What causes KUKA Robot alarm KRC0898?

Left operand in a boolean expression is declared or initialized as INT, REAL, or CHAR instead of BOOL. Variable type mismatch in conditional statements (IF, WHILE, UNTIL) where a non-boolean expression is used. Function or subroutine returning a non-boolean value assigned to a boolean operand. Incorrect casting or type conversion from numeric or string types to boolean without explicit conversion. Copy-paste error where a boolean variable was replaced with a different variable type without updating the operation logic.

How do I fix KUKA Robot alarm KRC0898?

1. Review the KRL source code at the line indicated in the error message and identify the boolean operation causing the alarm 2. Verify the data type declaration of the left operand variable using the variable declaration list or hover inspection 3. Confirm the left operand is explicitly declared as BOOL type; if not, change the declaration or convert the value to BOOL 4. Check function return types if the left operand is assigned from a function call; ensure it returns a BOOL 5. Use explicit type conversion functions (e.g., INT_TO_BOOL) if intentionally converting from another data type 6. Recompile the KRL program after corrections and test the logic flow to ensure the boolean operation executes correctly

KUKA Robot codes

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KUKA Robot Controller

System · Basic

Alarm KRC0898

KUKA Robot KRC0898 - LEFT OPERAND NOT EQUAL TO BOOL 2234

This alarm occurs when a KRL program attempts to perform a boolean operation on a left operand that is not of boolean data type. The compiler/interpreter expects a BOOL value but received an incompatible data type instead, preventing the logical operation from executing.

KUKA RobotSystemBasic

KRC0898

KUKA Robot KRC0898 - LEFT OPERAND NOT EQUAL TO BOOL 2234

LEFT OPERAND NOT EQUAL TO BOOL 2234

Common Causes

Left operand in a boolean expression is declared or initialized as INT, REAL, or CHAR instead of BOOL
Variable type mismatch in conditional statements (IF, WHILE, UNTIL) where a non-boolean expression is used
Function or subroutine returning a non-boolean value assigned to a boolean operand
Incorrect casting or type conversion from numeric or string types to boolean without explicit conversion
Copy-paste error where a boolean variable was replaced with a different variable type without updating the operation logic

Troubleshooting Steps

1Review the KRL source code at the line indicated in the error message and identify the boolean operation causing the alarm
2Verify the data type declaration of the left operand variable using the variable declaration list or hover inspection
3Confirm the left operand is explicitly declared as BOOL type; if not, change the declaration or convert the value to BOOL
4Check function return types if the left operand is assigned from a function call; ensure it returns a BOOL
5Use explicit type conversion functions (e.g., INT_TO_BOOL) if intentionally converting from another data type
6Recompile the KRL program after corrections and test the logic flow to ensure the boolean operation executes correctly

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