Fanuc Alarm 0: PLEASE TURN OFF POWER

Fanuc Alarm 0: PLEASE TURN OFF POWER

Fanuc Control Model: Series 16 / 18 / 21, 16i / 18i / 21i, 0i Series

Fanuc Alarm 0 (PLEASE TURN OFF POWER) is a standard notification alarm that occurs when a parameter requiring a power cycle/reboot is modified on the CNC control. Follow this quick guide to safely clear the alarm and apply your parameter changes.

Official Alarm Description

A parameter which requires the power off was input, turn off power.

Common Causes

This alarm is not a hardware fault or G-code error; it is triggered by system configuration updates:

• Modifying Protected Parameters: Changing system settings such as axis configuration, communication settings (RS232/Ethernet), or option parameters.
• PMC Parameter / Data Alterations: Modifying PMC parameters or timers that dictate machine control logic.
• Restoring System Backups: Loading a parameter backup file via SRAM card or memory card that overwrites existing system configurations.

Step-by-Step Troubleshooting & Solution

Follow these steps to clear Alarm 0 and activate your updated parameters:

1. Save/Confirm Parameter Changes: Ensure that you have completed entering the required parameter values in MDI mode or via parameter settings.
2. Turn OFF the Main CNC Power: Switch off the NC power button on the operator panel, then turn off the main breaker switch.
3. Wait for Discharge (5–10 Seconds): Wait a few seconds to allow all internal capacitors and servo drives to fully power down and discharge.
4. Turn Power Back ON: Flip the main breaker switch back on and press the NC Power ON button.
5. Verify Clear Status: The alarm will disappear automatically, and the new parameter settings will take effect.

G-Code / Parameter Example

Modifying Parameter 1001 (Inches/Metric setting) or Axis parameters without cycling power keeps Alarm 0 active on the screen.

Save parameter changes ➔ Turn Main Power OFF ➔ Wait 10 seconds ➔ Turn Main Power ON.

Frequently Asked Questions (FAQs)

Q1: Will pressing the RESET button clear Fanuc Alarm 0?

No. Pressing RESET will not clear Alarm 0 because the controller requires a complete power cycle to load the newly modified parameters into system memory.

Q2: Is Fanuc Alarm 0 harmful to the machine?

Not at all. It is simply a safeguard prompt letting the operator know that a system restart is necessary for changes to take effect.

Have you faced Fanuc Alarm 0 PLEASE TURN OFF POWER on your machine? Share your experience or troubleshooting tips in the comments below to help other CNC operators and programmers clear this error faster!