Hardware start trigger for synchronized software timed loops

[bvisser]

Hey all,

With a 9188 Chassis I'm using a fast software timed loop to control some flowrate with the signal from a counter while adjusting a valve voltage accordingly. In another slower software timed loop I record data from a serial port and TCP connection. Both loops are synchronized by using the "Synchronize Timed Structure Starts VI".

From another data aquisition system (non-NI) I can receive a digital start trigger when data aquisition on that device is started.

My question: How can I use this external start trigger (connected to a PFI line of the 9188 Chassis) to start both software loops? I figured that I would be able to use the external start trigger to start a dummy DAQmx task before one of the software loops, but this seems far fetched and also not to work 🙂

If anyone could get me on the right track, that would very much be appreciated.

Regards,

Bram Visser

[bvisser]

Hey all,

I found a solution using the DAQmx Read and DAQmx Task properties. The loop now starts when a trigger is received. By synchronizing this loop with other timed loops, they all start at the same time.

The stop (or reference) trigger is used to stop the loop and send a stop notifier to the other loops.

Hope this may be of use to someone.

Regards,

Bram