Current Loop Sensor Interface Using a Terminated Symmetrical Physical Layer

摘要

A sensor system or a sensor bus comprises a plurality of sensors coupled together by a bus to a controller for sensing physical parameters and responding to changes of the physical parameters. The bus comprises a two wire bus, with a first wire and a second wire, configured to communicate supply signals to the plurality of sensors and data communication signals generated by current modulate signals from the plurality of sensors or the controller. The plurality of sensors and the controller comprise variable current sources. The variable current sources of the sensors generate data communication signals in a first frequency range, while the variable currents sources of the controller and sensors regulate the supply signals from the bus in a different frequency range. A termination network having termination, dividers at both ends of the bus, match the load impedances and the line impedances of the bus within the first frequency range, which is about five to ten times larger than the second frequency range.

主权项

1. A sensor bus system, comprising:
a two wire communication bus, comprising a first wire and a second wire, coupled to a plurality of sensors and a control unit, wherein the two wire communication bus is configured to communicate, in a first frequency range, data communication signals between the plurality of sensors and the control unit, and supply signals from the control unit in a second frequency range that is different than the first frequency range; a termination network configured to match a load impedance and a line impedance on both sides of the first wire and the second wire of the two wire communication bus in the first frequency range of the communication signals; and a plurality of current sources, respectively corresponding to the plurality of sensors, configured to generate the data communication signals in the first frequency range, and regulate voltages detected at the plurality of sensors in the second frequency range.