JK_UART_to_PYLON_translator

Short Summary: reads JK_BMS via UART and transmits the data via CAN-BUS emulating Pylontech protocol to a Solis battery Storage inverter Inverter sees Volt, Current, SOC and Temp. Script has trivial control-loop to control actual current for charging and discharging. e.g. if the highest cell goes beyond 3.5V max-charge current gets lowered, resulting that the inverter loweres the charging power. Same holds true for the weakest cell. Depending on weakest cell voltage, allowed current-draw gets limited and finally adjusted to zero t protect the lowest cell against over-discharge.

longer story

• Most Important
  • reading JK-BMS via serial UART
  • pushing JK-BMS-data via CANBUS "Pylon" Protocol to a Solis Inverter
• sending some stuff to a MQTT-Broker
• reads a Goodwe-Inverter via HTTP/Sems-Portal
  • will be chnaged against direct IP-connection over next time
• reads directly SMA energy-meter via IP-Socket from the network
• BMS-Features
  • reduces Charging-Power to 0 Ampere of max-cell voltage >3.5V
  • reduces Discharging-Power to 0 Ampaere if min-cell volatge drops below 3.0V
• counteracts if both inverters work against each other
  • if Goodwe charges battery, then Solis is prohibited to discharge
  • if Goodwe discharge battery, then Solis is prohibited to charge
• making good use of multiprocessing-library
• both inverters tend to produce oscialltion. ongoing work to control this via enforcing malually charge/discharge-limts on Solis

major updates

• March 2024
  • added MQTT send/receive
  • counteracting if mqtt-broker is not available on startup
  • added to read SMA entergy-meter to read via socket
• Goodwe added
  • mine very unusual setup inclides a Goodwe EM3648 as well. As I need to avoid that e.g. Goodwe discharges to allow the Solis to charge, I added major control-loops.
  • Important on the Goodwe: Goodwe can be removed from the picture by setting the variable Sems_Flag = False
  • actyally reading the goodwe via HPPS from Sems-Portal. Not ideal. Further work done to read directly via TCP

• added a python-script to candump all messages in human readable format (can_debug.py)

Dear all,

project is in an very early stage. Overall purpose is self-built solar-batterie, using JK-BMS. Older JK-BMS do not support can-bus. This project is aimed to close the gap, by reading battery-stats via UART from JK-BMS and then translating to CAN-BUS using Pylontech Protocol. General speaking this script is massively using below repos from PurpleAlien and Juamiso, combines them into a single script and adds some more control-loop capabilities.

Disclaimer

Initial tests shows it working. Use at own risk. The author is not taking any responsibility for any damage or issue resulting by making use of this project. I am still elaborating if RPI2 is good enough to get the job done. Actually working on a RPI5 which for sure is very much overpowered.

credits

credits go to:

• Juamiso, who developed the CAN-BUS Part
  • https://github.com/juamiso/PYLON_EMU
• PurpleAlien, who developed the JK-UART script
  • https://github.com/PurpleAlien/jk-bms_grafana
• Prasath Premapalan for the can-decoding script
  • https://stackoverflow.com/users/12183162/prasath-premapalan
  • https://stackoverflow.com/questions/58306438/how-to-decode-message-from-a-canbus-iptronik
• by Wenger Florian [email protected] for the SMA-energy-meter

Tested

Initially I tried ti get it runnign with a RPI2. To sloppy and instable. Actually running on a RPI5, which is overpowered. S othe truth seems in the middle...

RPI5          : with wavshare can-hat and usb-serial converter
can-HW        : https://www.waveshare.com/wiki/2-CH_CAN_HAT#CAN_bus:wake
JK BMS        : JK Smart Active Balance BMS BD6A20S10P
Solis inverter: RAI-3K-48ES-5G

install

create venv: apt install python3-pip

python -m venv /home/behn/jk_venv cd /home/behn/jk_venv ./bin/pip3 install cantools pyserial smbus paho.mqtt requests ./bin/pip3 install spidev python-can

create ramdisk

sudo mkdir -p /mnt/ramdisk

(jk_venv) behn@rpi5:~/jk_venv $ cat /etc/fstab .. none /mnt/ramdisk tmpfs nodev,nosuid,noexec,nodiratime,size=96M 0 0

