Modbus (Rtu) Communication; Overview Of Modbus (Rtu) - Weidmuller Power Monitor Handbuch

Communications
9.4

MODBUS (RTU) communication

9.4.1

Overview of MODBUS (RTU)

8-bit binary data in command is transmitted as it is.
Data format Start bit
Data bit
Parity
Stop bit
Error detection
Data interval
Message configuration
RTU mode is configured to start after idle time processing of more than 3.5 character transmissions and end
after idle time processing of more than 3.5 character transmissions.
3.5 idle
characters address
Master judges the transmission complete after no command for 4-characters idle time and processes the
command.
Transmission speed and judgment time to complete transmission
Transmission speed (bps)
38400
19200
9600
4800
2400
1200
1435710000/01/05.13
1 bit
8 bits (fixed)
No parity, even parity, odd parity selectable
1-bit, 2-bit selectable
CRC-16 (Cyclic Redundancy Check)
3.5 character transmission time or less
Slave Function
code
8-bit 8-bit
Judgment time to complete (ms)
about 1
about 2
about 4
about 8
about 16
about 32
Error check
Data
CRC-16
xx bits 16-bit
3.5 idle
characters
79