Fanuc Keep Relay Parameters Exclusive Jun 2026

A service engineer needs to add a new M-code to the PLC, but the "Edit Ladder" option is greyed out (disabled). Solution: The engineer investigates the System Keep Relays. He finds that K18.6 (Edit Permitted) is set to 0. Furthermore, the ladder logic scans K18.6 every cycle and forces it to 0 if someone tries to set it to 1. The only way to bypass this exclusivity is to find the specific input (perhaps a hidden DIP switch or another K parameter) that the builder programmed to override the lock.

Exclusive Keep Relays are useless without a memory map. FANUC does not standardize these for machine builders. K10.0 might mean "Chip Conveyor Installed" on a Mori Seiki, but "High Pressure Coolant" on an Okuma. If you lose the electrical drawings or the PMC ladder printout, troubleshooting becomes a nightmare.

Some K-parameters require a full CNC power-down and restart to take effect, while others work instantly. Conclusion

measure elapsed time for sequences such as clamp-hold delays or spindle stabilization periods. When a timer counts down or up, it automatically resets to its preset value. Timers are volatile in run-time state but non-volatile in preset value—their accumulated current value resets at power‑off, but the preset value remains. fanuc keep relay parameters exclusive

Temporarily shielding external alarms or bypassing faulty sensor inputs (e.g., conveyor rotation detection) to keep the machine running. Safety & Interlocks: Managing interlocks such as chuck clamp signals or ATC (Automatic Tool Changer) safety conditions. System Configuration:

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

Do you have the from your machine builder? Share public link A service engineer needs to add a new

Standard user K parameters can be edited through the PMC parameter maintenance screen and are generally safe to modify—provided you have consulted your machine builder’s ladder documentation.

Press the right extension softkey ( > ) until you see (PMC Maintenance) or PMC . Press PMC MNT , then press the K-PARAM softkey.

Mastering how to safely identify, access, edit, and preserve Keep Relays grants you deeper control over your FANUC-driven machinery. Always treat exclusive system relays with the caution they demand—document your changes, maintain verified backups, and consult official FANUC documentation before modifying an unfamiliar bit. With this knowledge, you can unlock hidden functionalities, solve complex automation challenges, and maintain robust, reliable CNC operations. Furthermore, the ladder logic scans K18

Use the cursor keys to find the specific K-address (e.g., K0005). Bits are numbered from left to right. Type the new bit value ( 0 or 1 ) and press INPUT . Reset Safety :

This is where the concept of exclusivity becomes critical. Not every K parameter is there for the machine builder or the end user to program. These are often called "System Keep Relays," and they represent the highest level of exclusivity.

— Some exclusive K relays directly control emergency stop behavior or hardware interlocks. Changing them outside FANUC specifications can create hazardous conditions.

The range is the first exclusive block. These parameters are specifically designed to control fundamental PMC operation settings and software editing environments.