Switching between manual and automatic door interlock behaviors.
In PMC ladder logic maintenance, specific addresses may be processed using Exclusive-OR
: Toggling this bit may allow or prevent on-machine editing of the PMC ladder.
While keep relays vary by machine builder, here are common examples used in the industry: fanuc keep relay parameters exclusive
Here are some common issues that may occur with Fanuc keep relay parameters exclusive:
Here are some best practices for maintaining Fanuc keep relay parameters exclusive:
Complete Guide to FANUC Keep Relay Parameters: Troubleshooting, Logic, and Safety Because they are stored in non-volatile memory, they
Keep relays are specialized 8-bit registers—represented from bit 0 to bit 7—that store critical logic states. Because they are stored in non-volatile memory, they serve as the "permanent memory" for a machine's logic operations. These parameters are generally split into two categories:
When set to 1, it becomes impossible to modify these screens, even if they are visible. 3. How to Access and Modify Keep Relays
Locate the (PWE) setting. Change it from 0 to 1. The control will likely throw an alarm (e.g., Write Enable Parameter ). This is normal. Access the PMC Screen: Press the SYSTEM hard key. How to Access and Modify Keep Relays Locate
Standard FANUC manuals do not define what specific keep relays do. The Machine Tool Builder (OEM) decides their functions. Check the machine's electrical manual for the PMC parameter list.
Often used for system-level options like bypassing sensor inputs (e.g., chip conveyor detection). Builder-Specific Examples
Never guess what a keep relay bit does. Fanuc provides the infrastructure, but the Machine Tool Builder decides what bits K00 through K89 control. Look up the specific machine’s electrical manual or PMC parameter list.
to enable or disable specific machine options, logic flows, or hardware configurations without rewriting the PLC ladder. Key Characteristics of Exclusive Keep Relays Non-volatile Storage:
Some machines require the Emergency Stop to be depressed or the PMC to be stopped before certain system bits can be modified. Fanuc PMC - Keep Relays (K Parameter) Explained in English