Python is an easy-to-learn, high-level coding language that is ideal for automation. This tutorial will teach you the fundamentals of serial communication with Python. While some coding knowledge is helpful, anyone can learn this material with perseverance.
RS-232 is a key protocol for automating production lines, laboratory equipment, and CNC machines. With knowledge of RS-232 communication, you can easily coordinate and automate repetitive tasks, collect data automatically, and even use modern Python machine learning techniques (PyTorch, TensorFlow) to make the most of your data. Many of the concepts in this tutorial also apply to other network communication protocols, so learning RS-232 will open many doors for you.
This tutorial follows a learning-by-doing approach. It provides you with all the requirements to set up a virtual device on Windows that communicates over a virtual RS-232 port, even if your computer does not have a physical RS-232 port. Feel free to play around with the virtual device to get familiar with automation.
- Copy and modify the provided async/sync communication protocol to your needs for your devices.
- Write your own virtual representation of an arbitrary RS-232 device by analyzing the provided virtual device. This will allow you to work 100% remotely on your automation software while conducting real runs in your workplace or to run testing runs.
- Copy the Python code to a Raspberry Pi that is connected to your equipment and run your devices remotely (OPC-UA).
- And many more!
- download "32bit" 'Virtual Serial Ports Emulator (x32) 1.2.6.788' free download available here: https://eterlogic.com/Products.VSPE.html NOTE: The 64bit version is not for free, just use the 32 bit version. ALTERNATIVELY: Install the SetupVSPE_32_1.3.6.970.zip Consider the specific Licence conditions for this software package: "License grant. "OLENA TER ETERLOGIC SOFTWARE" grants Licensee a non-exclusive and non-transferable license to reproduce, use and redistribute for any purposes the executable code version of the Product, provided any copy must contain all of the original proprietary notices." You can find the full text licence within the SetupVSPE_32_1.3.6.970.zip file.
- Emulate an RS232 "Pair" with ports 'COM14' and 'COM4' > Device > Create > select 'Pair' > 'Weiter' or 'Continue' > select Virtual Serial Port 1 'COM4'; select Virtual Serial Port 2 'COM14' unbox "Emulate Baudrate (optional)" if selected > select 'Fertigstellen' or 'Finish'. You can now find two virtually connected, emulated serial ports in your system. This mimics the data cable between the virtual device and your script during testing and during communication trials.
- Run the virtual_bkp.py file in a separate terminal window You are now able to communicate over port 'COM4' with 'COM14' as if they where real connected ports. The virtual device listens to COM14 and responds according to a real devices documentation. Debug: If your device has already ports 'COM4' or 'COM14' choose other ports. You have to change the called port within your script rs232_communication.py too. Also the virtual device is trying to open 'COM14', change this part of the script virtual_bkp.py too if necessary.
write within bkp_communication.py all predefined functions to pass all the tests in test_bkp_communication.py.
Run the pytest in your terminal with the command "python -m pytest" to get detailed information about your progress.
write a function to monitor all values for voltage, current and status of the device over an arbitrary time.
wrap all your functionality in a self made class.
setup the communication via asynchronous communication (python module 'asyncio')