Hi there,

I have following problem with one of my G320 drives.
Everything was working well on the prototype of my 3D milling
machine.
I set up current limit, gain and damping and my 3 servos were running
smoothly. The only thing I had to do with the all the axis is to
short the error/reset pin to +5VDC each time after switching on the
power supply, but I guess this is normal. After this reset, all
G320's stayed OK during the testing (until the next power cycle).

As this a machine under construction I didn't pay to much attention
on the wiring. During testing one of the wires at the motor end of the Y axis became loose and touched the motor chassis. I saw a few sparks and the
switch mode power supply shut down, but no smoke... The 4 amp fuse in
the supply to the G320 didn't blow.

After repairing the loose wire I tried again, but now this G320
stays in fault condition, even after shorting the error/reset pin5 to 5VDC
for a long time. I tried the motor/encoder on a different G320 and
it is working fine. From the block schematic in the manual, I see the
the flip flop for the fault condition is reset by shorting pin5 to +5VDC
and is set either by the over current (safety) limit or by the position
error signal in the loop ( if exceeding 128 bits). Since the
counters are reset when pin5 is connected to +5VDC, by definition, the
position error is zero. The voltage between testpoint and GND is 5V, so this means that the position error is zero.
So my guess is the the G320 detects a short somewhere. Even when
disconnecting the motor, I can't reset the fault light. (I can with a different controller) I checked the mosfets on the faulty drive and they seem OK (at least they are not short circuit). The current sense resistor is very low
resisance, so that seems OK as well. 5 volts is present and fault
light stays on all the time.
Is there anything else that would prevent the flipflop to reset?
Without schematic diagrams it's not easy to fault find these tiny
little things.

Of course, when the motor gets disconnected and the wire sparks to ground, a high voltage can be generated (the motor coil has a lot of energy when running). An overvoltage could destroy some of the electronics.

I hope this G320 one is not for the bin.
Anyone has a clue what I can do next?


Thanks,

Luc