Modbus Registers; B.1 Modbus Registers - Siemens SICAM Manual

Modbus Registers

B.1 Modbus Registers

B.1

Modbus Registers

Modbus is a field bus which is used to exchange data between programmable logic controllers (PLCs) and
other devices. The communication protocol is based on the master/slave system over a serial line (RS485).
The Modbus master requests data from the slaves which are connected to the bus. The slaves answer to the
request from the master. The device works as Modbus Slave and supports communication via RS485. Regard-
less of the transmission mode, the communication cycle and contents remain the same. The message frame
contains the following format:
•
Device address
•
Function code
•
8-bit data bytes
•
Error checking
The following Modbus data models are supported:
•
Bit type data
– Discrete input
– Coil
•
Register-type data
– Input register
– Holding register
94 SICAM, Feeder Condition Monitor, Manual
E50417-H8940-C580-A4, Edition 03.2019