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The general network topology of a CBus system is very straight forward. It can be wired in any configuration you wish, whether that be a ring, star, or common bus design. You just have to ensure that the correct CBus pink Cat5 network cable is used.

Do I need to use CBus pink CAT5 cable?

The Cat5 UTP cable used for the CBus network has a number of characteristics that help optimize network communications.

  • Cat5 UTP minimizes the coupling of external magnetic fields onto the cable, thus reducing interference on the CBus network.
  • Its electrical characteristics include low capacitance which allows communications over long distances.
  • The twisted pairs inside Cat5 UTP also provide high immunity to noise making it ideal for wiring a CBus network.

Each connection to a CBus unit uses two conductors, that is, two conductors for each positive connection to a CBus unit and two conductors for each negative connection. A connection made with two conductors has several advantages over a connection made with only one conductor:

  • A termination is more secure when it is made with two conductors instead of one.
  • Using two wires for each of the positive and negative rails of the CBus cable decreases the wire’s resistance compared to using one wire for each rail. This then decreases the potential voltage drop that can occur over long lengths of cable.

CBus network communications occur over the standard Cat5 cable, but it is critical to note that CBus networks use wire pairs differently than the standard TCP/IP twisted-pair assignments. The wiring approach also differs for units that have terminals and for those that have RJ-45 ports (e.g., DIN units). However, you will see that the same connections are ultimately made.

When you connect to CBus units that have terminals you will re-arrange the wire pairs at the end of the cable to use “opposite” colors, as follows:

  • Positive supply: Orange and blue wires
  • Negative supply: Orange-white and blue-white wires

Read more: CBus Network Design Considerations

Download CBus Hardware Installation Guide