CODEWITHSUNDEEP
pythonmodbuspymodbus
ellinagreek
ellinagreek

Reputation: 13

How we can generate traffic within the PyModbus library?

I want to generate some Modbus traffic, but I can't find any examples. In other words, I want to create a Modbus Simulator.

Upvotes: 1

Views: 222

Answers (1)

Marcos G.
Marcos G.

Reputation: 3506

A good start would be to look at the examples folder.

An easy way to have something up and running is to follow these steps, assuming you have pymodbus installed:

  1. Download and run the syncronous_server.py example from the command line

  2. Download and run on a different command window the syncronous_client.py example.

You are done, from the output of both command lines you will be able to see the Modbus transactions that took place.

If you want to have a continuous stream of Modbus exchanges you can just modify the client to loop somewhere, for instance:

while True:
    rr = client.read_holding_registers(1, 1, unit=UNIT)
    time.sleep(1)

will keep reading a holding register about once every second.

There is no need to change anything on the server, it will be always listening until you kill it with Ctrl+C

Nothing will prevent you from having a different computer for the server and client as long as both are connected to the same network and you modify the client to point to the server address. In particular (line 70 on the example):

client = ModbusClient('localhost', port=5020)

Change localhost to your server's IP address, maybe something like 192.168.x.y.

In case you are not aware there are many alternatives to pymodbus to generate Modbus traffic. Modpoll is a classic, but you can also look at qModMaster.

Upvotes: 1

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