock")

process:
- NI DAQ card starts outputting on AO 0 and 1 for a pre-defined time
- while clocks are generated, my smoother keeps PFI 4 high
- when generation is over, the smoothed counter 0 output generates a falling edge (from "last clock impulse" to "no more clocks"), which triggers a device X
- after device X is done with its work, it generates a rising edge on counter 0 input, which starts clock and therefore starts output on A0 0 and 1 again
- and on and on and on ...

problem:
- can't find a way to start the whole loop between NI DAQ card and device X, because I cannot activate the Counter 0 trigger manually
- I cannot order device X to send me a trigger, because it's technically black box ... or call it "dumb piece of electronics" 😉

what I tried:
- creating a digital output task, which output pin reconnects on Counter 0 source pin; doesn't work, because digital ports cannot be shared above task borders on M-series devices; also I cannot attach a single pin to a task (software exception)

Any ideas?

Thank you for reading,

M. Paul

[Adilo]

Hi Paul!

Could you please post some screenshots wih markers of your VI?

The VI itself would also be very helpful.

Best regards,

Adilo

[FocusPaul · Accepted solution]

Hello Adilo,

unfortunately I have no VI screenshot, because it is coded in C.

But I solved the problem:

It is possible to have an external digital output task, which is started while the retrigger task and the analog output task is already running. This task is set programmatically to create a short pulse. The digital output re-connects to the digital input used for triggering.

My mistake was, that my card only has one port of digital outputs, but another task claimed all 8 pins of this port. Now the other task only claims a single pin of the port, so other pins are free for use for additional tasks.

Thank you for reading,

Paul