Compiler Error C0140
Message: Reference assign is only allowed to variables of Reference type
Possible error cause: An attempt is made to assign a reference value to a variable not defined as a reference type.
Error correction: Define the variable as a reference type.
Example 402. Example of the error:
PROGRAM PLC_PRG
VAR
    i : INT;
    I_r : INT;
END_VAR
I_r REF= i;
Message:
C0140: Reference assign is only allowed to variables of Reference type
Error correction:
I_r : REFERENCE TO INT;