09-19-2017 06:48 PM
I am using the NI 6259 DAQ to read a quadrature encoder. The datasheet for the 6259 states that any PFI designated channel can be used as a counter/timer; however, there are only two channels that seem to work. When I set up one of the other PFI channels, the encoder read out on NI MAX changes from 0 to 36m, but nothing in between. It appears to be set up exactly the same as with the two channels that work. Any suggestions on what I could be missing? Are not all PFI channels created equal?
Solved! Go to Solution.
09-20-2017 09:13 AM
Hello jsholl :
As fas as I understand your issue is related to the number of clocks on the NI-6259. See the page 13 from the attached link:
DEVICE SPECIFICATIONS NI 6259
09-20-2017 10:50 AM
I understand that the number of counters is limited to 2 on the 6259. In the documentation, it states that any PFI channel can be used as input for the counter. When I attempt to change which PFI channel is used for the encoder set-up, it still seems to act like a digital input instead of a counter. Is there something special I have to do to designate the channel as a counter?
09-20-2017 11:35 AM
It appears I need to change the default NI-DAQmx counter terminals. Right now CTR 0 A is set as PFI 8 (Pin 37) and CTR 0 B is PFI 10 (Pin 45). I want CTR 0 A to be PFI 14 (Pin 1) and CTR 0 B to be PFI 12 (Pin 2). How can I change the default set-up?
09-20-2017 02:06 PM
This post shows how I did it in labview:
https://forums.ni.com/t5/Multifunction-DAQ/quadrature-encoder-based-triggering/m-p/3128787#M85838
I don't know if you can change the PFI terminals in MAX, at least for me they're hard coded to defaults. It's easy to do in labview/c/.net though using the A/B/Z inputterm settings.
09-28-2017 10:36 AM
We were able to fix the problem in our VI. A staff member remembered it was referenced in the VI. Once we changed the channel referenced to the desired one, we were able to read the encoder.