2-channel can-interface

https://www.waveshare.com/2-ch-can-fd-hat.htm

sudo raspi-config Choose Interfacing Options -> SPI -> Yes to enable the SPI interface.

behn@rpi5:~ $ sudo vi /boot/firmware/config.txt

#can hat dtparam=spi=on #dtoverlay=mcp2515-can0,oscillator=12000000,interrupt=25,spimaxfrequency=2000000 dtoverlay=mcp2515-can1,oscillator=16000000,interrupt=25 dtoverlay=mcp2515-can0,oscillator=16000000,interrupt=23 dtoverlay=spi-bcm2835-overlay

behn@rpi5:~ $ dmesg | grep spi [ 3.602609] mcp251x spi0.0 can0: MCP2515 successfully initialized. [ 3.614747] mcp251x spi0.1 can1: MCP2515 successfully initialized.

sysctl start

behn@rpi2:/mnt/sda/etc/systemd/system $ cat jk_pylon.service

# copy this file into /etc/systemd/system
# replace all occurences of /home/behn/jk_pylon with your venv dir
# make the service starting after reboot: systemctl enable jk_pylon
# show status: systemctl show jk_pylon
# stop it: systemctl stop jk_pylon
# if you change this script, reload systemctl: systemctl daemon-reload



[Unit]
Description=Launching JK_pylon converter
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
User=behn
WorkingDirectory=/home/behn//jk_venv
PermissionsStartOnly=true
#Environment=PYTHONPATH=/home/behn/jk_pylon_venv
#ExecStartPre=+/bin/bash -c 'ip link set can0 up type can bitrate 500000'
ExecStartPre=-/usr/sbin/ip link set can0 up type can bitrate 500000
ExecStart=/home/behn/jk_venv/jk_pylon_can.py

[Install]
WantedBy=multi-user.target

testing Basic function blocks first

As the project does include now many different aspects, its easu to break it... Intention of below verification-steps is to test each function standalone! Shall massively help in identifying if something is non-functional

Goodwe

• Mine setup includes both a solis and a goodwe. I need to avoid that Solis e.g. discharges to allow the goodwe charging.

• actually Goodwe gets queried via HTTP Sems-Port. Suboptimal.

• Test Sems-Portal via: sems.py script.

• details at https://github.com/chrgraf/Goodwe_Sems_Portal_Python_Query

• Note: of course the goodwe part can be fully disabled, as the purpose of this repo is Solis/JK-BMS/Pylon

behn@rpi5:~/jk_venv $ ./sems.py
Success

checking SMA-energy Meter reading

You need to make sure to edit the correct serial-number for your enery-meter

behn@rpi5:~/jk_venv $ grep serial sma_em_capture_package.py
   smaemserials=1900203015

behn@rpi5:~/jk_venv $ python sma_em_capture_package.py
Bezug von Grid: -10.0 W

checking UART-connection to JK-BMS

One major comoponent is to read via Serial UART from the BMS. In mine setup the serial adapaper is attached via ttyUSB0. Change as required in the my_read_bms.py script:

Note: do not install serial module. instead install pyserial module: ./bin/pip3 install pyserial

behn@rpi5:~ $ dmesg | grep ttyUSB
[    3.274623] usb 3-2: FTDI USB Serial Device converter now attached to ttyUSB0


behn@rpi5:~/jk_venv $ grep USB0 my_read_bms.py
      bms = serial.Serial('/dev/ttyUSB0')

Executing the script shall result in "True"

behn@rpi5:~/jk_venv $ python my_read_bms.py
query the BMS
USB Serial Adpater Setting:  Serial<id=0x7fff528fe3e0, open=True>(port='/dev/ttyUSB0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=0.2, xonxoff=False, rtscts=False, dsrdtr=False)
Status reading the BMS:  True
return values: [56, 52.28, -12.2, 23.0, 3.266, 3.27, -12.2, True]

canbus

If canbus all does fine, then the canbus dump-tool shall print something like this here

