What causes KUKA Robot alarm KRC0558?

Variable referenced in SYNACT instruction is declared as write-protected or read-only in the program declaration section. Variable scope issue where SYNACT block attempts to access a local variable outside its program unit definition. Variable has been deleted or renamed after SYNACT instruction was created, causing reference mismatch. Incorrect variable name spelling in the SYNACT block definition causing system to fail variable lookup. Variable is protected by SafeOperation restrictions or resides in a memory segment inaccessible during cyclic execution.

How do I fix KUKA Robot alarm KRC0558?

1. Locate the SYNACT instruction block and verify the exact variable name matches the declaration in your KRL program 2. Check the variable declaration to confirm it is not defined with READ_ONLY or PROTECTED attributes that prevent write access 3. Verify that the variable is declared in global scope or within the same program unit where the SYNACT block is executing 4. Review SafeOperation configuration in WorkVisual to ensure the target variable is not restricted by safety monitoring rules 5. Create a test variable without protection and temporarily reassign the SYNACT block to validate the instruction syntax works correctly 6. Recompile the program with detailed error reporting enabled and cross-reference variable names in both declaration and SYNACT usage

KUKA Robot codes

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KUKA Robot Controller

System · Advanced

Alarm KRC0558

KUKA Robot KRC0558 - Invalid SYNACT variable <variable name> <block number>

This alarm occurs during cyclic SYNACT monitoring when the KRC4 controller encounters an access error on a specified variable in logical comparison or value assignment operations. The variable may be write-protected, deleted, out of scope, or inaccessible due to memory protection or data type incompatibility.

KUKA RobotSystemAdvanced

KRC0558

KUKA Robot KRC0558 - Invalid SYNACT variable <variable name> <block number>

Invalid SYNACT variable <variable name> <block number>

Common Causes

Variable referenced in SYNACT instruction is declared as write-protected or read-only in the program declaration section
Variable scope issue where SYNACT block attempts to access a local variable outside its program unit definition
Variable has been deleted or renamed after SYNACT instruction was created, causing reference mismatch
Incorrect variable name spelling in the SYNACT block definition causing system to fail variable lookup
Variable is protected by SafeOperation restrictions or resides in a memory segment inaccessible during cyclic execution

Troubleshooting Steps

1Locate the SYNACT instruction block and verify the exact variable name matches the declaration in your KRL program
2Check the variable declaration to confirm it is not defined with READ_ONLY or PROTECTED attributes that prevent write access
3Verify that the variable is declared in global scope or within the same program unit where the SYNACT block is executing
4Review SafeOperation configuration in WorkVisual to ensure the target variable is not restricted by safety monitoring rules
5Create a test variable without protection and temporarily reassign the SYNACT block to validate the instruction syntax works correctly
6Recompile the program with detailed error reporting enabled and cross-reference variable names in both declaration and SYNACT usage

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