Fanuc Keep Relay Parameters — Exclusive

Exclusive parameters prevent conflicting machine states that could cause catastrophic mechanical crashes or safety hazards.

By respecting the architecture of exclusive keep relay parameters, you ensure that any optimizations or feature toggles you introduce remain fully aligned with the machine's built-in safety logic.

Modifying Keep Relays requires navigating to the PMC parameter screens. Because these settings alter machine behavior, the control enforces a write-protection protocol. Step 1: Enable Parameter Writing fanuc keep relay parameters exclusive

Keep relays are used by machine tool builders (MTBs) to define machine behavior without rewriting the PLC ladder. They are typically used for:

A: The number varies by control model and PMC type. Many systems define K0 through K39 and include additional data tables such as C0 through C199 for counters. Because these settings alter machine behavior, the control

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FANUC provides the control platform, but the Machine Tool Builder (e.g., Doosan, Mazak, Mori Seiki) writes the Keep Relay definitions. Always use the manual provided by the builder, not standard FANUC manuals, to decode K-parameters. Many systems define K0 through K39 and include

In more complex setups, an entire byte (8 bits) of a keep relay might govern a specific subsystem, such as an automatic tool changer (ATC) or an indexing table. Within that byte, only one specific bit is allowed to be active ( 1 ) at any given time. Activating more than one bit simultaneously creates a logic conflict, resulting in PMC alarms or unexpected machine behavior. Common Applications of Exclusive Keep Relays