The piece of hardware I’ve been waiting for arrived today. As can be seen, it’s just a four-wire cable, with some circuitry for galvanic isolation in one end and a D-sub with an USB-plug for power supply.

The image shows how it looked like before I started working on it. Today the curcuit board is mounted inside the heat pump, and the D-sub is located at the computer in the other end of the house, connected with the cable I’ve previously mentioned.

The initial tests looks promising; now I’ve got to set up the logging properly and then write the applicationI’ve been thinking about that will parse the data and present it as diagrams. I know there’s an application that does this already, but I’ve got some additional things I want it to do.