DMC4183 control. A & B axis set for step motor using MT 2.5,2. Verified all cables, motors and drives are good. Drivers (Sure Step STP-DVR-6575) have self test feature which runs motor back and forth independent of DMC. Both work fine in self test so this eliminates motor cables and motors. Swapped cables from axis to drive and both cables are good. A axis runs fine one direction but when reversed runs faster than programmed speed and not the right distance. Swap cables from A axis to B drive and same results. B axis does not move motor at all. Both axes previously ran servo motors fine. RP command says the steps were given for correct distance. Almost seems like B axis step pulse length is too short for driver to catch? Don't know why A axis would go different speed with different direction.
Galil_RobinR on 06/20/2014 - 08:11
Allen-
I would analyze the stepper output signals Step and Direction. If you have an oscilliscope, disconenct the signals from the driver probe the step + direction outputs, and command the axis to Jog at a specific speed, say 1000 cts/sec. The Step outptu should then show a 1 kHz pulse train. Then JG-1000 and you should see the direciton bit toggle, and the pulse train then slow and then return to a 1 kHz output.
A high-quality DMM likely has a frequency measurement, which can work in a pinch.
If the signals are identical on the controller without connection to the drive, then reconnect to the drive, and re-probe the signals. Andy change in frequency, noise, signal strength? This could be a grounding issue, so make sure you have the single 0V ground reference connection between devices (hub and spoke topology) and ensure that there's no direct short between 0V ground and Earth (Chassis). There should be ~1 Ohm resistance between Earth and GND. Let us know what you find.