pyModbusTCP - the easy way to a Modbus TCP server with Python 

How did you do that?

Can you share your project ?

Brother, I have a query. The data we send using DataBank.set_words(5 , [4]) get recorded in holding register as well as input register. Is there a way to send the data to just the input register?

@Johannes 4Linux

Yes Siemens S7-300

Thank you. Good to know. I haven't use signed numbers with this module.

Witch "except:" You catch every exception. If you have a typo in the try area, the exception will be also triggered. If you change my code to "except KeyboardInterrupt::" you will only catch the Interrupt generated when you press CTRL+C. To throw an exception you can use "raise [exception]", e.g. "raise ValueError" in a try area.

Hi bobby, yes, of course, if the driver offers the interfaces you need, it is better to use the already implemented (and tested) drivers interface. Maybe a good example for this is the i2c lib, which uses ioctl calls to access the i2c bus. Here is a link: github.com/amaork/libi2c I hope, this will help you.

@@johannes4gnu_linux96 Thank you for answering my question, always good when people help each other! Wish you all the best!

Thank you. I haven't make a video about serial communication with Modbus, but there should be some available on youtube. pymodbus is a python module, supporting all kinds of Modbus communications including RS485. But compared to pymodbustcp it is more complicated. pymodbustcp only supports Modbus communication over Ethernet.

Johannes 4Linux i see, thanks. İf i have a question about pymodbus, can you help me?

@@johannes4gnu_linux96 I was succeed by using address 0.0.0.0 at Server side.

I got the same error which says [Errno 11001] getaddrinfo failed because of c.open(). I cant fix it what can i do

@@johannes4gnu_linux96 no i used windows, but my host was in onather place, but they didnt open the port that i used. That was the problem but we solved it thanks a lot for your explanation

@@rmatveev thanks! I was looking for this answer!

@@johannes4gnu_linux96 Hey, danke für deine Antwort. Habe es jetzt am laufen. Es gab ein Problem mit der IP-Adresse des Servers. Vielen Dank dir !

@@michaelbraunlein7500 zet true, unt veda deine inkeslagen direct am laufen. Nein es brinkeswort valen as TCP Server!

Thank you. Well it depends what PLC you are using. Assuming you use a Simatic PLC, there are Functional Blocks available, if I remember correctly, ModbusTcpClient and ModbusTcpServer. You can use them to connect to your server. Then you can start adding a database to your Python program, e.g. sqlite. But here I maybe would do it the over way round. The PLC, which provides the data wolud be the server and the Python program would be the client. The PLC puts the measurement data in the Modbus registers and your python program reads them out every given time and stores them in the database.

@@johannes4gnu_linux96 Ok I understand. Yes, I am using a Simatic S7-300. I already have my database in my Django web project, I am using postgreSQL. But I am somewhat complicated with this, how do I communicate the PLC with this web project through modbus? Thanks in advance

@@leonelrondon8037 hey! hope u doing well, i wanna ask u if u've got the answer u need for ur question...ig i'm facing a similar problem, in fact i'm working on a Simatic PLC and i'm trying to read data from the registers by coding and running a ros node in python that connects to this plc using modbus, do u have any idea how this can be done? i'd apreciate it ^^

@@Blue-xv9rg hey! First of all, what PLC are you using? The one I used is not compatible with PYMODBUSTCP, therefore the information in this video did not work for me, I needed to communicate with it through a serial port, for this I used an OPC server, called IBH Softec, which is compatible with PLC Siemens, then in python I used the python opc library, investigate it and according to your requirements you adapt it to what you want, the Python opc library is simple and on the net there are many videos to connect PLC with python through this library, there are also a variety of opc servers, but in my case I used the one I tell you about. I hope to help you, regards.

OK. Do you get a response when trying to ping your device? Some Modbus devices I know have a Webserver integrated over which you can configure them. Does your device have one and can you access it? Have you douplechecked Modbus TCP is enabled on your device?

Assuming you are using a debian based distro like Ubuntu, you need python, the python package manager pip and pymodbustcp. python should already come preinstalled, but the following command will install the needed packages: sudo apt install python3 python3-pip To install pymodbustcp use: sudo pip install pymodbustcp And that's it. After this you can follow the instructions in my video.

Search for "Briged Network" if you wnat to conenct your VM to the outside world or for "Internal Network" if you want to connect various VMs.

@@johannes4gnu_linux96 So in oyur example the ModbusServer function mimick the slave (PLC) and the ModbusClient mimick the Master. Am I right? And What if I wanna connect to the PLC S7-1200 from the kali VM. How I would do that using python?

@@ikbelhammami5525 As far as I know, you can program a S7-1200 to be a Modbus Server or Client. It should support both functions. If the PLC offers data to fetch for the VM, I would setup the PLC as Server a.k. Master. For the VM setup. If you are using a bridged network configuration, the VM will actually use your WiFi or Ethernet interface and will get an IP address assigned by your router. Then you can access the PLC just as you would on a normal PC. Just replace the 127.0.0.1 with your IP address and it should work.