With the help of Jonas as reviewer I’m one step closer to the solution that was missing in Switch selection. The first version of cancombase is finsihed.

The 5×10 cm pcb fits behind the switches in a double plug socket. The 4 pairs in the CAT cable will be used in the following way:

  1. Connect switch 1 to the miniserver and the backuo system (a post will follow)
  2. Power supply 24V (the selected switches need the 24V and I have decided – since I don’t know better – that a buck is easier than a boost)
  3. + 4. CAN (Since CAN bus does not allow a star topology it’ll be a long bus with a baud rate of around 100kBaud. Of course this has to be checked after installation. Wikipedia indicates that 125 kbit/s allow up to 500 meters of cable. A rough calculation )

A description of the PCB is available here. It’s based on the arduino pro mini. Or an available clone of it.

The gap between the now introduced CAN and the loxone miniserver will be filled (most probably) with a rasperry pi that converts the CAN messages to UDP messages the miniserver is able to read.

Apart from reading switch states (maybe with double-click detection) and writing to feedback LEDs the next version of cancombase will also contain a temperature sensor.

PVI logging

After a long break I’ve started logging the PVIs in my father’s house again. The main reason for reactivating the scripts was that the two PVIs have shown different yield numbers at the end of the day. Further investigation has shown that the internal clock of one of the PVIs was wrong, so at around noon the yield counter was reset, which of course led to different results. Anyway the graphs are online now. Currently the graphs are generated using google charts. Hints for an alternative are welcome.