The "Override Function" allows an operator or technician to force a signal in the PMC ladder to a specific state (ON or OFF), regardless of the actual logic or physical input. This is useful for:
In automated cells where a FANUC robot interacts with a CNC mill or lathe, the programmable machine control (PMC) manages safety handshakes. If a robot is entering the machine envelope, or if a safety door is open, the PMC may automatically force an override state (e.g., forcing rapid traverse to 0% or 10%) to prevent collisions. WN57 will stay active until the safety conditions are cleared. 3. Macro Program Variables (G-Code Override Suppression)
Allowing the machine to function temporarily while waiting for a replacement sensor.
Cycle the door open and closed to clear any sticking safety limit switches. Step 4: Analyze System Variables and G-Code
Because the override function can bypass critical safety logic, it should only be used by qualified maintenance personnel. Always ensure that all "forced" signals are released before returning the machine to automatic production mode to avoid mechanical crashes or operator injury. 【报警】FANUC PMC"WN57 OVERRIDE FUNCTION IS ACTIVE" fanuc wn57 override function is active
Here is a comprehensive guide to understanding what the WN57 warning means, why it triggers, and how to clear it to restore standard operation. What is the WN57 Warning?
: In many Fanuc PMC (Programmable Machine Control) ladder designs, WN57 (or similar window markers) signals that a forced I/O or override mode is engaged. This can be used to prevent the machine from starting a cycle if the override is set too low (stalling the tool) or too high for a specific setup.
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While this is typically classified as a warning rather than a hard system alarm, it indicates that the machine is operating under altered conditions. Understanding why this warning appears, what it means for your production, and how to safely resolve it is critical for maintaining efficient CNC operations. What Does the WN57 Warning Mean? The "Override Function" allows an operator or technician
If this "override" or "force" function is left on, it can prevent normal PMC operation, such as closing a door safety interlock or allowing a turret to index, because the system thinks the forced state is the only state. Why Did the WN57 Alarm Appear? The WN57 Override function is active alarm appears because:
If any of these signals are "1" (active) and you attempt to transition from STOP to START or EDIT to MEM, the PMC explicitly sets the in the message table (address range: 3000-4000 in the message list).
To clear the WN57 warning and restore normal operations, follow these steps: Step 1: Inspect the Physical Dials
The override function is a developer's tool for debugging and testing the machine's ladder logic. Ladder logic (the PMC's program) consists of conditional statements based on input signals (like from limit switches) that determine output signals (like starting a motor). This tool allows programmers to temporarily bypass real-world inputs and set a signal to "1" (ON) or "0" (OFF) to test how the program responds. This is crucial for simulating faults without physically triggering a sensor. WN57 will stay active until the safety conditions
The "WN57 Override Function is Active" message is a generated by the FANUC PMC (Programmable Machine Controller) [1].
If the warning persists after resetting all physical switches, cycle the main breaker power to the CNC machine. This clears any latched registers in the volatile memory that may be falsely reporting an active override state. Summary of Best Practices Impact on WN57 Warning Set Dials to Clears basic manual switch overrides. Close Enclosure Doors Satisfies safety interlocks; removes speed restrictions. Toggle Dry Run Off Restores programmed -code control. Check PMC Ladder
The machine will typically continue to run the program.
Search for the override signals (commonly mapped to G-bytes or F-bytes in FANUC logic, such as the Feedrate Override signals G0012 ).
If the message persists, it means the PMC still thinks a condition is being overridden. A maintenance technician may need to look at the CNC diagnostic screens (PMC -> PMCDGN -> STATUS) to identify which input is forcing the override, often listed under specific diagnostic addresses.