Protocol Description; Master-Slave Principle; Transmission Mode (Rtu) - DigiTrace TCONTROL-CONT-03 Anleitung

2.1 Master-Slave principle

2.2 Transmission mode (RTU)

Data format
Communication between a master (e.g. PC) and a slave (e.g. measuring and
control system) using Modbus takes place according to the master-slave
principle, in the form of data request/instruction - response.
Slave 1
The master controls the data exchange, the slaves only have a response
function. They are identified by their device address.
The transmission mode used is the RTU mode (Remote Terminal Unit). Data is
transmitted in binary format (hexadecimal) with 8 bits. The LSB (least
significant bit) is transmitted first. The ASCII operating mode is not supported.
The data format describes the structure of a character transmitted. The
following data format options are available:
Data word
8 bits
8 bits
8 bits
8 bits

2 Protocol description

Master
Slave 2
Parity bit Stop bit
1/2 bit
— 1
even 1
odd 1
— 2
Slave n
Number of
bits
9
10
10
10
7