Fanuc Wn57 Override Function Is Active

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.

Final recommendation

| 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.

WN57 OVERRIDE FUNCTION IS ACTIVE message on a Fanuc CNC is a PMC (Programmable Machine Control) alarm indicating that the "Override" mode for the forced I/O function is currently enabled

This is a debugging feature typically used during the setup or maintenance of PMC programs to force signals into a specific state. While active, it can prevent the PMC program from operating normally, as forced signals may override actual machine logic. How to Disable the WN57 Warning

To clear this alarm and return the machine to its standard operating state, you must turn off the override function: Via PMC Parameters Screen: Navigate to the PMC Parameter setting screen on your CNC control. Locate the (倍率) function option. Move the cursor to this setting and change it to "Disabled" Restart the CNC to clear the alarm. Via Keep Relay (K-Address): The override function is often mapped to keep relay Directly changing the value of K906.0 to 0

will disable the function and should clear the WN57 message. Why This Message Appears Debugging/Testing:

An engineer or technician may have left the function on after troubleshooting the ladder logic or testing I/O signals. Multi-Path Limitations:

On Series 30i/31i/32i controls, this override function can only be active for up to three PMC paths

simultaneously. If four or more paths are set to override mode, you may encounter related errors like ER47 ILLEGAL OVERRIDE FUNCTION SETTING Keep Relay screen for your particular Fanuc control series?

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?

The red LED on the control panel blinked incessantly, a silent scream in the otherwise quiet machine shop.

Elias wiped grease from his forehead with the back of a hand, leaving a dark smear. He stared at the Fanuc Series 0i-TF screen. The machine, a battered but reliable Okuma lathe they called "Old Bess," had stopped mid-cut.

On the display, in crisp, alarming green text, sat the message: WN57: OVERRIDE FUNCTION IS ACTIVE.

"Come on, Bess," Elias muttered. "Not today. We got a truck leaving at four."

He pressed the Reset button. The message flickered, held for a second, and reappeared. The spindle sat locked. The axis motors hummed a low, waiting tone, but the G-code execution was paused. The machine was effectively saying, I’m not moving until you look at what I’m seeing.

Elias sighed, grabbing his worn Fanuc manual from the toolbox. He knew WN57 wasn't a fatal crash. It wasn't a servo alarm or a blown fuse. It was a warning—a logic gate. It meant a safety interlock had been tripped, usually by the operator trying to speed things up or bypass a step in a rigid tapping cycle.

He toggled the Mode switch to MDI (Manual Data Input). He typed in a simple command to index the turret.

WN57: OVERRIDE FUNCTION IS ACTIVE.

"She’s stubborn today," said a voice from behind.

Elias turned to see Marcus, the shop foreman, leaning against a pillar, sipping coffee. "She’s not stubborn, she’s confused. I didn't touch the override knob. I was running at 100% feed."

Marcus walked over, his eyes scanning the messy control panel. "Check the parameters. Maybe someone messed with the skip blocks."

Elias keyed into the Parameter screen, navigating to the diagnostics. He was looking for the system bits that controlled feed hold and override signals. To a novice, the screen was a wall of binary noise—zeros and ones in rows. To Elias, it was a heartbeat.

He found the bit. Signal G008.6: Spindle Override Active. fanuc wn57 override function is active

"See?" Elias pointed. "The computer thinks I’m holding down the override button. But look." He spun the physical override dial on the panel back and forth. The on-screen percentage readout tracked it perfectly. 50%. 100%. 150%. It should have been clear.

"It’s ghosting," Marcus said. "Loose wire in the back. Probably the vibration from that heavy roughing cut you took earlier."

"Great," Elias groaned. He didn't have time to pull the back panel off and check the terminal blocks. The part was a titanium aerospace bracket; one wrong move and the tool would snap, costing them three hours of re-tooling.

He tapped the Diagnostic soft key again. The WN57 alarm was a "Watchdog" type. It meant the PLC (Programmable Logic Controller) was waiting for a specific condition to go low before it allowed the CNC to proceed. Usually, clearing an override alarm was simple: return the dial to 100% and hit Cycle Start.

