Start trigger synchronization between x-series multifunction daq and ni 9219

[halep55]

Hello,

I would like some help and maybe some clarification on an issue I have since I do not have a ton of experience programming in LabVIEW.

Equipment:

X-Series multifunction DAQ (PCIe 6361) that I interface with using a BNC 2110 terminal block.

USB 6003 multifunction DAQ

NI 9219 in a single slot cDAQ 9171 chassis

My experiment has 3 pressure transducers, 2 thermocouples, and a solenoid controlled through a relay.

The 3 pressure transducers are connected to the BNC 2110 and are measured in a single daqmx task with the same timing settings and in a finite samples acquisition configuration. However, one of the three pressure transducers is special, I physically split that signal into two and monitor the second signal with the USB 6003 at a lower sampling rate and in continuous mode.

The two thermocouples are hooked up to the NI 9219.

Ultimately what happens is I start the VI and monitor that special pressure transducer on the USB 6003, when I am happy with the pressure, I press a physical push button attached to a PFI line on the BNC 2110. The push button triggers a counter to send a single 1 second pulse to the relay/solenoid valve, and simultaneously starts the data logging on all three pressure transducers for 2 seconds of data collection.

My problem is routing the same start trigger signal to the NI 9219 so that the start time for collection on the thermocouples is synchronized to the opening of the solenoid valve. Reading the NI 9219 manual tells me that it has no PFI capability that I can gather. The single slot cDAQ 9171 does not have PFI lines either like some higher end 8 slot chassis.

Is there a hardware solution I am missing? Is there a way to achieve this same task in software? I've attached my VI, I hope it is clear. The top task is the NI 9219 task, the second from the top is 3 pressure transducers on the PCIe 6361. The third from the top is the counter for the solenoid and the bottom task is the continuous acquisition of that special pressure transducer.

Thanks for the help!

[Kevin_Price · Accepted solution]

My first thought is to send the trigger signal in as a 4th AI channel (configured for plain voltage) on the 9219.  Then you can pretty easily examine the data to identify the trigger point to within 1 sample interval reliably.  No software approach can beat that precision or match that reliability.

-Kevin P

[halep55]

Wow great. Thanks Kevin, that was a very simple and elegant solution, wish I had thought of it before.