Abstract: A method of connecting a new end station to a ring communication system for connecting a number of end stations is constituted by the steps of: i) sensing an attempt by the new end station to attach to the ring; ii) determining whether there is a single end station only existing on the ring; and, iiia) if it is determined that there is more than one end station on the ring, allowing the new end station to attach to the ring and maintaining the ring communication configuration; or b) if it is determined that there is a single end station only on the ring, breaking the ring configuration and setting up two separate communication paths between the new end station and the existing end station.

Abstract: A method and apparatus for impedance matching a transmitter to a transmission medium of a communication system during normal operation of the system. The method comprises feeding signals from the transmitter to the transmission medium through a variable impedance; monitoring the potential upstream and downstream of the variable impedance; generating a control signal related to the monitored potentials; and adjusting the impedance of the variable impedance in accordance with the control signal until the monitored potentials satisfy matching conditions in which the transmitter is impedance matched to the transmission medium.