Data Types And Lengths - IBM Modbus Plus User Manual

Modbus Plus X-Link Driver User's Guide

4.1 Data Types and Lengths

The Modbus Plus Driver supports three X-Link data formats; Bits and
Integers, as well as Floats.
The Modbus Plus protocol does not support floating point. The driver will
truncate any floating point numbers before transmission, and expand the
integer numbers to floating point after retrieval when floating points are
requested.
The type of Modbus Plus command that the driver generates depends on the
address type specified.
The length of the data portion in a command is constrained by the Modbus
Plus protocol. Mappings that are configured with the X-Link reading or
writing the data on the Modbus Plus network should be restricted to a
maximum size of:
Data Type X-Link Access
COIL Read
COIL Write
Registers Read
Registers Write
Global Data Read/Write
48
Maximum Size (bytes)
250
100
250
200
64