The wired portion of the uberbus is based on a RS485 bus. This Bus needs at least a twisted pair of wires for data transmission and an additional wire for ground potential.

To connect the different nodes with each other and supply them with energy standard CAT5 Ethernet patch cables are used. These cables offer 4 pairs of wires. Three pairs are chosen to supply the nodes with energy while the fourth pair is for data transmission.

The pin assignment is as following:

TODO: insert pin assignment.

A uberbus node which connects to the bus has either one or two RJ45 jacks, If only one jack is available the node has to be connected using a bus adapter. Suitable adapters are ISDN bus adapter like … and … from Reichelt.

If the node has a second jack it is possible to use one of the jacks as the input jack and the other jack as output jack. The node can also be connected like a node with only one jack.

TODO: insert diagram of the topology here.

Termination and cable length

Usually a RS485 bus consists of a single cable with two ends and the nodes attached directly to it. This cable is usually terminated at both ends using termination resistors.

TODO: insert diagram

With the uberbus some nodes might be attached using stubs. These are connections which lead away from the main cable and are not terminated. This is possible as every uberbus device uses special RS485 transceivers which have an artificial limit of their speed. This allows a reasonable amount of subs to be present at the bus.

First estimate: A single stub should not be longer than 5 meters. All stubs together should not be longer than 50 meters. TODO: insert calculations

  • uberbus/physical.txt
  • Last modified: 2021/04/18 12:35
  • (external edit)