first check if can0 is up and running

sudo ip link show can0 sudo ip link set can0 up type can bitrate 500000

behn@rpi5:~/jk_venv $ ./can_debug.py
[message('Network_alive_msg', 0x305, False, 8, None), message('Battery_Manufacturer', 0x35e, False, 8, None), message('Battery_Request', 0x35c, False, 2, {None: 'Bit 5 is designed for inverter allows battery to shut down, and able to wake battery up to charge it.Bit 4 is designed for inverter doesn`t want battery to shut down, able to charge battery before shut down to avoid low energy.'}), message('Battery_actual_values_UIt', 0x356, False, 6, None), message('Battery_SoC_SoH', 0x355, False, 4, None), message('Battery_limits', 0x351, False, 8, None), message('Battery_Error_Warnings', 0x359, False, 7, None)]
{'Alive_packet': 0}
{'SoC': 56, 'SoH': 100}
{'Manufaturer_string': 336337852752}
{'Full_charge_req': 0, 'Force_charge_req_II': 0, 'Force_charge_req_I': 0, 'Discharge_enable': 1, 'Charge_enable': 1}
{'Battery_voltage': 52.24, 'Battery_current': -14.8, 'Battery_temperature': 23.0}
{'Battery_charge_voltage': 56.0, 'Battery_charge_current_limit': 0.0, 'Battery_discharge_current_limit': 60.0, 'Battery_discharge_voltage': 51.0}
{'Overvoltage_ERR': 0, 'Undervoltage_ERR': 0, 'Overtemperature_ERR': 0, 'Undertemperature_ERR': 0, 'Overcurrent_discharge_ERR': 0, 'Charge_overcurrent_ERR': 0, 'System_Error': 0, 'voltage_high_WARN': 0, 'voltage_low_WARN': 0, 'Temperature_high_WARN': 0, 'Temperature_low_WARN': 0, 'Discharge_current_high_WARN': 0, 'Charge_current_high_WARN': 0, 'Internal_Error_WARN': 0, 'Module_numbers': 16}
{'Alive_packet': 0}

Install

I will add more info over time. But its a good idea to clone https://github.com/juamiso/PYLON_EMU to get hold of the required pylon_CAN_210124.dbc file. After having all python libs installed, just execute the script delivered via this repo

behn@rpi5:~/jk_venv $ ./jk_pylon_can.py
Logging to file: /mnt/ramdisk/jk_pylon.log
logging to console is disabled
 -enable logging to console  by setting variable log_to_console=True
Connected to MQTT Broker!

python serial library

I gave up on trying to use venv and pip-install serial. Whenever I used venv or serial-lib via pip-install, the UART to JK-BMS failed

I solved it by making sure to install serial-library via:

sudo apt-get install python3-serial
Note: For me, trying to use pip install serial resulted in UART to BMS failing!

making the script autostart as a service

If the script stops, that the inverter does not have a valid can-bus coomunication and hence all charging/discharging is stopped by the inverter. Making the script a service, even reloads the scripts in case e.g. it was killed..

some good reading: https://medium.com/@benmorel/creating-a-linux-service-with-systemd-611b5c8b91d6

systemd script

make sure to adopt your user-id in below script!

behn@rpi5:~/jk_venv $ cat /etc/systemd/system/jk_pylon.service

# copy this file into /etc/systemd/system
# replace all occurences of /home/behn/jk_pylon with your venv dir
# make the service starting after reboot: systemctl enable jk_pylon
# show status: systemctl show jk_pylon
# stop it: systemctl stop jk_pylon
# if you change this script, reload systemctl: systemctl daemon-reload



[Unit]
Description=Launching JK_pylon converter
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
User=<>                                                       # <<<< enter your user-idf here!
WorkingDirectory=/home/behn//jk_venv
PermissionsStartOnly=true
#Environment=PYTHONPATH=/home/behn/jk_pylon_venv
#ExecStartPre=+/bin/bash -c 'ip link set can0 up type can bitrate 500000'
ExecStartPre=-/usr/sbin/ip link set can0 up type can bitrate 500000
ExecStart=/home/behn/jk_venv/jk_pylon_can.py

[Install]
WantedBy=multi-user.target

autostarting and enabling the systemd script

Once added the script execute:

$ systemctl start jk_pylon

And automatically get it to start on boot:

$ systemctl enable jk_pylon

stopping the script

$ systemctl stop jk_pylon

cabling

Please find the connection towards JK-BMS via UART <> RPI2 via USB serial device. Make sure the USB-serial converter allows to Jumper for 3.3V!

