Modbus Communication Protocol - EAS ELECTRIC ECG145CM Manual De Instrucciones

ECG145CM Touch screen controller

Modbus communication protocol

Overview
1.1
A. Use RTU type of ModBus protocol
B. Use R485 multi point bus master-slave structure, asynchronous half duplex mode, The data
length of 8 bits no parity, baud rate is 9600bps. (8,N,1 for RTU)
1.2 Character structure (8, N, 1)
Start
0 1 2 3 4 5 6 7
bit
1.3 MODBUS Data Frames
Additional address
1.4 MODBUS Data Encoding
For example: send data 0x1234, first send 0x12, then 0x34.
1.5 MODBUS Address
Coils(R)
Base address: 0x0000
Operation address = Base address + Relative address
Relative addr Data name
0# Indoor unit
0x00...0x0F
Coil status
8-data bits
10-bits character frame
（PDU）
Function code
（ADU）
Note
0
B0 Fan mode
B1 Dehumidify
mode
B2 Heating mode
30
Stop
bit
Data
Error check
1: Valid, 0: Invalid
1: Valid, 0: Invalid
1: Valid, 0: Invalid
V.1