Hi, I am trying to synchronise data acquisition between a NI cDAQ-9188XT and a 3rd party instrument. The 3rd party instrument puts out a digital synchronisation signal which consists of a short pulse every time it samples followed by a series of pulses encoding a 32-bit integer (see image - sync signal for 3 packets). This integer corresponds to the a serial number recorded along with each packet of data. The instrument samples at a rate of 2 kHz, so the pulse + integer occurs every 0.5 ms and by my rough calculation, each bit of the integer lasts 5 µs. The cDAQ-9188XT will be recording a series of analog channels using LabVIEW, and I wish to record this sync signal along with the analog channels so I can synchronise the two datasets in post processing. There are no spare slots in the cDAQ so I cannot use a digital IO module and I believe the sample rate of my analog channels will be too low to capture the synchronisation signal. The cDAQ-9188XT has two BNC connectors on the chassis which map to the PFI0/PFI1 lines, I would like to know if there is any way to use a PFI line to record this synchronisation signal? Cheers. Pat.

Thinking about this again, if you're content with post-processing the data then you can get by with pretty simple acquisition code (maybe start with a buffered semi period example). This will give you an array of the high/low times of the signal which you would then need to decode into the 32-bit number. Best Regards,

Multifunction DAQ

Record digital sync signal using PFI0/PFI1

Solved!

Nice--great idea with the fractional sampling.

I was mistaken in assuming that the AI sample clock was the same as your device sample clock.

Best Regards,

John Passiak

Message 11 of 11

(1,151 Views)

Multifunction DAQ

Record digital sync signal using PFI0/PFI1

Re: Record digital sync signal using PFI0/PFI1