HART CHANNEL INTERFACE COMPONENT INCLUDING REDUNDANCY

摘要

A channel interface component including redundancy within a control system with highway addressable remote transfer (HART) channels is provided. In one embodiment, a circuit includes: at least two highway addressable remote transfer (HART) channels, each HART channel including an input terminal and an output terminal configured to connect with a HART device via a current loop; an channel interface component coupled to each HART channel that is configured to support HART protocol signals for communications with the HART device, wherein the channel interface component includes a suicide relay switch for connecting or disconnecting each HART channel from the HART device; and a programmable logic device coupled to the channel interface component that is configured to perform modulation and demodulation of HART protocol signals for communications with the HART device.

主权项

1. A circuit for providing redundant highway addressable remote transfer (HART) channels, comprising:
a redundant pair of channel interface components, each having an input terminal and an output terminal configured to connect with a common HART device, wherein each channel interface component includes circuitry for implementing a current loop with the common HART device to operate in a range of approximately four to twenty milliamperes; and a programmable logic device coupled to a suicide relay switch in each channel interface component for alternatively activating and deactivating the redundant pair of channel interface components by connecting and disconnecting respective current loops to provide a master channel and a slave channel, wherein the programmable logic device is programmable to operate the redundant pair of channel interface components in either a sensing mode or an actuator mode; wherein each channel interface component includes:
a loop voltage supply for powering the current loop, wherein the loop voltage is controlled by a digital signal from the programmable logic device that is passed through a digital-to-analog converter (DAC);a voltage modulator and a current regulator arranged in series with a ground, wherein the voltage modulator provides modulated pulses onto the current loop while operating in the sensing mode, and the current regulator provides a current specified from the programmable logic device onto the current loop while operating in the actuator mode; andan isolation barrier that isolates the channel interface component from both a paired channel interface component and from the programmable logic device.