Dg4s160-35 limit override

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Dg4s160-35 limit override

Postby Pinko12007 » Tue Dec 05, 2017 8:11 pm

When feeding a dg4s160-35 goes into alarm limit override and even intervening on the programmed value the drive is not unlocked. How can I intervene at the motor and encoder level to unlock the drive? Thank you
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Re: Dg4s160-35 limit override

Postby cncdrive » Tue Dec 05, 2017 10:58 pm

A limit override means that the servo error ran too high, the servo error is the step/dir signals counts summary minus the encoder counts summary, in other words it is the position error measured from the commaneded postion.
The limit override is a serious error, because it means your motor could not follow the position where you commanded the axis, the servo error ran higher than the max.error parameter you setup in the drive.
If the limit override happens then you can reset the drive via the reset line or you can unpower the drive's digital part and power it up again.
The reset procedure is described in the DG4S manual, basicly you can pull the reset line low and then release the line and so the drive will reset.
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Re: Dg4s160-35 limit override

Postby Pinko12007 » Wed Dec 13, 2017 8:09 pm

My problem is that this alarm appears when the drive is turned on, before commanding any movement.
If the power is turned off, the drive does not go into alarm
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Re: Dg4s160-35 limit override

Postby cncdrive » Wed Dec 13, 2017 9:43 pm

If power is turned off then ofcourse the drive can't go to alarm, because it is then unpowered.
If the drive goes into a limit override fault even with the motor moving means that the encoder or the controller which sends the step/dir signals sends unwanted signals.
It is possible that the encoder is faulty or the card which sends the step/dir signals has an issue.

Or if the motor moves and so the drive goes into fault as soon as you powering the drive up, then the encoder is connected up in reverse, the A channel is mixed up with the B channel, so the PID controller moves the motor not to, but from the setpoint until the servo position error reaches the set maximum and the drive faults. If this is the case then exchange the encoder A with B connection to the drive or exchange the motor arm1 with arm2 connection. Exchanging one of them will do the same, both reverse the count direction.

It is also possible that the set servo error in the PID tuning was set very low, e.g. 1-2 encoder counts and so when the drive powers up it basicly immediately faults as soon as it starts running the loop and moving the motor a littlebit on startup. So, also check what the max. error parameter value is in the PID tuning.
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