Scope and measure phase shift with VI

[NedyalkoPeshev]

I'm looking forward to decision of square signals phase shift measurement. I have 2 phase signals and want to measure phase shift. Here my current solution. It is working, but something not true in sequence. 

[dsb@NI]

Your test is odd in that it changes the frequency (rather than phase) of the delayed signal. Phase/delay is not well defined when looking at signals of different frequencies.

Are you trying to measure delay or phase lag versus frequency? Please define your measurement very explicitly, so we know exactly which problem we are trying to help solve. In that same spirit, what parameters are likely to change (from iteration to iteration and from signal1 to signal2)?

Also, please name things what they are (i.e. 'Period' --> 'Frequency') and save defaults for all controls such that we can run the VI and get signals without first having to decipher code.

[NedyalkoPeshev]

Thanks for fast feedback. The main idea is to start square pulse on the PCB and need to measure time between send the signal and time to delivery signal in the output of the board. That was the reason to compare 2 different signals with my logic. And you are right, maybe is not correct way, because I don't want to change frequency. The main parameter is delay between sending and receive square signal with fixed frequency 2.5kHz. One is give on digital input i mean and other one receive to digital output. Between them is physical channel (PCB). The main parameter is time to delivery.

[dsb@NI]

Synchronize your output and input. Consider a direct wrap back of the do channel to a second digital input channel.

For the delay measurement:
You may be able to do simple edge detection on each signal if the digital sample rate provides sufficient timing accuracy. What is required accuracy?
What magnitude of delay is expected through the PCB signal path? ps, ns, us, ms? 

Recommendation:
Continue evolving your test VI such that it models the real-world signals you measure.

[NedyalkoPeshev]

15ns is time for limit detection. Measurment triggered from first front of signal is good solution. I need to keep PXI card and check my solution? If you have any other ideas i will here to listen you. Thanks again

[NedyalkoPeshev]

Here the situation - PXI card is 6341 and i used counter on mode Two Edge Separation. The frequency of sampling is 10ns. I want to sampling and have result between rise edge of the signals from 2 channels - PFI 8 and PFI 9. I have an error to sampling signal.  

error from program is

Possible reason(s):

Requested values of the Minimum and Maximum properties for the counter channel are not supported for the given type of device.
The values that can be specified for Minimum and Maximum depend on the counter timebase rate.

Property: CI.Min
Corresponding Value: 20.0e-9
Property: CI.Max
Corresponding Value: 42.949673
Property: CI.TwoEdgeSep.Units
Corresponding Value: Seconds
Option: 1
Property: CI.CtrTimebaseRate
Corresponding Value: 100.0e6
Property: CI.Min
Value Must Be Greater Than: 20.0e-9
Property: CI.Max
Value Must Be Less Than: 42.949673