There are two more controllers attached to the CAN bus: the 1 wire controller and the ventilator controller.
The 1 Wire ControllerThe 1 wire controller contains interfaces for two 1 wire buses. I decided to connect the temperature sensors on the first 1 wire bus, and the humidity sensors on the second. The reason why I have a 1 wire controler is that 1 wire sensors are widely available. In theory they can even drive their power from the signal line. But I am not using the 1 wire sensors in that way (I could though). Sensors with CAN interfaces are less available, they are larger, they need power supply, and they are more expensive.
The Ventilator ControllerThe ventilator controller uses two S202 S12 solid state relais to apply 220V to the ventilators to turn them on and off.
Final WordsWhy did I choose CAN and 1 wire instead of using zigbee, FS20, or something similar with wireless? There are several reasons:
- Zigbee, FS20 or anything else with wireless were not very popular or available during the time I designed the control system. I am not aware that there are sensors having zigbee (maybe there are, but I did not look), and if yes, I can imagine they are expensive.
- I am a little suspicious about the reliability of radio controlled systems. E.g. the operating range of these radio controlled systems is rather limited. Probably I would have needed repeaters all over the house. And what if the neighbor uses the same FS20 system. So when he opens his garage door with FS20, he triggers my ventilators as well?
- All the devices need power supply anyway, so there must be a cable which supplies power somehow. In my system the devices draw power from the CAN cable.