A CLASS hierarchy is exported flat - Manual - Software Loader - The AX SIMATIC SW-Loader. - Software Loader (sld),tool

In exception to this rule a CLASS hierarchy is exported flat for the three reasons:

• in order to avoid the restriction of 8 levels on a SIMATIC PLC which reached in typical architectural designs quite easily
• to prove the same model as in ST programming, where members of a base class can be access from derived classes (same name scope)
• to harmonize the behavior in both workflows TIAX library and TIAX direct loading

'Flat' means that all variables of a class hierarchy are collected in the final class type. In the following example there will be four variables accessible for the type SpecificMotorA: Run (RW), ReverseDirection (RW), ActualVelocity (RO) and MaxAcceleration (RW).

CONFIGURATION config
    VAR_GLOBAL
        {S7.extern=ReadWrite}
        mot1 : SpecificMotorA;
    END_VAR
END_CONFIGURATION

{S7.extern=ReadWrite}
CLASS ABSTRACT AbstractMotor
    VAR PUBLIC
        Run               : BOOL;
        ReverseDirection  : BOOL;
    END_VAR
    ...
END_CLASS

{S7.extern=ReadWrite}
CLASS GenericMotor  EXTENDS AbstractMotor
    VAR INTERNAL
        {S7.extern=ReadOnly}
        ActualVelocity    : LReal;
    END_VAR
    ...
END_CLASS

{S7.extern=ReadWrite}
CLASS SpecificMotorA  EXTENDS GenericMotor
    VAR INTERNAL
        {S7.extern=ReadWrite}
        MaxAcceleration    : LReal;
    END_VAR
    ...
END_CLASS