Fanuc Wn57 Override Function Is Active -
After performing a Block Search (mid-program start), the operator may not complete the "distance-to-go" cancellation. The controller remains in an “Override” state (a type of position deviation allowance) until the cycle start is pressed again. Attempting to edit or reset the sequence prematurely triggers WN57.
⚠️ Only do this if you fully understand safety risks.
Safer approach:
Set a default program header to force overrides to 100% at start:
G10.6 P0;
G10.9 P0;
M48; (if builder uses M48/M49 for override enable)
You will typically see the message "WN57 OVERRIDE FUNCTION IS ACTIVE" under the following conditions:
| Your goal | What to do | |-----------|-------------| | Just remove WN57 | Set rapid/feed override to 100%, dry run OFF, press RESET | | Run with override <100% | Ignore the warning if machine allows | | Machine refuses to run | Call machine tool builder – they set the logic | | You want to disable it | Check PMC ladder or FANUC parameter 3001#5 (OVW) |
If the machine is cutting correctly and no other alarms exist, WN57 is informational, not critical.
The message "WN57 OVERRIDE FUNCTION IS ACTIVE" is a specific Programmable Machine Control (PMC) alarm found on Fanuc systems, indicating that the system's "Override Function" (倍率功能) has been enabled.
This is not typically a mechanical failure but a status alert informing you that the PMC is currently in a debugging or forced state. Core Meaning of WN57
The WN57 alarm appears when the PMC Override feature is active. This tool is primarily used by developers or maintenance technicians during the debugging process to:
Force PMC signals to specific states regardless of physical I/O conditions.
Test logic within the PMC program without needing the actual machine hardware to be in a specific position. fanuc wn57 override function is active
Bypass certain interlocks temporarily to verify program flow. Why It Needs to Be Deactivated
While useful for testing, this function should be disabled once debugging is complete. If left active, it can:
Prevent normal operation: Forced signals may prevent the PMC from responding to real sensors or operator inputs.
Create safety risks: Crucial safety interlocks might be bypassed or ignored by the forced logic. How to Resolve the Alarm
To clear the WN57 message, you must disable the override function through the system parameters or the PMC maintenance screen: Via PMC Parameters: Navigate to the PMC Parameter Setting screen. Locate the Override Function (倍率功能) option. Change the setting from "Effective/Yes" to "No". Via Keep Relays (K-Addresses):
The override function is directly linked to the system address K906.0.
Setting K906.0 to 0 will immediately deactivate the function and clear the WN57 alarm after a system restart.
Are you currently debugging a new PMC ladder, or did this alarm appear unexpectedly on a machine that was previously running?
What it is:
The WN57 alarm (or status message) on a FANUC CNC control indicates that an override function is currently enabled – typically a rapid traverse override, feed rate override, or a dry run override. Unlike many alarms, WN57 is generally an informational message, not a critical error. The machine will continue to run, but with altered motion parameters.
When it appears:
Key implications:
Useful tips for operators:
Pros of having this message:
Cons / annoyances:
Final verdict:
A useful safety reminder, not a problem. Treat it as a “heads-up” that the machine is not running exactly as programmed. Always check it before running production.
If you need help disabling a specific override or understanding a custom ladder message related to WN57, let me know your FANUC control model (e.g., 0i-MF, 31i, 18i).
The WN57 OVERRIDE FUNCTION IS ACTIVE message is a specific PMC (Programmable Machine Control) alarm found on FANUC CNC systems . It indicates that the Override Function—a debugging tool used to manually force PMC signals—is currently enabled .
While this function is active, the PMC may not operate according to its standard programmed logic because signals are being "overridden" for testing purposes. It is generally recommended to disable this function once debugging is complete to ensure normal machine operation . How to Resolve WN57
You can deactivate this function using one of the following methods: Via PMC Parameters: Navigate to the PMC Parameter setting screen. Locate the Override Function (倍率功能) option.
Move the cursor to the "Valid" (有效) setting and change it to "No" or "Invalid" . Using Keep Relays: After performing a Block Search (mid-program start), the
Directly change the keep relay address K906.0 to 0. Setting this bit to 0 disables the override function and should clear the WN57 alarm after a system restart .
Note: Since WN (Warning) alarms are often informational, the machine might still run, but specific safety or logic interlocks handled by the PMC could be bypassed by the active override. 【报警】FANUC PMC"WN57 OVERRIDE FUNCTION IS ACTIVE"
The WN57 (also written as W057) is a status message on FANUC Robodrill and CNC systems indicating that the Override Function is currently active.
While it may appear as a warning, this "Override Function" is a helpful feature designed for safety and process verification during machine setup or program testing. Key Benefits of the Override Function
Safe Program Verification: It allows you to run a program at a reduced speed—often significantly lower than the programmed feedrate—to ensure there are no collisions or errors before running at full production speed.
Variable Speed Control: You can manually adjust the feedrate (Feedrate Override) or rapid traverse (Rapid Override) percentages using the dials or buttons on the control panel.
Tool Protection: By slowing down the motion during the first run of a new tool or part, you can stop the machine quickly if the tool path looks incorrect. Why You See the WN57 Message
The message typically appears when the system detects that the Override Select or a related custom PMC (Programmable Machine Control) function has been engaged.
Diagnostic Tip: If you want to disable this feature to run at 100% speed, ensure all override dials are set to 100% and any "Dry Run" or "Override" toggle switches are turned off.
System Variables: In some cases, advanced users can control or disable these overrides through system variables like #3004 or $GENOV_ENB to prevent accidental speed changes during production. ⚠️ Only do this if you fully understand safety risks
If you'd like to know the specific parameter number to disable this warning or how to lock the override at 100% for production, just let me know! Four Ways to Control FANUC Robots' Speed Override
Before you panic and reboot the entire machine (which you should avoid unless necessary), follow this systematic checklist.