E0023: a * address that VAR_CONFIG does not complete

Every variable declared AT %I*, %Q* or %M* gets its address in the configuration’s VAR_CONFIG, once for every instance of the program or function block that declares it; one missing is an error (Ed.3 6.5.5.4).

The path starts with the resource (when the configuration names its resources), then the program instance, the function block instances, and the variable:

PROGRAM line
VAR pump : valve; END_VAR
END_PROGRAM

CONFIGURATION plant
  RESOURCE cpu ON PLC
    TASK fast (INTERVAL := T#10ms, PRIORITY := 1);
    PROGRAM main WITH fast : line;     (* E0023: cpu.main.pump.coil *)
  END_RESOURCE
  VAR_CONFIG
    (* the fix: *)
    (* cpu.main.pump.coil AT %QX0.0 : BOOL; *)
  END_VAR
END_CONFIGURATION

The error points at the program instance whose variable has no address.