Problems Measuring Frequency using encoder input into a 6036E DAQ

[Biobartman]

I am trying to measure the frequency from an encoder signal (TTL level) using the "Meas Dig Frequency-Low Freq 1 Ctr.vi" example vi. I have the signal going to the pfi gate line (ctr 0 gate on a 6036E DAQ). I am expecting signals up to 5000 Hz, but the frequency is measuring at about random values ranging from 125000 Hz to 100000000 Hz. I tried defining a minium pulse width in the DAQmx Time property node, but I get an error stating the "specified proprty is not supported by the device".

When I try to count pulses or pulse widths using othe VIs, I get very random values that do not make sense.
My signals are not that noisy (+/-0.1 V) so why can't I get the counter to count correctly? What signal level is the counter expecting? What signal conditioning do I need to do to the encoder? Is there a DAQmx property that I can change to set/change the threshold?

Dan

[AnujD]

The easiest way to ensure you can read your pulses is to test everything in Measurement & Automation Expoler (or MAX). MAX will not to measure frequencies for you, but you will be able to at least count pulses. You can do this buy opening up a DAQmx Test Panel for your board and selecting the Counter Tab.

Regards,
Anuj D.

[FRG]

I have just been having similar problems.
My error was that I was setting the DIO port to be an output port.
One of the port lines is connected to the counter for use when externally controlling up/down counting. This line needs to be tri-stated.
This could be something to check.

[Biobartman]

The problem ended up being the shape of the signal. I squared up the signal using a schmitt trigger and everything worked great after that.

Thanks for your input

MAX was a great tool. I just wish you could select the PFI line directly from MAX.

Biobartman