Modbus Tcp [Oxm] - Baumer OX200 Operating Manual

Baumer
3.3.4

Modbus TCP [OXM]

Modbus TCP is a protocol with a long history that is already supported by many programmable
logic controllers as delivered or can be retrofitted using a software module. Libraries for different
programming languages are available for PC-based systems. The standard is freely available
on the website of the Modbus organisation. To obtain it, visit:
For information regarding the commissioning of Modbus TCP, see
sensor in the PLC [OXM]
Mapping the sensor functionality on the Modbus data model
The functionality of the sensor can be accessed by reading or writing entries in the tables Dis-
crete Inputs, Input Registers and Holding Registers. The following Modbus function codes
(FC) are supported:
Read Discrete Inputs (FC 02)
n
Read Input Registers (FC 04)
n
Read Holding Registers (FC 03)
n
Write Single Holding Register (FC 06)
n
Write Multiple Holding Registers (FC 16)
n
The following 3 FC tables are independent of each other, so that the same address can repres-
ent different functions in each table. Modbus registers are limited to 16 bits. Therefore, when
reading or writing larger values, several registers must be taken into account for the concerned
operation. Reading or writing only part of the specified address ranges is not supported. The
less significant words are saved at the lower address. Example:
Value (UInt32): 0x12345678
n
Register address n: 0x5678
n
Register address n + 1: 0x1234
n
OX200 | V2
[} 70].
Operating Manual
Description
http://www.modbus.org
Modbus TCP: Integrating the
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