FANUC Alarm SRVO-021 — SERVO SRDY off

Description

The HRDY signal is on and the SRDY signal is off, although there is no other cause for an alarm. (HRDY is a signal with which the main board directs the servo system whether to turn on or off the servo amplifier magnetic contactor. SRDY is a signal with which the servo system informs the main board whether the magnetic contactor is turned on.)

Remedy

1. Make sure that connectors CP2 and CRM73 of the E-stop unit and CNMC2 and CNMC3 of the E-stop unit are connected tightly. 2. Check whether an outage has occurred on an emergency stop line (teach pendant EMERGENCY STOP, teach pendant enable/disable switch, teach pendant DEADMAN switch, operator panel EMERGENCY STOP, external emergency stop input, fence input, servo-off input, or door switch). This alarm occurs if the software cannot detect the alarm cause because of a short signal break and because the magnetic contactor is off. 3. Replace the servo amplifier. 4. Replace the E-stop unit. 5. Replace the cable between the E-stop unit and the panel board. 6. Replace the cable between the E-stop unit and the servo amplifier. 7. Verify that the battery is securely connected to the Main CPU board before removing the board. Replace the axis control card on the Main CPU board.

Field diagnosis

The "ready" signal of the designated axis amplifier dropped while the power-on command is maintained: the amplifier contactor does not hold, or the axis configuration designates an amplifier that does not exist.

What to check

• First read the other alarms from the same second and deal with them.
• If the code follows the addition of an axis or a configuration change, check the hardware axis number and the amplifier number and type.
• Otherwise amplifier, then emergency stop unit.
• Note: Almost always a symptom of another code: do not diagnose it on its own.

Related codes

Same hardware involved