Buffer endianness - Manual - SIMATIC AX - System.Serialization

By default, the serialized result in the buffer is little-endian (i.e. the least significant byte of the value is stored in the smallest address). In the example below, t[0] = 16#35, t[1] = 16#12. As return value of the Serialize function, nextValueOffset = start offset + value byte length = 2 + 2 = 4.

USING System.Serialization;

FUNCTION SerDe_Demo
    VAR_TEMP
        data : ARRAY[0..5] OF BYTE;
        nextValueOffset: INT;
    END_VAR

    // data = [0x0, 0x0, 0x35, 0x12, 0x0, 0x0]
    // nextValueOffset = 4
    nextValueOffset := Serialize(2, UINT#16#1235, data);
END_FUNCTION

The endianness can be specified/changed by passing an additional argument to the Serialize function or by using the SerializeLitte or SerializeBig function, respectively:

USING System.Serialization;

FUNCTION SerDe_Demo
    VAR_TEMP
        data : ARRAY[0..5] OF BYTE;
        nextValueOffset : UDINT;
    END_VAR

    // Serialization using big endianness
    // data = [0x0, 0x0, 0x12, 0x35, 0x0, 0x0]
    // nextValueOffset = 4
    nextValueOffset := Serialize(UDINT#2, UINT#16#1235, data, Endianness#Big);

    // Alternative for a serialization using big endianness
    // data = [0x0, 0x0, 0x12, 0x35, 0x0, 0x0]
    // nextValueOffset = 4
    nextValueOffset := SerializeBig(UDINT#2, UINT#16#1235, data);
END_FUNCTION

Buffer endianness - Manual - SIMATIC AX - System.Serialization - System.Serialization,

System.Serialization library