Before you panic and reboot the entire machine (which you should avoid unless necessary), follow this systematic checklist.
The WN57 message indicates that an Override Function (such as Feedrate Override, Spindle Override, or Rapid Traverse Override) is currently active while a specific prohibited operation (like a threading cycle or rigid tapping) is being attempted.
In simpler terms: The CNC is telling you, “I cannot run this cycle because someone has turned a knob (override) that I am not allowed to ignore right now.”
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" is a FANUC PMC (Programmable Machine Control) alarm message indicating that the system's "Override" or "Force" function is currently enabled.
While the term "override" usually refers to physical knobs for feed or speed on a CNC panel, this specific WN57 message refers to a PMC software debugging tool. What WN57 Means
In FANUC systems, the PMC Override function allows a technician or programmer to manually force specific signals (inputs or outputs) to a desired state, regardless of the actual logic or physical sensor status.
Purpose: It is primarily used during machine commissioning or troubleshooting to simulate signals or bypass certain interlocks to test ladder logic.
The Message: WN57 is a warning rather than a critical system fault. It informs the operator that the machine logic is not running in its standard state because at least one signal is being artificially held or "overridden." Why It Stays Active
The message persists as a safety precaution. If this function is left active after maintenance: The machine may behave unpredictably. Safety interlocks might be bypassed.
Standard PMC ladder logic operations may be ignored in favor of the manual "force." How to Resolve the WN57 Warning fanuc wn57 override function is active
To clear the WN57 message and return the PMC to normal operation, you must disable the override status in the system settings:
Locate PMC Settings: Navigate to the PMC or SYSTEM menu on your controller.
Access PMC Parameters: Find the [PMC Parameter] or [PMC Config] screen.
Disable Override: Look for an option labeled Override or Override Effective. Use the cursor to change this setting from "Yes" to "No".
Check Keep Relays (K-Addresses): In many systems, this function is tied to a specific keep relay. Setting K906.0 to "0" will often immediately deactivate the override function and clear the WN57 message.
Caution: Before turning off the override, ensure that any forced signals were not masking a physical fault or sensor failure, as the machine will immediately return to following the actual physical inputs.
The Fanuc message "WN57 OVERRIDE FUNCTION IS ACTIVE" is a PMC (Programmable Machine Control) status message indicating that the machine's signal override feature is currently enabled. This function is primarily used as a debugging tool
by technicians to manually force PMC signals (I/O) during system setup or troubleshooting. While active, it can interfere with the normal logic of the ladder program, which may cause unexpected machine behavior. How to Disable the Message
If the machine has finished being serviced or debugged, you should disable this function to return to standard operation. Use one of the following methods: Via PMC Parameters: Navigate to the PMC Parameter setting screen. Locate the Override Function (often listed as "倍率功能" or "Override Mode"). Move the cursor to the "Valid" setting and change it to Via Keep Relays (K-Address): Change the value of system keep relay Why This Message Appears Active Debugging:
A technician may have left the signal override active after checking the electrical system or I/O signals. Safety Bypass:
In some cases, overrides are used temporarily to bypass interlocks during maintenance (e.g., door interlocks). System Restart Required:
On certain models like the Fanuc 30i/31i/32i, excessive override paths (more than three) may trigger related alarms (like ER47) that require a full CNC restart to clear after settings are adjusted. ladder logic addresses
for a specific Robodrill model to verify which signals are currently being forced?
Understanding the FANUC WN57 Override Function: A Comprehensive Guide
In the world of CNC machining, FANUC is a renowned name that has been synonymous with precision, reliability, and innovation. One of the key features that set FANUC apart from its competitors is its advanced override function, which allows users to adjust the machining process in real-time. In this article, we will focus on the FANUC WN57 override function, exploring its capabilities, benefits, and applications.
What is the FANUC WN57 Override Function?
The FANUC WN57 override function is a feature available on certain FANUC CNC control systems, particularly on the WN57 model. This function allows users to temporarily adjust the feed rate, spindle speed, or other machining parameters during a running program. The override function is designed to provide greater flexibility and control over the machining process, enabling users to make adjustments on the fly. Before you panic and reboot the entire machine
How Does the FANUC WN57 Override Function Work?
When the FANUC WN57 override function is active, users can modify the machining parameters using a dedicated override switch or button on the CNC control panel. This allows them to increase or decrease the feed rate, spindle speed, or other parameters in real-time, without having to stop the machine or modify the program. The override function can be used to:
Benefits of the FANUC WN57 Override Function
The FANUC WN57 override function offers several benefits to CNC machinists and manufacturers, including:
Applications of the FANUC WN57 Override Function
The FANUC WN57 override function is commonly used in various CNC machining applications, including:
Best Practices for Using the FANUC WN57 Override Function
To maximize the benefits of the FANUC WN57 override function, users should follow best practices, including:
Troubleshooting Common Issues with the FANUC WN57 Override Function
While the FANUC WN57 override function is designed to be reliable and user-friendly, issues can arise. Common problems and their solutions include:
Conclusion
The FANUC WN57 override function is a powerful tool that offers CNC machinists and manufacturers greater flexibility and control over the machining process. By understanding how to use this function effectively, users can optimize machining conditions, improve productivity, and reduce costs. Whether you're a seasoned CNC machinist or new to the world of CNC machining, the FANUC WN57 override function is an essential feature to master.
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. Key implications:
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?
Title: Understanding FANUC WN57: "Override Function is Active"
Body:
If you are running a FANUC-controlled CNC machine and have encountered the WN57 alarm or status message stating "Override Function is Active," don’t panic.
This is not a critical machine failure, but rather a protective notification. Here is a breakdown of what it means, why it appears, and how to resolve it.
If step 1–3 fail, the machine builder’s PLC is holding WN57 active.
WN57 on FANUC CNC controls indicates that the machine is running with an active feed override or rapid override function tied to a safety or watchdog feature that modulates axis motion. It’s commonly seen as a displayed override status (often in the MPG/MDI or alarm/message area) when the control has detected a condition where commanded motion has been limited or overridden by the system. The exact behavior and causes vary by FANUC series and machine OEM implementation.
✅ Rapid traverse override set to 100% when parameter has flagged that as “override active”
✅ Feed override knob set above 100% (if parameter enabled)
✅ Manual handle override (jog/handle multiplier in effect)
✅ Programmed override via PMC or G-code (e.g., G10.6 or G10.9 on some controls)
✅ Dry run + feed override combination tripping a builder-defined warning
✅ Machine builder’s custom PMC logic activates WN57 when any override ≠ 100%
On newer FANUC i-Series (Series 0i-F, 31i-B5), overrides can be triggered via soft keys: