Suitable for building an optical star bus topology between devices with an electrical interface according to RS-232, RS-422, RS-485 or Profibus, the fiber optic Multi-Standard Star-Coupler helps secure data transfer and removes interference between the host workstations. One active star-coupler and a number of firm's standard interfaces corresponding to the number of channels are required for an application. Its 19-in. mounting shelf design allows for rack mounting or stand-alone usage. The transmit/receive modules, each containing three I/O channels, are cascadable to a total of 18 modules, thereby providing a maximum number of 54 channels.