Detects code locations where a null pointer is possibly dereferenced
Justification: A pointer should be checked before each dereferencing to make sure it is not equal to zero. Otherwise an access violation may occur at runtime.
Importance: High
Example
PROGRAM PLC_PRG VAR ptiVar1:POINTER TO INT; ptiVar2:POINTER TO INT; ptiVar3:POINTER TO INT; iVar:INT; iCount :INT; iCondition: INT; END_VAR iCount := iCount + INT#1; ptiVar1 := ADR(iVar); ptiVar1^ := iCondition; // OK - valid reference ptiVar2^ := iCondition; // SA0039 - null pointer dereferenciation iVar := ptiVar3^; // SA0039 - null pointer dereferenciation --> SA0039: Possible null pointer dereference 'ptiVar2^' --> SA0039: Possible null pointer dereference 'ptiVar3^'