Elias did exactly that. He checked the dial. It sat perfectly at the detent for 100%. He hit Cycle Start.

The spindle ramped up, the tool moved forward... and stopped instantly. The red LED flashed.

WN57: OVERRIDE FUNCTION IS ACTIVE.

"She’s really not liking it," Elias said, frustration creeping into his voice. "It’s like the system thinks the dial is stuck at zero, even though the screen says 100%."

"Maybe it's not the dial," Marcus suggested, setting his coffee down. He pointed to a small, unassuming button on the lower right of the panel, partially obscured by a chip guard. "Check the Dry Run switch."

Elias blinked. He reached over and toggled the Dry Run switch on, then off. It clicked firmly.

"Wait," Elias whispered. He looked at the G-code program currently loaded. It was a complex macro program imported from the main office. It used G31 (Skip Function) probes.

He scrolled through the code on the screen. N50 G31 Z-2. F100. N60 WN57...

"Wait a second," Elias muttered. "The alarm isn't hardware. It's in the program."

He scrolled up to the header variables. The programmer had inserted a safety logic check. It was looking for a specific input state. If the machine detected any external override signal—like a feed hold or a dry run active—during the probing cycle, it triggered a user-defined macro alarm (WN57) to prevent the probe from crashing into the part due to incorrect feed

This Fanuc message indicates that a customized Override Function (WN57)

is currently active within the PMC (Programmable Machine Control)

, typically used to modify feedrates, rapid traversals, or spindle speeds specifically for authorized machine operations. Overview of Fanuc WN57 Override

Usually mapped to custom PLC/PMC logic to lock, limit, or force a specific override percentage, overriding the standard operator panel knobs. Operation:

When active, the feedrate or speed is dictated by the PMC logic rather than the physical operator panel dial. Where to Check: (PMC Maintenance) screens for the specific status of WN57. Potential Reasons for Activation Custom PMC Function:

A custom PMC function is currently running, often configured in the Robodrill or similar PMC-controlled machinery. Manual Intervention: Manual intervention occurred during an automatic cycle. System Macro Settings: System macro variable

may have been utilized to disable or set overrides programmatically. What to Do If Unintended Check Diagnostics: DIAGNOSTICS screen and look at status for (W-address 57) to determine if it is (Active) or (Inactive). Toggle Switch/Menu: Use the custom operator panel or softkey to disable the specific override function.

Press the [Reset] button to clear temporary custom PMC overrides.

For more tailored information, please verify if this is on a FANUC ROBODRILL OPERATOR'S MANUAL or a similar specialized machine.

FANUC Robodrill Operator's Manual | PDF | Direct Current - Scribd

The message "WN57 Override Function is Active" on a Fanuc control typically indicates that the machine's feedrate or speed override is being controlled by an external source or a specific internal safety setting, rather than the manual dial on the operator panel. Why This Message Appears

This is often a status notification rather than a hard error. It usually triggers in the following scenarios:

Override Select Function: The "Override Select" feature is enabled, which forces the robot or CNC to a specific speed regardless of where the physical knob is turned.

Production Checks: A "pre-flight" check might be active that requires the general override to be at a specific percentage (like 100%) before production can start.

External PLC Control: An external PLC or supervisor system is sending a signal to the controller to limit speed for safety or process consistency. How to Address or Reset It

If this message is preventing you from manually adjusting your speed, try these steps: Check Override Select Settings: Navigate to Menu > Setup > Override Select.

Verify if the function is set to ENABLED. If you want manual control back, change this to DISABLED. Verify UI Signals:

In some cases, specific "User Input" (UI) signals from a PLC force this state. Check your I/O status to see if *OVRD_ENB (Override Enable) or similar signals are being held high or low by external logic. Production Check Config: Go to Menu > Setup > Prog Select. If operator override: Return override knobs/panel to normal;

Look for a setting titled "General override < 100%" or similar. If this is active, the system may display the WN57 message to warn you that it is overriding your manual input to meet this requirement. System Variable Check:

Check the system variable $GENOV_ENB. If this is set to FALSE, manual override might be ignored in certain modes.

