generating two synchronized, finite and retriggerable pulses with different frequencies

[Mew1]

Hi,

I am using a PCI 6031E card with SCB-100. I am working on generating a pulse train for a camera used in optically accessible test engine. The engine has a crank angle encoder producing pulses with freq 30-60 kHz (0.2 deg resolution, range 1000RPM - 2000RPM, is working in the attached program as source of ticks). The spark time pulse is a trigger for the camera pulse train. The pulse train should be generated for specified number of cycles (or number of trigger events). The camera should obtain a pulse train that after trigger has 20 pulses with very high frequency and after that 4 pulses with low frequency. When the engine cycle ends, the program is retriggered for next cycle. I was thinking about generating the pulses on two ctr outputs and then multiplexing it by simply joining the cables (If it would be possible to generate such a pulse on one line I would be very happy). I managed to generate the 20 initial pulses but unfortunately it is not possible to generate second pulse due to this. I was also thinking about generating the second pulse on digital output, but the card does not allow due to this. I was also trying to use a pause trigger, but the program showed error, that there cannot be a start and stop trigger (also tried with reference digital edge trigger).

Somebody have idea how to solve this problem ? I would appreciate any help.

In the program the trigger is attached both to PFI and digital input line. Source of ticks is the encoder

Thank you for support

Greg

[ValkoA]

Dear Mew1,

Unfortunately, you are correct in your research on the limitations of the E series DAQ cards. You require two counters for a finite pulse train (the first one generates a continuous train, the second one gates the first one). And DO operations are software-timed only.

If the receiver circuit is robust enough, you could try creating the pulse train with analog IO. The device has two analog outputs with 100 kS/s update rate and 5 mA output current. You can output a sequence of +5V and 0V as appropriate, and time it with the encoder input as an external sample clock. 

Kind regards:

[Mew1]

Dear ValkoA,

Thanks for reply. We already solved the problem, the camera can be set to add 4 low frequency pictures after pulse train. Nonetheless, thanks!

Kind regards

Grzegorz Kruczek

[ValkoA]

Dear Grzegorz,

I'm glad you managed to solve the problem. Thanks for letting me know.

Regards: