E2658-C2H4
Rev 12.03.2021
Modbus RTU Communication
RS485 communication interface
Communication parameters
Modbus holding registers
Register addresses are shown 0-based, Address in hexadecimal, Reg in decimal format.
Modbus holding register numbers MHR are shown in the decimal 1-based format and may
be addressed either from 00001 or 40001 base.
16
Databits: 8
Parity: none / odd / even
Stop bits: 1 or 2
Protocol: Modbus RTU
Supported Modbus functions:
03 – Read multiple registers
06 – Write a single register
Parameter
Permitted values
Default
Supported baud rates 1200, 2400, 4800, 9600, 19200, 38400, 57600
9600
Data bits
8
8
Parity
none / odd / even
none
Stop bits
1, 2
1
Protocol
Modbus RTU
Modbus functions
03 - Read multiple registers
06 - Write a single register
Error codes
01 – Illegal function
02 – Illegal data address
03 – Illegal data value
04 – Slave device failure
(details of last error 04 can be read from register 0x0008)
Address Reg / MHR RW Description
Supported values (dec)
Default
0x0001
1 / 40002 R Hardware version
-
0x0002
2 / 40003 R Software version
-
0x0003
3 / 40004 R Product serial number
1...65535
-
0x0004
4 / 40005 RW Slave ID (net address) *
1...247 **
1
0x0005
5 / 40006 RW Baud rate *
1200, 2400, 4800, 9600,
19200, 38400, 57600
9600
