generate reconfigurable and retriggerable pulse with x series (PCIx 6321)

[martin.clausen]

Hi,

I am trying to generate a single retriggerable pulse, which must remain reconfigurable while the task is running.

On the m series device (PCI 6221) I have been able to do so using the following configuration:

generate finite pulse train with one pulse on ctr1 with implicit timing, digital trigger on falling edge on PFI1, property node: retriggerable=true; start task; update the counter with the property node for high/low time, after checking if its ready for a new value

With the new x-series I get the error -200557 in the property node where I update the counter and the pulses remain generated with the initial settings.

How can I make the program work on the x series?

Thanks for any suggestion in advantage!

Martin

[Neil_S.]

Martin,

Yes, you have run into an issue that we have seen before.  This was reported to R&D (#230677) for further investigation.  It seems like incorrect behavior.   Working around the issue will depend on your application.  It may be possible to employ additional counters to get similar behavior.  Where does the trigger come from, and do you know what the next pulse specification should be before the application starts?  If so you might be able to use a buffered counter output to get similar behavior, but it might not work for your specific application.  Could you give us more details about where the trigger comes from and where the update values come from?

Regards,

Neil S.

NI-DAQmx R&D

[martin.clausen]

Neil,

thanks for your reply! The trigger comes from a line of port 0 of the same DAQ device. The timing on port 0 is fixed and the signals are regenerated by the device itself. The pulsewidth is not known during startup, since the values are calculated at run time by a PID control. Therefore I assume that a buffered counter output is not an option. There are 2 free counters on the device. The timing should be accurate with in something like 100us.

Regards,

Martin