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 jitter generating device for use in a data communication system. The device has a repeating unit with an input and an output connected in use to receive data from the data communication system and to repeat the data onto the data communication system respectively. A clock signal generator generates a clock signal which is fed to the repeating unit to control the rate at which data is output onto the data communication system. A clock phase (jitter) modulating unit modulates the phase of the clock signal output by the clock signal generator.

Abstract: A communication system comprises a signal carrying medium (8) coupled to a series of end station ports (2-5). The end station ports (2-5) enable respective end stations (21) to transmit signals onto and receive signals from the medium (8). A controller (7) is provided to control the connection of the end stations (21) to the medium (8) via the ports (2-5). Monitors (9-12) are connected to the controller (7) to monitor characteristics of signals generated by the end stations (21) coupled to the ports. The monitors (9-12) are connected in parallel to the medium (8) and supply information relating to the monitored signals to the controller (7) in use. This system allows faulty end stations to be identified and removed from the system.