Note: If this message appeared suddenly after a crash or battery change, it may be related to a Safety PLC forcing a "slow mode" until a safety fault is cleared or the home position is re-established.

The "WN57 Override Function is Active" message on a Fanuc CNC typically refers to a specific condition within the PMC (Programmable Machine Control) ladder logic. This message is generally not an error code from the Fanuc system itself, but a custom operator message or warning defined by the Machine Tool Builder (MTB). Core Meaning

In most Fanuc implementations, a "WN" code refers to a Warning (as opposed to an "AL" for Alarm).

The Function: It indicates that an override setting—such as Feedrate Override, Spindle Override, or Rapid Traverse Override—is currently engaged or forced.

Safety Context: This message often triggers when the machine is in a "Setup" or "Maintenance" mode where standard safety interlocks (like door switches) are bypassed, or when the feedrate is locked to a specific percentage (e.g., 100%) to ensure predictable behavior during automated cycles. Common Causes & Solutions

If you see this message and need to clear it, check the following:

Override Switches: Ensure the physical feedrate or spindle override knobs on the operator panel are not stuck between positions.

Mode Selection: The message may appear if the machine is in Dry Run mode or if a Machine Lock function is active.

Keep Relays / Data Tables: Check the MTB's manual for specific Keep Relays (K) or Data Table (D) settings. Builders often use these to "latch" an override active for specific tasks.

PMC Forced I/O: If a technician was recently working on the machine, they may have used the Forced I/O function in the PMC to override a signal. Per the Fanuc 30i/31i/32i Handbook, an "Override Mode" of the forced I/O can be active for up to three paths simultaneously.

💡 Pro Tip: To find the exact trigger, go to the PMC Maintenance screen and search for the address associated with Message WN57. This will show you the exact ladder rung and the inputs required to satisfy the condition. Reference Documentation

For detailed troubleshooting of PMC messages and override settings, refer to the following official resources:

Fanuc CNC Function Catalog: For an overview of how override functions integrate with CNC controls.

Machine Tool Builder (MTB) Manual: Since "WN57" is builder-defined, your machine’s specific manual (e.g., Doosan, Mori Seiki, Haas) is the primary source for this specific code.

Are you trying to clear the warning to run a program, or are you intentionally activating an override for maintenance?**

Typical Remedies / Actions

If operator override: Return override knobs/panel to normal; release feed hold; cancel MPG jog modes.
If safety interlock: Fix the safety input (close door, reset safety relay), then reset the control per OEM procedure.
If communication/watchdog: Restore/repair network link or adjust watchdog timing/parameters as per OEM guidance.
If servo/drive warning: Investigate and repair drive or motor issues; clear alarms once root cause fixed.
If program or macro caused: Edit program to remove unwanted override calls; validate with dry-run.
If parameter-related: Only change parameters if authorized and documented; follow OEM/FANUC manuals.
If unclear: Contact machine OEM or service; provide diagnostics, axis status, and event logs.

Scenario 2: The Block Search Aftermath

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.

The "WN" Code Explained

FANUC alarms are categorized by prefixes:

SV (Servo Alarm): Issues with motors or drives.
PS (Program/Sequence Alarm): Errors in G-code or macro syntax.
SP (Spindle Alarm): Spindle drive or motor faults.
WN (Warning): A non-critical condition that restricts operation but does not indicate hardware damage.

WN57 specifically belongs to a family of safety and interlock warnings. It translates to: “The control is currently in a state where manual or automatic override functions are engaged, preventing the requested action.”

Step 3 – Check for active G-code overrides

Some controls activate WN57 with:

G10.6 P1 Rxxx;  (override active)
G10.9 P1 Rxxx;

Cancel with:

G10.6 P0;
G10.9 P0;

Frequently Asked Questions (FAQ)

Q: Is WN57 the same as EMG (Emergency Stop)? A: No. EMG is a hard stop (red alarm). WN57 is a soft warning (white/yellow message).

