On the Fanuc machines I work with a servo amp fault is very similar to an e-stop condition, only worse. In E-stop power is not removed from the spindle VFD, the servos are disabled (I don't think power is removed from them), and the VFD is sent an e-stop signal and brakes to a stop (actually the VFD has an input that monitors the estop chain). The control and all logic circuits remain fully powered and any axis brakes (such as for the Z axis) are engaged. The effect of a servo fault is essentially the same except the entire machine must be power cycled at the main disconnect to clear the servo fault (simply power cycling at the control is not enough.) Where clearing an e-stop only requires resetting the e-stop and pressing the reset button. Part of why I believe power is not removed from the servos at e-stop is the fact that a tiny power blink on one or all phases will usually cause the servos to set an alarm that requires cycling the power to reset. This is the same for multiple machine models from 3 different large manufacturers.
Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -----Original Message----- From: John Dammeyer <jo...@autoartisans.com> Sent: Wednesday, February 10, 2021 12:09 AM To: 'Enhanced Machine Controller (EMC)' <emc-users@lists.sourceforge.net> Subject: [Emc-users] Dealing with Servo Faults [EXTERNAL EMAIL] Be sure links are safe. Quick question. There's a multi-axis operation in progress. For whatever reason one of the servos throws out a fault and of course stops. Should just the enables to the other servo drives be removed or should power be cut to all drives. I'm not really in favour of dropping out power because that would mean you also lose the ability to easily recover. The other drives and spindle were working so you really just want them stopped and things like coolant shut off. This isn't the same as an ESTOP which does remove all power that could result in motion. Low voltage control and PC are left running. For my PMDX-126 BoB my faults are consolidated and brings the PMDX /FAULT input low. That disables the ChargePump which in turn disables all outputs including the enable to all the drive. And the orange button beside the red one on the user screen goes greyed out. After 4 seconds the /FAULT input is once again brought high (inactive) and now the orange ENABLE button on the screen (or F2) can be clicked which then asserts the ENABLE output to the drives and allows hardware to be controlled again. For my servos taking the ENABLE signal FALSE and then TRUE resets the FAULT condition. If the fault is still there then the /FAULT is brought low again. Etc... What do other systems (including commercial) do when a drive faults on one axis. John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
