05-27-2020 06:42 PM
Hey Everyone,
I have a GPS unit that sends a PPS (Pulse Per Second) to NI 6229. The PPS signal is a TTL signal of 3.3V. The PPS signal is sent to NI 6229 at 1Hz. The issue is that the NI cannot seem to read the PPS signal. I have looked at the oscilloscope, and I can see the signal. I don't know what's going on. Please help!! Just an assumption, could the reason why NI card cannot read the signal is due to the speed of the TTL signal.
05-28-2020 08:21 AM
How are you trying to read it? What is the pulsewidth of the signal?
Open up MAX, open a test panel for your device, choose counter i/o edge counting mode. If the pulsewidth is very small, this will be much more effective than polling the signal via standard digital input.
-Kevin P
05-31-2020 07:46 PM
Thank you. I just realized that it was a timing issue. The GPS unit was sending PPS signal in microsecond while i was reading in millisecond. I had to convert the PPS Signal to millisecond.
Thank you