Message: No definition found for base class '<function name>'
Possible error cause: The function block specified as the base does not exist or is not a function block.
Error correction: Use a function block as the base.
Example of the error:
PROGRAM PLC_PRG VAR inst : FB; END_VAR FUNCTION_BLOCK FB EXTENDS POU VAR END_VAR FUNCTION POU VAR END_VAR --> C00090: No definition found for base class 'POU'