A RS485 bus needs a 120ohm resistor placed at each end of the cable run. Software switched terminating resistor This circuit works well for digitally switching in a terminating resistor:
Category: RS485
.RS485 General
Speed & Cable Lengths Max bus length 1200m (at 100kbps) Max transmission rate 10Mbits (up to 12m) Maximum Number Of Nodes RS485 is specified as max 32 devices connected to the bus, although some drivers allow more (2x or 4x)
CAN vs RS485
CAN (Controller Area Network) and RS485 are both popular standards in fieldbus systems. RS485 only addresses layer 1 (the physical layer) CAN also adds layer 2 (the data link layer) in the OSI model. Both are based on multiple nodes connected to a shared serial bus with one or more acting as a master being possible. […]