RS-485 is an industrial bus for connecting sensors over long distances. The total wiring distance is 1km. Sensors can be daisy chained together, or they can be connected to a virtual star using an S-Hub.
In general there is a larger range of sensors available for the RS-485 bus. The RS-485 temperature sensors allow for measurement of more extreme temperatures and to a greater accuracy than the 1-Wire bus sensors for instance. There are also current and voltage measuring sensors available with the RS-485 bus than have no equivalents in the 1-Wire bus family.
The RS-485 bus is a little more complicated to set up than the 1-Wire bus . Each RS-485 sensor needs a unique address (between 65 and 122). The sensors are shipped with a default address which can be changed by jumpers or DIP switches. Additionally, the end of the RS-485 bus needs to be terminated with a resistor which is usually controlled by a switch or jumper in the terminating sensor. Once the RS-485 network has been built, the Poseidon user interface allows the sensor addresses to be named with a more friendly name to identify the sensor.