Is there any way to get a 'steps per readout' on my Mach3 turn screen
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Not directly. Your steps per are a calculated value for angular moves based on your system.
Actual pulses sent for a move can be measured if you have the right electronic equipment. My friend used one
which had 6 channels and would show actual pulses sent to some accuracy of 10 parts per million.
Just saying that there is a calculated value and a measured value and also there can be a difference depending on where you are measuring the pulses.
You could add a DRO on the screen, the basis of which would be a calculated pulse value and that value would show in the DRO. Not sure if it would be worth it since you could always just use the calculator. Also can use the axis calibration feature to compared a move.
FWIW,
RICH