Fanuc Keep Relay Parameters Exclusive Jun 2026

Use the arrow keys to navigate to the exact keep relay address and bit you want to change (e.g., K5.4). Type the new value (1 for ON, 0 for OFF) and press . Finalize and Reset: Revert the Parameter Write Enable (PWE) back to 0. Press the RESET key to clear the parameter write alarm.

Unlike standard relays, Keep Relays "keep" their state (1 or 0) even after the machine is powered off. Bit-Level Logic:

They typically control machine-specific options like auto-door behavior, chip conveyor timers, or enabling a 4th axis. Documentation: Because they are builder-defined, the meanings of cap K 99.9 fanuc keep relay parameters exclusive

Used to override the proximity switch signal for a chuck, often used when setting up custom fixtures that do not trigger the standard sensor.

Follow these steps to safely access and adjust K parameters. Use the arrow keys to navigate to the

When set to 1, this "hides" the Timer, Counter, Keep Relay, and Data Table screens entirely. K902.7 / K19.7 (PROTECT PMC PARAM):

Furthermore, the exclusivity of Keep Relay parameters extends to their role in system configuration and customization. Unlike standard internal relays, which are purely for the programmer’s logical processing, Keep Relays often bridge the gap between the PMC (Programmable Machine Controller) and the CNC system parameters. In many FANUC architectures, specific Keep Relays are hard-coded or reserved for system-level functions. For example, a specific bit in a Keep Relay might be used to enable a custom macro interface or activate a specific safety interlock that must remain active regardless of power cycles. In custom machine building, these relays are frequently used to create "personality bits"—settings that allow a single generic ladder program to adapt to different machine variants (e.g., a lathe versus a mill) by simply flipping a Keep Relay switch. Press the RESET key to clear the parameter write alarm

This example assumes a FANUC 0i controller.

Selecting between specific tool change recovery methods or pallet change sequences where two conflicting mechanical actions cannot happen simultaneously.