This repo has a few different implementations and tools for communicating with EP Solar Tracer charge controllers. This has been tested with Tracer model 3210A, but should work with any EP Solar Tracer model that uses Modbus RS485 and MT50 displays.
There are 2 different Modbus libraries for Python that work well, pymodbus and minimalmodbus. Pymodbus is better to use because it has more options. libmodbus is a library for C that others have used with Raspberry Pis.
Because the rs485 converter to USB port implementation for the Raspberry Pi relies on version specific drivers, the Arduino implementation might be more future proof.
This works with a USB to RS485 converter (ch340T chip model).
I was not able to get this to work with the manufacturer's recommended cable (Model: CC-USB-RS485-150U) because the EXAR USB drivers would not work with this version of the Raspberry Pi. A number of other people have successfullly used that cable and EXAR drivers with earlier Raspberry Pi models. (EXAR drivers: https://www.exar.com/design-tools/software-drivers)
RJ45 blue => b
RJ45 green => a
- sudo apt-get update
- sudo apt-get dist-upgrade
- sudo apt-get install git
- sudo apt-get install python-pip
- pip install pymodbus
- pip install serial
- git clone https://github.com/alexnathanson/EPSolar_Tracer.git
- pip install numpy
- pip install pandas
- Lsusb
- dmesg
- ls /dev/* | grep XRUSB
- python -m serial.tools.list_ports
- dmesg /dev/ | grep tty
- sudo cat /proc/tty/driver/serial
If you're trying to use the EXAR driver set the port to the right permissions.
- sudo chmod 777 /dev/ttyXRUSB0
This lists a few simple solutions and some trouble shooting steps:
The issue I ran in to was that the modules my program needed to import were tied to the 'pi' user. To get around this I had to change the user in the rc.local file before running the script. (This solution came from https://raspberrypi.stackexchange.com/questions/78141/python-script-fails-with-importerror-when-run-from-rc-local) You might also need to mess with the file permissions to make the script executable and if you're piping your output to another file you may need to make that file writable.
- sudo -H -u pi python [my script]
This method uses a Max485 and a 5v to 3.3v level shifter. I have not realized this version, but it should be doable if you need to free up USB ports for whatever reason.
Some GPIO resources
- https://learn.sparkfun.com/tutorials/txb0104-level-shifter-hookup-guide?_ga=2.223672476.663927220.1545672234-707983221.1543353897
- https://spellfoundry.com/2016/05/29/configuring-gpio-serial-port-raspbian-jessie-including-pi-3/
- https://www.instructables.com/id/How-to-Use-Modbus-With-Raspberry-Pi/
- https://doc.homegear.eu/data/homegear-homematicwired/configuration.html#config-rs485-serial
- https://www.raspberrypi-spy.co.uk/2018/09/using-a-level-shifter-with-the-raspberry-pi-gpio/
- https://www.raspberrypi.org/documentation/configuration/uart.md
This works well. It's a pretty easy implementation. I'm using software serial to free up the USB port for serial communication with a computer or whatever you want. In the future I may build it out as a library.
You can monitor the serial port from the Arduino IDE or serialTest.py (serialTest.py is a simple alternative if you can't get the Tracer to communicate directly with the Raspberry Pi)
This uses the Modbus Master library. https://github.com/4-20ma/ModbusMaster
This is the simplest implementation. It uses the manufacturer recommended RS485 to USB cable (Model: CC-USB-RS485-150U). This also worked with ch340T model.
In device manager right-click on the port and select properties. In the port settings tab make sure RS-485 is checked and the BPS is set to 115200. The other settings I used were databits = 8, parity= None, stopbits = 1
Both minimalmodbus and pymodbus libraries work well with my PC.
https://github.com/kasbert/epsolar-tracer
http://www.solarpoweredhome.co.uk/
https://medium.com/@jcrbcn/installing-the-exar-usb-driver-on-the-raspberrypi-for-teknic-sc-hub-39de533f0502
Tracer charge controller https://www.epsolarpv.com/product/3.html
Tracer Modbus Protocol http://www.solar-elektro.cz/data/dokumenty/1733_modbus_protocol.pdf