What causes KUKA Robot alarm KRC0656?

Assignment of a local BOOL variable containing runtime calculation results to $CYCFLAG. Incorrect scope usage attempting to persist local variable state using $CYCFLAG. Confusion between local variable scope and system variable scope in KRL declarations. Migration of code from non-kernel-controlled flagging systems that did not respect $CYCFLAG restrictions. Attempt to pass local sensor or input data through $CYCFLAG for motion synchronization.

How do I fix KUKA Robot alarm KRC0656?

1. Identify the exact line in the KRL source code where local runtime data is assigned to $CYCFLAG 2. Determine the purpose of the local variable and whether it truly needs $CYCFLAG or should use a different mechanism 3. If synchronization is required, use appropriate KRL synchronization primitives such as WAIT FOR or signal variables instead 4. If the data must persist across cycles, declare it as a global variable or use permanent memory storage outside $CYCFLAG 5. Refactor the code to separate runtime data handling from cycle flag management per KUKA KRL best practices 6. Validate the corrected program in WorkVisual and perform functional testing on the robot control system

KUKA Robot codes

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KUKA Robot Controller

System · Advanced

Alarm KRC0656

KUKA Robot KRC0656 - Assignment of runtime value to $CYCFLAG inadmissible

A runtime value from local KRL data has been assigned directly to a $CYCFLAG variable. The $CYCFLAG variable is reserved for cycle synchronization and cannot be assigned local runtime data due to kernel-level state management constraints in the KRC4 controller. This programming error breaks the intended cycle flag protocol.

KUKA RobotSystemAdvanced

KRC0656

KUKA Robot KRC0656 - Assignment of runtime value to $CYCFLAG inadmissible

Assignment of runtime value to $CYCFLAG inadmissible

Common Causes

Assignment of a local BOOL variable containing runtime calculation results to $CYCFLAG
Incorrect scope usage attempting to persist local variable state using $CYCFLAG
Confusion between local variable scope and system variable scope in KRL declarations
Migration of code from non-kernel-controlled flagging systems that did not respect $CYCFLAG restrictions
Attempt to pass local sensor or input data through $CYCFLAG for motion synchronization

Troubleshooting Steps

1Identify the exact line in the KRL source code where local runtime data is assigned to $CYCFLAG
2Determine the purpose of the local variable and whether it truly needs $CYCFLAG or should use a different mechanism
3If synchronization is required, use appropriate KRL synchronization primitives such as WAIT FOR or signal variables instead
4If the data must persist across cycles, declare it as a global variable or use permanent memory storage outside $CYCFLAG
5Refactor the code to separate runtime data handling from cycle flag management per KUKA KRL best practices
6Validate the corrected program in WorkVisual and perform functional testing on the robot control system

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