FANUC Alarm SRVO-021 — SERVO SRDY off (Group:%d Axis:%d)
FANUC SRVO-021 (“SERVO SRDY off (Group:%d Axis:%d)”): The HRDY signal is on and the SRDY signal is off, although there is no other cause for an alarm. First check: 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. Likely part: Servo amplifier (Servo amplifier) +4 more.
Updated 2026-08-29 · LogrobotLM reference
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 · Remède
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.
Part to check / replace · Pièce à contrôler / remplacer
FANUC SRVO-021 points to the hardware below — start here before ordering. · SRVO-021 met en cause l'organe ci-dessous : commencez par là.
- Servo amplifierServo amplifier· Amplificateur servo
- Axis control cardAxis control card· Carte de commande d'axes
- Main boardMain CPU board· Carte principale (main board)
- E-stop unitE-stop unit· Unité d'arrêt d'urgence (E-stop)
- Panel boardOperator panel board· Carte panneau opérateur
Tap a part for every code that points to it — and verify the exact variant for your controller before ordering. · Touchez une pièce pour tous les codes qui la citent ; vérifiez la variante exacte avant commande.
Frequently asked · Questions fréquentes
- What does FANUC alarm SRVO-021 mean?
- FANUC SRVO-021 (“SERVO SRDY off (Group:%d Axis:%d)”): 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…
- How do you troubleshoot FANUC alarm SRVO-021?
- 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,…
- Which part is involved in FANUC SRVO-021?
- SRVO-021 points to Servo amplifier (Servo amplifier), Axis control card (Axis control card), Main board (Main CPU board), E-stop unit (E-stop unit), Panel board (Operator panel board). Confirm the real cause against the robot backup before replacing a part.
Related codes / Codes liés
Same hardware involved / Même matériel en cause
Indicative field information — the robot manufacturer's manual and safety procedures always prevail. Never bypass a safety device; apply lockout/tagout (LOTO) before any physical intervention. · Informations indicatives issues du terrain — le manuel du constructeur et ses procédures de sécurité font foi. Ne shuntez jamais un organe de sécurité ; consignez (LOTO) avant toute intervention physique. How this reference is built →