Unlike CNC parameters that directly control numerical values such as feed rates or acceleration curves, Keep Relays are strictly binary (on/off) flags. Their primary and exclusive purpose is to interface with the machine’s —the internal PLC that handles all auxiliary functions like tool changers, coolant pumps, and safety doors.
: Tracking ongoing operations, such as signaling that a tool change is in progress so the machine can recover safely after a power failure. Structure and Addressing
Use the right arrow (expansion) soft keys until you see , then select PMCPRM or PMC MAINTENANCE . Select the KEEPRL soft key to view the bit table. Input the Data: Navigate to the desired address (e.g., K17). Type the new bit value (0 or 1) and press INPUT .
Because keep relays directly alter machine logic, Fanuc locks parameter editing by default to prevent accidental modifications that could cause machine crashes or operator injury. fanuc keep relay parameters exclusive
Always write down the original state of a keep relay before changing it. A small mistake can lead to significant machine downtime or safety hazards.
Press the System key, then use the soft keys to find PMC Maintenance > Keep Relay .
When attempting to enable a new parameter, you might encounter an error if you unknowingly violate an exclusive relationship. The Fanuc control will often display a PMC Alarm or halt axis movement. Follow these steps to diagnose and resolve the conflict: 1. Check the Ladder Diagram Unlike CNC parameters that directly control numerical values
Fanuc keep relays are organized in bytes. Each K-parameter number (e.g., K00, K01, K12) represents , numbered from 0 to 7.
Accessing Keep Relays is done through the SYSTEM screen on the FANUC operation panel. The process requires navigating through the PMC maintenance menus. Step-by-Step Access Method on the Machine Operation Panel. Navigate to PMC Maintenance: Press the right arrow button ( →right arrow ) to access the menu until you see [PMC] .
Ensure that any physical switches on the machine match the software state selected by the exclusive keep relay. For example, if a keep relay sets the machine to "Robot Loading Only," but the physical manual-override key is turned on, the PMC will halt all automatic cycles. Structure and Addressing Use the right arrow (expansion)
What are you trying to make exclusive?
Ensuring a pallet cannot be unclamped manually if the machine is running in automatic cycle.
In the world of FANUC CNC maintenance and customization, few tools are as powerful—or as misunderstood—as (often referred to as K-parameters). These non-volatile memory bits are the secret behind enabling, disabling, and customizing machine builder (OEM) functions within the Programmable Machine Controller (PMC).