Fanuc Keep Relay Parameters Exclusive Access

Designating specific axes to operate in either standard mode or special indexing modes. How to Modify Keep Relay Parameters

Press the key, find the "SETTING" soft key, and change "PARAMETER WRITE" from 0 to 1. Navigate to PMC Maintenance: Press the [SYSTEM] function key.

: With known settings consistently applied, troubleshooting becomes more straightforward, as the system's behavior is more predictable.

Are you trying to (e.g., a 4th axis, a bar feeder, or a coolant system)? What specific alarm is the machine currently displaying? fanuc keep relay parameters exclusive

| | Description | Volatility | | :--- | :--- | :--- | | X | Input signals from machine hardware (sensors, buttons) | Volatile | | Y | Output signals to machine hardware (solenoids, motors) | Volatile | | F/G | Signals between the PMC and the CNC core | Volatile | | R | Internal relays for temporary logic storage | Volatile | | T/C | Timers and counters | Non-volatile | | K | Keep Relays – configuration switches | Non-volatile | | D | Data tables for storing numeric data | Non-volatile |

What makes them exclusive is that they are readable or writable by the part program (G-code). Standard CNC codes like G10 or system variables cannot modify a Keep Relay. They exist purely for the machine’s internal logic, making them a “private” communication channel between the machine builder and the maintenance engineer, bypassing the operator and the part programmer.

Technicians often use keep relays to temporarily disable door interlocks during maintenance or setup, though this should be handled with extreme caution as it overrides safety features. Designating specific axes to operate in either standard

FANUC Keep Relays are the "permanent memory" of your CNC machine's configuration. By mastering how to navigate to the SYSTEM →right arrow →right arrow

In PMC ladder design, refers to a control scheme where two or more Keep Relay bits must never be active simultaneously. If both bits are set to 1 at the same time, it creates conflicting instructions within the PLC ladder, leading to unpredictable machine behavior, hang-ups, or severe structural collisions. Why Exclusivity Matters

During power loss, a K parameter can record which step of an automated process (like a tool change) is currently active, enabling the machine to resume safely from the correct step upon restart. | | Description | Volatility | | :---

So, how does FANUC protect these exclusive system keep relays from being changed by accident? They utilize a multi-layered security approach:

— Restoring a full SRAM backup from one machine to another can corrupt exclusive K relay states, causing unexpected alarms or improper axis behavior.