What causes KUKA Robot alarm KRC0491?

Missing initialization of $APO structure variables before PTP or LIN motion commands. Deletion or commented-out approximation parameter declarations in the initialization section. Incomplete migration of legacy KRL code that relies on default approximation values. Using motion instructions with approximation flags enabled without corresponding $APO variable definitions. Corrupted or incomplete program download where initialization blocks were not transferred.

How do I fix KUKA Robot alarm KRC0491?

1. Review the KRL program and locate all motion instructions using approximation (PTP or LIN with $APO syntax) 2. Add explicit initialization statements for $APO.VEL, $APO.ROB, $APO.DIS, and $APO.ORI in the program initialization section 3. Verify that approximation parameters are defined with appropriate data types and values matching your application requirements 4. Check the KUKA smartPAD program editor for syntax errors or missing variable declarations in included files 5. Perform a complete program download through WorkVisual or smartPAD to ensure all initialization code is transmitted to the controller 6. Test the program execution starting from the beginning to confirm all approximation variables are properly initialized before motion execution

KUKA Robot codes

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KUKA Robot Controller

Program/G-code · Advanced

Alarm KRC0491

KUKA Robot KRC0491 - Approximation not programmed <approximation criterion>

This alarm indicates that motion approximation parameters have not been properly initialized before executing a motion instruction. The system requires explicit assignment of approximation criteria variables such as $APO.VEL, $APO.ROB, $APO.DIS, and/or $APO.ORI to define the blending behavior at waypoints.

KUKA RobotProgram/G-codeAdvanced

KRC0491

KUKA Robot KRC0491 - Approximation not programmed <approximation criterion>

Approximation not programmed <approximation criterion>

Common Causes

Missing initialization of $APO structure variables before PTP or LIN motion commands
Deletion or commented-out approximation parameter declarations in the initialization section
Incomplete migration of legacy KRL code that relies on default approximation values
Using motion instructions with approximation flags enabled without corresponding $APO variable definitions
Corrupted or incomplete program download where initialization blocks were not transferred

Troubleshooting Steps

1Review the KRL program and locate all motion instructions using approximation (PTP or LIN with $APO syntax)
2Add explicit initialization statements for $APO.VEL, $APO.ROB, $APO.DIS, and $APO.ORI in the program initialization section
3Verify that approximation parameters are defined with appropriate data types and values matching your application requirements
4Check the KUKA smartPAD program editor for syntax errors or missing variable declarations in included files
5Perform a complete program download through WorkVisual or smartPAD to ensure all initialization code is transmitted to the controller
6Test the program execution starting from the beginning to confirm all approximation variables are properly initialized before motion execution

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