P2028

Code

P2028

Message

REF() operand must be a simple variable

This error occurs when the REF() operator is applied to something other than a simple variable. The REF() operator creates a reference (pointer) to a variable, and the operand must be a named variable.

Example

The following code will generate error P2028:

PROGRAM Main
    VAR
        x : REF_TO INT;
    END_VAR

    x := REF(42);  (* Error: REF() operand must be a variable, not a literal *)
END_PROGRAM

To fix this error, use a named variable as the operand:

PROGRAM Main
    VAR
        counter : INT;
        x : REF_TO INT;
    END_VAR

    x := REF(counter);  (* Correct: counter is a simple variable *)
END_PROGRAM

Think IronPLC is wrong about this?

If you believe this diagnostic is incorrect, open an issue on GitHub with a small sample that demonstrates the problem.