modbus 2.5

Modbus TCP Server and Client Programs

Modbus Server and Client programs using Python-3

server.py

client.py

Installation:

sudo pip3 install modbus

Usage Examples:

Server:

sudo python3 -m modbus.server …to run server in commandline

For Register Read, the server sends value starting from 1 and incrementing upto 6000. For example, the client wants to read with FuncCode=3, Address=0, and Length=4. Then the server’s reply for values will be 1,2,3,4 for the first read and values will increment for every subsequent read.

For Coil Reads, the server sends back values 85,86… for the required length.

Client:

from modbus.client import client

c = client() …if host = ‘localhost’

c = client(host=’HOSTNAME’) …Change HOSTNAME to Server IP address

c.read() …To read 10 Holding Registers from Address 0

c.read(FC=4, ADR=10, LEN=8) …To read 8 Input Registers from Address 10

c.write(11,22,333,4444) …To write Holding Registers from Address 0

c.write(11,22,333,4444, ADR=10) …To write Holding Registers from Address 10 c.write(11,22, FC=15, ADR=10) …To write Coils from Address 10

Supported Function Codes:

1 = Read Coils or Digital Outputsn

2 = Read Digital Inputsn

3 = Read Holding Registersn

4 = Read Input Registersn

5 = Write Single Coiln

6 = Write Single Registern

15 = Write Coils or Digital Outputsn

16 = Write Holding Registers”)