MODBUS TCP OVERVIEW

All IEC-1131 data types are represented on Modicon PLC’s in little-endian form. Examples follow

BYTE

8-bit quantity.
Bits 7 - 0 of register = Bits 7 - 0 of BYTE

DINT

32-bit quantity.
Bits 15 - 0 of first register = bits 15 - 0 of DINT
Bits 15 - 0 of second register = bits 31 - 16 of DINT

INT

Bits 15 - 0 of register = bits 15 - 0 of INT

REAL

32-bit Intel single precision real
Bits 15 - 0 of first register = bits 15 - 0 of REAL (bits 15 - 0 of significand)
Bits 15 - 0 of second register = bits 31 - 16 of REAL (exponent + bits 23 - 16 of significand)

UDINT

32-bit quantity.
Bits 15 - 0 of first register = bits 15 - 0 of UDINT
Bits 15 - 0 of second register = bits 31 - 16 of UDINT

UINT

Bits 15 - 0 of register = bits 15 - 0 of INT

For any others, see the appropriate IEC-1131 programming manuals