32-bit floating point format - GMW83 - GMW83A - GMW83D - GMW83DRP - GMW83DRPC - GMW83RPC - GMW84 - GMW84S - GMW86P - GMW87M

GMW80 Series User Guide

Document code
M211748EN
Revision
H
Language
English
Product
GMW83
GMW83A
GMW83D
GMW83DRP
GMW83DRPC
GMW83RPC
GMW84
GMW84S
GMW86P
GMW87M
Document type
User guide

Registers using 32-bit float data format are encoded using the binary32 encoding defined in IEEE 754. The format is also known as "single-precision floating point format".

The least significant 16 bits of a floating point number are placed at the Modbus register listed in the table, while the most significant 16 bits are placed in the register with number/ address + 1, as specified in Open Modbus TCP Specification, Release 1.0. This is also known as "little-endian" or "Modicon" word order.

Despite the specification, some Modbus masters may expect a "big-endian" word order (most significant word first). In such case, you must select "word-swapped" floating point format in your Modbus master for the Modbus registers of the device.

A complete 32-bit floating point or integer value should be read in a single Modbus transaction.
Reading the measurement data registers with incorrect floating point format setting may occasionally result in correct-looking values. It is highly recommended to verify that you have configured the floating point format correctly on your Modbus host system by reading a floating point value from a test value register.