Q: Can I disable WN57 permanently? A: Yes, by modifying the PMC message table, but this is extremely dangerous and voids safety certifications. Never do this on a production machine.

Q: Does WN57 appear on FANUC 0i-Mate? A: Yes. The 0i-Mate series (common on lathes and mills) exhibits WN57 identically for Dry Run and Machine Lock functions.

Q: My machine shows WN57 but all switches are off. What now? A: Check for a stuck physical switch (internal contact failure). Use the FANUC diagnostic screen (DIAGNOSIS → PMC → SIGNAL) to see if G104.0 (MLK) reads "1" even when the switch is off. This indicates a hardware failure in the I/O unit.

This article is for informational purposes. Always consult your specific FANUC CNC manual and machine tool builder’s documentation before performing maintenance or altering operational procedures.

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 Scenario 2: The Block Search Aftermath After performing

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.

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

WN57: OVERRIDE FUNCTION IS ACTIVE is a PMC (Programmable Machine Control) warning indicating that the ladder program's "override" or "forced I/O" function is currently enabled.

This function is primarily used during debugging to force specific signals manually. To clear the warning, you must disable the override mode within the PMC parameters. Cause of the Alarm The alarm is triggered when the Override Mode

for PMC paths is active. This state is often left on accidentally after troubleshooting or machine setup. While active, the system may prevent the ladder program from executing correctly or may result in an

error if too many paths (typically four or more) are being overridden simultaneously. Course Hero Recovery Steps

To resolve this warning and return the machine to standard operating mode, follow these steps: Locate PMC Parameters : Navigate to the PMC Parameter settings screen on your controller. Disable Override : Find the Override Function

(often labeled as "Override Effective" or similar) and change its setting to "Inactive" Direct Parameter Change

: Alternatively, you can directly change the system K-address to disable the function.

: Once the setting is changed, restart the CNC to clear the warning message. Important Safety Note:

Ensure all maintenance or debugging tasks are complete before disabling this function, as it may impact signal monitoring used during setup. for other PMC signals on your Fanuc Controller

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:

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"

This message—"WN57 OVERRIDE FUNCTION IS ACTIVE"—appears on FANUC CNC controls (often on series like 0i, 30i, 31i, 32i, or 21i) when the control is operating in a special override mode that bypasses certain safety or standard operating limits.

Below is a practical operator & setup guide to understanding, handling, and clearing this condition.

Pro Tip for Programmers:

If you are writing a macro and want to check if an operator has left an override active, you can use system variables:

#3004 (Feed & Spindle Override disable)
#3006 (Stop with message)

However, WN57 is typically a built-in safety feature for FANUC Series 0i, 16i, 18i, 21i, and 31i controls.

Final Verdict: Check your override knobs. Set them all to 100%. The machine will then proceed.

Has anyone else encountered the WN57 alarm while rigid tapping? Share your experience below! 👇

#FANUC #CNC #Machining #Troubleshooting #WN57 #OverrideFunction

Here’s a useful, practical review of the "FANUC WN57 Override Function is Active" message, written for CNC operators and setup personnel.

Part 4: Technical Deep Dive – FANUC Ladder Logic & WN57

For maintenance engineers and integrators, understanding why WN57 triggers requires a look at the PMC (Programmable Machine Controller) ladder logic.

WN57 is not generated by the CNC core itself; it is generated by the PMC based on specific diagnostic signals. The CNC sends a "mode change request" to the PMC. The PMC checks the following signals (typical addresses – confirm against your ladder diagram):

| Function | FANUC Signal Name | Typical Address | | :--- | :--- | :--- | | Machine Lock 1 | G104.0 | G116.0 (older) | | Dry Run | G104.7 | G116.7 | | Aux Funct Lock | G104.1 | N/A | | Handle Interrupt Mode | Input from rotary switch | Varies |

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 WN57 message in the message table (address range: 3000-4000 in the message list).