Before compiling code, make sure you have the correct path to your MODBUS adapter. On my Mac it was /dev/tty.usbserial-DO001BL8 Also, make sure you have libmodbus installed.

Using homebrew...

brew update
brew install libmodbus

g++ `pkg-config --cflags --libs libmodbus` suresine.cpp -o suresine && chmod +x suresine

./suresign

The light will turn red on the inverter signaling the configuration changed.

1. You will now need to restart the invert for the change to take effect.
2. Disconnect DC power to the inverter.
3. Make sure the DIP #2 is up/on. This signals to the inverter you want to use your custom value
4. Add power back to the invert
5. Optionally, run the program again to see that the changes were saved in your registers

• Morningstar official documentation for changing LVD and LVR: http://support.morningstarcorp.com/wp-content/uploads/2014/07/SI.APP_.LVD-Adjustment.02.EN_.pdf
• Morningstar official documentation for the register settings: http://support.morningstarcorp.com/wp-content/uploads/2014/07/SI300.APP_.Modbus.EN_.03.pdf:q
• libmodbus documentation: http://libmodbus.org/docs/v3.1.4/modbus_write_register.html
• Example blog showing example of how to connect to MorningStar SureSine using libmodbus on Mac/Linux: https://westyd1982.wordpress.com/2010/03/26/linux-and-mac-os-x-software-to-read-data-from-the-sunsaver-mppt-using-modbus/