Motors will not engage / re-engage
Symptoms
Either the servo drives will not engage when the controller has been sent the ‘engage' command, or the drives have disengaged automatically
and will not re-engage.
Possible causes (or reported causes)
After switch on, before the system is allowed to engage, it must be configured for motion (i.e. the machine, servo and move parameters must
be sent to the controller).
Any of the “fatal faults” will prevent the system from engaging, in addition the following will disengage the servo motors.
A reported failure from a servo power amplifier (amplifier feedback signal).
The absence of the feedback signal from the motor contactor.
The following list can also inhibit drive engagement or re-engagement.
The probe being deflected
Any outer limit switch being operated, or a soft limit exceeded.
An active PICS STOP signal.
Specifying the wrong probe type in the machine configuration, since open-circuit analogue probe inputs may eventually drift to an
apparently ‘deflected' value.
Tests / cures
Check each of the above signals using the status flags returned to the host PC, and / or by confirming the values of the actual signals reaching
the controller.
UCCassist-2 can be used for further help with this by displaying the system status, the status bytes and the PICS signals.
The amplifier and motor contactor feedback signals can also be examined using the ‘input signals' window.
A PICS STOP signal may originate from an external accessory such as a probe head controller. If the external device is a Renishaw interface it
will indicate it is asserting the PICS STOP by illuminating its own stop led but it may be necessary to remove the PICS connections to
peripherals one by one to establish which one is responsible.
Remember, a PICS accessory may produce a STOP signal. Renicis can be used to find the condition causing this, which should then be
removed.
UCC2 and UCC2-2 installation guide
www.renishaw.com
Issued 07 2021
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