modiconguy
Member
A bit of background here:
We use an incremental encoder with a counting module in our PLC configuration. Using dual phase / quadrature counting, we know the position of the motor (which makes several turns) and we can differentiate to find the velocity. We would like to control the velocity of the motor to get the predictable speeds under varying load.
Given the maximum frequency of the counting module, and the maximum rotational velocity of the motor, I think we could clearly identify the maximum encoder resolution that we could support. It should be less than the max frequency (Hz) of the counter divided by the max revolutions/second of the motor, right?
Secondly, given an encoder resolution and a PLC scan time, what's the slowest practical revolutions/second we can expect to get reliable PID control of slow velocities? I'm guessing it would be a rule of thumb like "the time between pulses should be less than 10x the scan time" or similar.
We use an incremental encoder with a counting module in our PLC configuration. Using dual phase / quadrature counting, we know the position of the motor (which makes several turns) and we can differentiate to find the velocity. We would like to control the velocity of the motor to get the predictable speeds under varying load.
Given the maximum frequency of the counting module, and the maximum rotational velocity of the motor, I think we could clearly identify the maximum encoder resolution that we could support. It should be less than the max frequency (Hz) of the counter divided by the max revolutions/second of the motor, right?
Secondly, given an encoder resolution and a PLC scan time, what's the slowest practical revolutions/second we can expect to get reliable PID control of slow velocities? I'm guessing it would be a rule of thumb like "the time between pulses should be less than 10x the scan time" or similar.