liminfoFANUC Alarm Code Reference
FANUC CNC alarm and error code reference with causes and solutions
About FANUC Alarm Code Reference
The FANUC Alarm Code Reference is a comprehensive, searchable database of FANUC CNC alarm codes with detailed causes and step-by-step troubleshooting solutions. It covers CNC System alarms (PS0001 parity error, PS0010 invalid G-code, PS0011 feed rate missing, PS0030 illegal P/Q, PS0077 subprogram nesting), Servo alarms (SV0001 excess error, SV0003 EMG, SV0005 encoder disconnect, SV0006 FSSB error, SV0401 VRDY off), Spindle alarms (SP0001 overload, SP0002 overheat, SP0012 speed deviation, SP0015 encoder error, SP0029 orientation failure), PMC/PLC alarms (PC0000 watchdog, PC0201 program not found, PC0300 I/O error, PC0400 battery), and Operation alarms (OT0500-0505 over-travel, OH0700 CNC overheat, SR0085/0086 SRT communication).
Essential for CNC operators, maintenance engineers, machine tool technicians, and factory automation specialists working with FANUC Series 0i-TF, 30i-B, 31i-B, and related controllers. Each alarm entry includes the alarm code, description, root cause analysis, and a prioritized list of troubleshooting steps covering electrical, mechanical, and parameter checks.
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Key Features
- CNC System (PS) alarms: PS0001 parity error, PS0006 missing EOB, PS0010 invalid G-code, PS0011 feed rate, PS0030 P/Q value, PS0077 nesting depth
- Servo (SV) alarms: SV0001/0002 excess error, SV0003 EMG, SV0005 encoder cable, SV0006 FSSB, SV0007 speed deviation, SV0011 overheat, SV0401 VRDY off
- Spindle (SP) alarms: SP0001 overload, SP0002 overheat, SP0003 fuse, SP0009 CSS link, SP0012 speed deviation, SP0015 encoder, SP0017 stall, SP0029 orientation
- PMC/PLC (PC) alarms: PC0000 watchdog, PC0001/0002 parity/RAM error, PC0201 program not found, PC0300/0302 I/O communication, PC0400 battery low
- Over-travel (OT) alarms for +/-X, Y, Z axes with hardware limit switch troubleshooting steps
- Overheat (OH) and fan failure alarms with cooling system diagnostic procedures
- SRT (SR) alarms covering FSSB optical cable and CNC-servo real-time communication errors
- Applicable to FANUC Series 0i-TF, 0i-TF Plus, 30i-B, 31i-B, 31i-B5, and 32i-B controllers
Frequently Asked Questions
What does FANUC alarm SV0001 mean and how do I fix it?
FANUC SV0001 indicates excessive position deviation (droop) during axis movement. The servo motor position error exceeds the parameter-set threshold. To fix: 1) Check for excessive mechanical load on the ball screw and guide lubrication. 2) Adjust servo gain parameters (parameter 1825). 3) Reduce feed rate and test. 4) Inspect the servo motor and amplifier for faults. 5) Check encoder cable connections for contact issues. If the alarm occurs intermittently, suspect electrical noise or cable degradation.
How do I troubleshoot FANUC servo alarm SV0005 (encoder disconnect)?
SV0005 indicates communication loss between the servo motor encoder (pulse coder) and the CNC. Steps: 1) Disconnect and firmly reconnect encoder cable connectors at both ends. 2) Inspect the cable for physical damage, broken wires, or crushed insulation. 3) Measure encoder resistance to test for internal failure. 4) Check connector pins on the servo amplifier side for corrosion. 5) Reroute the cable away from power lines to reduce electromagnetic interference. If the alarm persists after cable replacement, the encoder itself may need replacement.
What causes FANUC spindle alarm SP0001 (overload)?
SP0001 triggers when spindle motor current exceeds the overload protection threshold. Common causes: 1) Aggressive cutting conditions (high feed rate or depth of cut). 2) Worn cutting tools increasing cutting forces. 3) Deteriorated spindle bearings causing mechanical drag. 4) Spindle amplifier current limit parameters set too low. 5) Cooling system failure causing thermal derating. Reduce cutting parameters first, check tool condition, then inspect spindle bearings and the amplifier cooling system.
How do I clear FANUC over-travel alarm OT0500-OT0505?
OT alarms (0500-0505) indicate a hardware limit switch has been triggered on the +/- X, Y, or Z axis. To clear: 1) In JOG mode, manually move the axis in the opposite direction (e.g., -X for OT0500). 2) Check hardware limit switch position and proper operation. 3) Verify work coordinate system (G54, etc.) settings have not shifted. 4) Review the NC program for travel range errors. 5) Check soft limit parameters. For Z-axis alarms, also verify tool length compensation (H values) and safety height (R-point) settings.
What does FANUC PMC alarm PC0201 mean?
PC0201 indicates no sequence (ladder) program is stored in the PMC. This typically occurs after PMC board replacement, battery depletion causing data loss, or failed program transfer. To resolve: 1) Transfer the PMC ladder program to the CNC using FANUC LADDER III software. 2) Verify the program is written to FLASH ROM (not just RAM). 3) If the PMC board was replaced, reload the program from backup. 4) Check the backup battery voltage and replace if depleted. 5) Confirm the program transfer completed without errors.
How do I diagnose FANUC SV0006 FSSB communication error?
SV0006 indicates an optical communication error on the FSSB (FANUC Serial Servo Bus) between the CNC and servo amplifier. Steps: 1) Check FSSB optical cable connections at both CNC and amplifier ends. 2) Clean optical cable end faces with lint-free cloth if contaminated. 3) Inspect the servo amplifier slot and FSSB board for proper seating. 4) Verify the CNC mainboard FSSB port. 5) Check axis configuration parameter 1023 for correct settings. Damaged or excessively bent optical cables are the most common cause.
What is FANUC alarm SV0401 (VRDY off) and how do I fix it?
SV0401 means the servo amplifier is not returning the VRDY (ready) signal to the CNC. This prevents axis motion. Troubleshooting: 1) Verify both main power and control power are supplied to the servo amplifier. 2) Check servo amplifier LED status for error codes. 3) Inspect internal fuses in the amplifier. 4) Check the FSSB/signal cable between CNC and servo amplifier. 5) Verify amplifier parameter settings (axis number assignment). 6) Try swapping with another axis amplifier to isolate whether the amplifier or wiring is at fault.
How do I fix FANUC CNC overheat alarm OH0700?
OH0700 indicates the CNC control unit internal temperature exceeds the safe operating limit. Resolution: 1) Check that control cabinet cooling fans are running. 2) Verify air conditioner or heat exchanger is functioning properly. 3) Clean control cabinet air filters to remove dust blocking airflow. 4) Ensure cabinet door seals are intact (no air leaks). 5) Confirm ambient temperature is within 0-45 degrees Celsius. 6) Inspect heat sinks on the mainboard for dust accumulation. Fan failure alarm OH0701 often precedes OH0700 and should be addressed immediately by replacing the failed fan with genuine FANUC parts.