How to connect and scale a frequency input to measure RPM from an encoder
To measure RPM using an encoder, you really need to just measure frequency of either A or B.
If direction of the shaft is not important, you do not need to setup the channel as a counter/quadrature.
To measure RPM, setup the digital input channel on the module as a standard frequency measurement
Either A or B is connected to DIn.
Once you obtain a frequency measurement, you can convert to RPM. Knowing that the maximum RPM of the Model 725 is 8000 RPM:
(8000 rev/min) x (1 min/60 sec) x (360 pulses/rev) = 48000 pulses/sec = 48 kHz
Go to the scaling section. Type in manually "RPM" for the unit.
Point 1: 0 Hz to 0 RPM
Point 2: 48000 Hz to 8000 RPM
Enter a time base. If it is a high frequency, you do not need much time to count the ramps, but if the frequency gets too low, you will need more time to recognize enough ramps to obtain an accurate result.
If you want to use the sensor as an encoder, you will only be measuring counts (pulses). To be able to convert the counts to RPM, you have to compare the number of counts measured in a known time interval.
The equation would be:
You know the Pulses Per Revolution = 360 or 720 (depending on which encoder you are using).
The counter/quadrature/4-wire variable of the module will give you counts.