That project is supposed to provide software for basic communication with nilan heatpumps, containing the CTS-602 control board.
An RS485 adapter, because Nilan is using modbus on top of the physical RS485 layer.
HAZARD NOTE: :warning: If you do not know how to carefully deal with electricity stop here. High voltage danger! No warranties.
The CTS-602 is inside the heatpump, and the correct connectors are on the lower left corner on the circuit board (see picture). The pins on the RS485 connector have the following order:
| Pin 1 | 12 VDC output | |
| Pin 2 | COM1- RS 485 A | Modbus |
| Pin 3 | COM1 - RS 485 B | Modbus |
| Pin 4 | COM2 - RS 485 A | User panel |
| Pin 5 | COM2 - RS 485 B | User panel |
| Pin 6 | Ground | |
As you would find it in the Nilan Modbus Protocol manual.
For the modbus connection you need the pins 2,3,6. In the picture pins two and three are not connected.