AN INTERFACE CIRCUIT HAVING A DATA BUS INTERFACE

摘要

There is provided an interface circuit, a network switch or network device coupler incorporating the interface circuit, and a network incorporating the network switch or network device. The interface circuit has a data bus interface (7) for connecting a data bus to either a first device (6) that communicates in a first signalling protocol or a second device (6) that communicates in a second signalling protocol. The data bus has two bus conductors that provide combined power and data. A voltage source (12) powers the data bus. The voltage source (12) is connected to the data bus via a reactance (10) and then a first resistance (4) connected in series. An output of a transmitter (13) is connected via a second resistance (3) to a point between the reactance (10) and the first resistance, to modulate the data bus.

主权项

1. An interface circuit comprising a data bus interface and a transmitter and receiver for sending and receiving data via the data bus interface, wherein:
the data bus interface comprises two bus conductors consisting of a positive polarity conductor and a negative polarity conductor that provide combined power and data, and connector terminals for connecting the two bus conductors to one of a first device that communicates in a first signalling protocol and a second device that communicates in a second signalling protocol, the first and second signalling protocols being different protocols to one another, wherein the interface circuit is configured to select between the first signalling protocol and the second signalling protocol depending on which one of the first and second devices are connected via the connector terminals; and the interface circuit further comprises a voltage source for powering the two bus conductors, the voltage source being connected to the two bus conductors via a reactance and then a first resistance connected in series, wherein an output of the transmitter is connected via a second resistance to a point between the reactance and the first resistance, to modulate the voltage between the two bus conductors.