Computer network adapted for industrial environments

Abstract

A network for connecting a plurality of devices and the components used in constructing the network. The network includes at least one fan-out device for connecting the devices to each other. The fan-out device includes a controller, a top port and a plurality of downstream ports. The controller monitors messages received by the ports and generates messages that are sent via the ports. The network also includes a plurality of network cables, one per port. The network preferably utilizes a cabling system that includes twisted pairs for communicating the messages via the Ethernet protocol and power conductors for distributing power to the various network devices. The fan-out device includes one power component associated with each of the ports. Each power component provides connections between the power lines in the network capble and the ports of the fan-out device. The power components are used to power the devices on the network and to monitor the power lines for problems. Switching circuitry in the power components allows the fan-out device to isolate cable runs connected thereto that have shorts or other problems. The fan-out device preferably stores a device identification number that the controller transmits on all of the ports in response to a message received on one of the downstream ports. The controller also generates a signal on the top port that causes any device connected to the fan-out device via the top port to ignore the message. One embodiment of the fan-out device provides a hub that is transparent to Ethernet protocols while not introducing the jitter into the signals associated with the re-transmission and synchronization functions performed by conventional hubs.