ICP DAS, ZT-2005-C8 User Manual, Version v1.0.1 Page 41
Copyright © 2014 by ICP DAS Co., Ltd. All Rights Reserved.
5.3
Modbus RTU Protocol
The Modbus protocol was originally developed for Modicon controllers by
Modicon Inc. Detailed information related to the Modbus RTU protocol can be
found at http://www.modbus.org for more valuable information.
The Modbus RTU functions of ZT-2005-C8 module are supported as bellow.
Field
1
Field
2
Field
3
Field
4~n
Field
n+1~n+2
Module
Address
Function
Code
Sub
Function
Configuration
Field
CRC16
Function Code
Description
Section
1 (0x01)
Read Coils
5.3.2
2 (0x02)
Read Discrete Inputs
5.3.3
3 (0x03)
Read Multiple Registers
5.3.4
4 (0x04)
Read Multiple Input Registers
5.3.5
5 (0x05)
Write Single Coil
5.3.6
6 (0x06)
Write Single Register
5.3.7
15 (0x0F)
Write Multiple Coils
5.3.8
16 (0x10
Write Multiple Registers
5.3.9
70 (0x46)
Read/Write Module Setting
5.3.10
If the function specified in the message is not supported, then the module
responds as below. Note that the address mapping for the Modbus protocol is
Base 0.
Error Response
Byte
Description
Value
00
Module
Address
1~247
01
Function Code Function Code+0x80
02
Exception Code 02
：
Register not support
03
：
Modbus format invalid
Note: If a CRC mismatch occurs, the module will not respond.
