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pylon2mqtt

Reads values from Pylontech US2000 batteries and publish to a MQTT broker

Warning

This project has been tested on Pylontech US2000B batteries with firmare version 2.3 and it is working perfectly, but then these batteries were updated to firmware version 3.2 and this code does not work anymore. It looks that Pylontech has done some changes and now the serial port (RS232) does not support Pylontech communication protocol (B.12 data protocol) and it only supports communication by console shell commands.

So it you have Pylontech batteries with modern firmware you should use this other project which uses console commands to get data from Pylontech by RS232. Another option is use RS485 port (CAN bus) if this port is availabe (not my case).

Description

I wanted to read the values of my Pylontech batteries from console port (RS232 protocol) and use them in my HomeAssistant installation (through MQTT). I found two interesting projects that could work for this:

but none of them worked for me, so I did a mix between them, creating this project

The main changes I had to implement were:

  • Start the communication at 1200 baud rate, and then change to 4800 baud rate
  • Change the address field on the commands to value=1. PylonToMQTT project uses 0 as main pack battery and python-pylontech project uses 2 as main pack battery (because of RS485 protocol specification). Neither 0 or 2 worked for me, I received responses with CID2 = 0x90 (address error), but 1 worked for me.
  • Some methods use commands that do not exist in RS232 protocol specification, like method get_version_info() which uses command 0xC1 or method get_barcode() which uses command 0xC2. These methods returns an error frame with CID2 = 0x04 (CID2 invalidation), so I had to search for an alternative command.
  • I have added some new commands (from python-pylontech and some by myself) like get_protocol_version(), get_manufacturer_info() or set_baud_rate()
  • Changed some round() to allow more precission, and change some method like ToAmp() to divide by 10 instead of divide by 100, to get right data in Amps and by hence in watts

How to use

PylontToMQTT project has different ways of use it, from a Docker, into a ESP32, from command line... I have implemented only command line way, so you can only run it with Pyhton. However the only file I have changed is support/pylontech.py, so all other ways (ESP32, Docker...) should work if you replace only this file.

Requirements

Install these libraries: paho-mqtt, pyserial, construct using pip:

pip install pyserial paho-mqtt construct

Run it!

Run it from command line with python using this parameters:

--pylon_port </dev/ttyUSB0>     : The USB port on the raspberry pi (default is /dev/ttyUSB0).  
--rack_name <Main>              : The name used to identify the battery rack. 
--mqtt_host <127.0.0.1>         : The IP or URL of the MQTT Broker, defaults to 127.0.0.1 if unspecified.  
--mqtt_port <1883>              : The port to you to connect to the MQTT Broker, defaults to 1883 if unspecified.  
--mqtt_root <PylonToMQTT>       : The root for your MQTT topics, defaults to PylonToMQTT if unspecified.  
--mqtt_user <username>          : The username to access the MQTT Broker (default is no user).  
--mqtt_pass <password>          : The password to access the MQTT Broker (default is no password).
--publish_rate <5>              : The amount of seconds between updates when in wake mode (default is 5 seconds).

For example:

python3 pylon_to_mqtt.py --pylon_port /dev/ttyUSB0 --rack_name Main --mqtt_host 192.168.2.245 --mqtt_root Pylontech --mqtt_user tomascrespo --mqtt_pass mysecretpassword --publish_rate 5

Run it as a service

I run it as a service in Debian 11 (bullseye). Instructions could be different for other Linux distros.

Create the file pylon2mqtt.service into /etc/systemd/system with contents:

[Unit]
Description=Read values from Pylontech batteries and publish into MQTT

[Service]
User=pi
WorkingDirectory=/home/pi/pylon2mqtt
TimeoutStartSec=infinity
ExecStartPre=/bin/sleep 120
ExecStart=python3 pylon_to_mqtt.py --pylon_port /dev/ttyUSB0 --rack_name Main --mqtt_host localhost --mqtt_root Pylontech --mqtt_user tomascrespo --mqtt_pass mysecretpassword --publish_rate 5
Restart=always

[Install]
WantedBy=multi-user.target

And finally run your service

sudo systemctl daemon-reload
sudo systemctl enable pylon2mqtt
sudo systemctl start pylon2mqtt

Pylontech RS232 protocol specification

Pylontech RS232 protocol specification in this file

@todo

  • Try to change baud rate to greater speed, like 115200
  • Expose a new device in MQTT with average/sum values of different packs, i.e., a device called Pylontech with a field called TotalPower as sum of the watts of each battery pack. This can be get from command 0x42 with info 0xFF