May 28, 2025
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If you're working with Fanuc Power Mate controllers, encountering alarms is part of the journey. Whether you're using Power Mate Model D, Model H, or i–D series, alarms help pinpoint issues and get your machine back on track. But understanding what they actually mean—and how to fix them—is key to minimizing downtime.
In this guide, we’ve compiled the most common Fanuc Power Mate alarms, including their meanings and recommended actions. Whether you’re a technician, engineer, or maintenance operator, this list will help you decode those flashing numbers on your CNC screen.
Fanuc Power Mate alarms are system-generated error codes that indicate hardware, software, or communication problems within the controller or related components. They’re triggered when something goes outside normal operating parameters—think servo overloads, encoder issues, I/O faults, and more.
Fanuc alarms are typically categorized as:
Servo Alarms
System Alarms
Spindle Alarms
Input/Output (I/O) Alarms
Operator or Manual Errors
Each type has a code and message displayed on the operator panel, making it easier to identify and fix the issue.
Below is a list of common alarms for Fanuc Power Mate D, H, and i-D series controllers:
| Alarm Code | Description | Possible Causes | Recommended Action |
|---|---|---|---|
| 000 | Watchdog Timer Alarm | Internal system error | Cycle power. If issue persists, check PCB or replace CPU |
| 001 | ROM Checksum Error | Corrupt ROM or firmware | Reload firmware or replace main board |
| 003 | SRAM Parity Error | SRAM error or data corruption | Re-initialize parameters or replace SRAM board |
| 004 | CPU Error | Internal processor fault | Replace CPU module |
| 008 | Format Error | Incompatible parameter format | Reload parameters or check configuration settings |
| Alarm Code | Description | Possible Causes | Recommended Action |
|---|---|---|---|
| 400 | Servo Alarm – Excess Error | Encoder misalignment, mechanical overload | Inspect motor coupling, check encoder, realign axis |
| 401 | Servo Error Detection | Abnormal motor feedback | Reset alarm and verify feedback loop |
| 402 | Overcurrent | Short circuit or servo drive fault | Inspect wiring, replace servo amplifier if needed |
| 403 | Overload Alarm | Excessive load or resistance | Check mechanical binding or axis drag |
| 409 | Velocity Control Alarm | Tacho or feedback signal error | Check motor connections or replace tacho-generator |
| Alarm Code | Description | Possible Causes | Recommended Action |
|---|---|---|---|
| 600 | Spindle Drive Error | Inverter fault, motor overheating | Inspect cooling, check spindle amplifier |
| 602 | Speed Reference Error | Encoder or command signal missing | Inspect encoder wiring or replace sensor |
| Alarm Code | Description | Possible Causes | Recommended Action |
|---|---|---|---|
| 700 | I/O Link Error | Communication fault between CNC and I/O | Check fiber optic or serial cable, reboot system |
| 701 | I/O PCB Error | Internal I/O board fault | Inspect I/O PCB or replace |
| 710 | Ladder Sequence Error | Improper I/O program logic | Check PMC ladder program |
| Alarm Code | Description | Possible Causes | Recommended Action |
|---|---|---|---|
| 900 | Emergency Stop | E-stop button pressed or external fault | Release E-stop, inspect for faults |
| 903 | Door Open | Door interlock open | Close door properly and reset |
| 905 | Machine Lock | M-code or parameter lock active | Disable machine lock if needed |
To view and reset alarms on Fanuc Power Mate:
Check the Operator Display: Alarms appear as numerical codes. Use the system manual to look up meanings.
Use the Diagnosis Page: Navigate to the [DIAGNOSIS] or [SYSTEM → ALARM] screen.
Power Cycle the Controller: For minor issues, switching off and on might reset the alarm.
