Compiler Warning C0567

Message: Interface <interface name 1> does not extend __System.IQueryInterface

Possible cause: Every interface of an interface library has to extend __System.IQueryInterface. The used interface does not extend __System.IQueryInterface.

Example 500. Example

PROGRAM PLC_PRG
VAR
    ITFref : ITF;
    ITFref2 : ITF2;
END_VAR

INTERFACE ITF
INTERFACE ITF2 EXTENDS ITF

Message:

C0567: Interface ITF does not extend __System.IQueryInterface

Correction:

INTERFACE ITF EXTENDS __System.IQueryInterface

For an overview of all rules to be followed for interface libraries, see: Interface Libraries