A remote Input/Output rack is one that is located away from the processor module. To communicate with each other, a specialized communications network is used.
Each remote rack must have a station number to distinguish itself from each other. The remote racks are connected to the local rack through a communications module and cables connect the racks together.
Coaxial or Fiber Optic cables can be used and/or wireless communication. The PLC uses a system called “addressing” to communicate with each of the racks.
Each rack has an “address” (this is why each rack must have its own station number) that the PLC uses to direct its messages.