Features

Reads Batt_voltage, current, SOC, temperature from the JK_BMS and sends it to the Inverter with Pylon Protocol. The original script was translating the derived Current incorrectly. This is now corrected and now correct current gets reported. A very much simple charge-control loop got added. e.g. if either the cell with highest voltage or the cell with lowest voltage is crossing a treshhold, the script controls the inverter to modify charge or drawn current:

Battery_charge_current_limit_default

min_volt set the limit

if (min_volt>=3.3): Battery_discharge_current_limit = 60 elif (min_volt>=3.1): Battery_discharge_current_limit = 50 elif (min_volt>=3.0): Battery_discharge_current_limit = 30 elif (min_volt>=2.9): Battery_discharge_current_limit = 10 elif (min_volt<2.9): Battery_discharge_current_limit = 0 else: Battery_discharge_current_limit = Battery_discharge_current_limit_default

if (not oscillation): # max_volt the limit if (max_volt>=3.55): Battery_charge_current_limit = 0 elif (max_volt>=3.50): Battery_charge_current_limit = 2 elif (max_volt>=3.47): Battery_charge_current_limit = 15 elif (max_volt>=3.45): Battery_charge_current_limit = 30 elif (max_volt>=3.0): Battery_charge_current_limit = 60 elif (max_volt>=2.7): Battery_charge_current_limit = 30

Another item I am looking into is related to mine solis-inverter. Sometimes its control-loop fails to adjust reasonable amount to charge battery, resulting in either charging thsat high that in addition to excesssolar-power, power from grid id taken. This oscialltion-counteract routine is in a very early stage though..

thanks

BELOW IS NOT WORKING

trying to use VENV with systemd fails to open the ttyUSB port

running the script in python venv

I am using numpy lib in mine script, which does not have a native ubuntu repo. I decided to go via python venv to run the script.

preparing python venv

sudo apt update && sudo apt upgrade -y
sudo apt install python3-pip -y
sudo apt install build-essential libssl-dev libffi-dev python3-dev
sudo apt install python3-venv -y

as a next create the venv This creates a directory jk_pylon

python -m venv jk_pylon_venv

This article says itsa bad idea to put your project-files into same directory which holds your venv. So lets keep the venv-directory jk_pylon_venv and the project-dir jk_pylon seperated.

now copy all required files into this directory

cp alien_master1.py pylon_CAN_210124.dbc requirements.txt ./jk_pylon/

activating the venv

prompt shall look like this after executing the activate : (jk_pylon)..:~/jk_pylon $

$ source jk_pylon_venv/bin/activate

install all dependencis

(jk_pylon_venv) behn@rpi2:~ $ pwd
/home/behn
(jk_pylon_venv) behn@rpi2:~ $ pip3 install -r ./jk_pylon/requirements.txt

finally run the script

above source "source jk_pylon_venv/bin/activate" should have chnaged your prompt, indicating (jk_pylon_venv)

# change into the projct directory, required to find the pylon_CAN_210124.dbc file
(jk_pylon_venv) behn@rpi2:~ $ cd jk_pylon
# launch the script
(jk_pylon_venv) behn@rpi2:~/jk_pylon $ ./jk_pylon_can.py
Carrying out cyclic tests with socketcan interface
Starting to send a message every 1s
cellcount= 16
[]

systemd script - not this fails to open the ttyUSB, so do not use..

root@rpi2:/etc/systemd/system# cat jk_pylon.service
# copy this file into /etc/systemd/system
# replace all occurences of /home/behn/jk_pylon with your venv dir
# make the service starting after reboot: systemctl enable jk_pylon
# show status: systemctl show jk_pylon
# stop it: systemctl stop jk_pylon
# id you chnage this scrip[t, reload systemctl: systemctl daemon-reload



[Unit]
Description=Launching JK_pylon converter
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
#User=root
User=behn
Group=dialout
WorkingDirectory=/home/behn/jk_pylon
#ExecStart=/home/behn/jk_pylon_venv/bin/python jk_pylon_can.py
ExecStart=/home/behn/jk_pylon_venv/bin/python -m jk_pylon_can
StandardOutput=tty
TTYPath=/dev/pts/1

[Install]
WantedBy=multi-user.target