Fanuc alarm: 404 - SERVO ALARM: n-th AXIS VRDY ON

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bradders
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Fanuc alarm: 404 - SERVO ALARM: n-th AXIS VRDY ON

Post by bradders » Wed 07 Sep , 2011 14:29 pm

CNC Description: Even though the n-th axis (axis 1-8) READY signal (MCON) went off, the servo amplifier READY signal (DRDY) is still on. Or, when the power was turned on, DRDY went on even though MCON was off. Check that the axis card and servo amplifierr are connected.
Fanuc alarm: 404 - SERVO ALARM: n-th AXIS VRDY ON

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Re: Fanuc alarm: 404 - SERVO ALARM: n-th AXIS VRDY ON

Post by bradders » Wed 07 Sep , 2011 15:10 pm

This might be relevant for problem solving.....
The PRDY signal is generated on the mother board, and that is supposed to pull in the MCC relays on the servo drives. The MCC contactors have a set of small auxillary contacts that close when the MCC pulls in, and that sends the VRDY (Velocity units ready) signals back to the CNCs mother board.

The PRDY signal comes from a set of 3 small IC reed relays on the mother board, and one relay for each axis will pull in as soon as the control is ready to power up the servos. Each PRDY signal goes to one of the servo boards, where it powers a solid-state relay, which pulls in the MCC contactor (if the servo is OK). Once the MCC pulls in, the VRDY is returned to the mother board and goes to a 24v receiver hybrid IC.

The timing here is important. The control does not want to see the VRDY from the servos until AFTER it outputs the PRDY signals. If one of the MCC contactors is stuck, or if a PRDY relay on the mother board is stuck, then the timing is upset.

If the MCC contactors do not click in (you should definitely hear them), then the problem is that one of the VRDY signals is being returned even though the contactor is not actuated. Check those contacts on the side of each MCC relay to be sure one of them isn't stuck. Also verify that there are no "jumpers" installed. Sometimes service engineers will jumper out the PRDY to test a servo. The Honda connectors on each servo board must be plugged in and tight. Those 3 cables all come together to a 50-pin Honda plug on the mother board, which must also be tight.

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Re: Fanuc alarm: 404 - SERVO ALARM: n-th AXIS VRDY ON

Post by bradders » Wed 07 Sep , 2011 15:17 pm

ALARM 404 AND 405
(*DRDY SIGNAL
TURNED ON)

Alarm 404 DRDY signal is turned on before MCON signal is turned on. Or DRDY
is not turned off after MCON signal is turned off.
[Causes]
1 Servo amplifier is faulty.
2 Between servo amplifier and axis card is faulty.
3 Axis card is faulty

Alarm 405 (Reference
positin return is
abnormal) The grid signal is not turned on when the automatic reference position
return by G28 is completed.
[Causes]
Axis card is faulty.

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