Communication system for process field device

摘要

A field device for use in an industrial process, includes a process interface element configured to measure or control a process variable. Communication circuitry is configured to communicate with another location. A communication system is configured to provide communications between at least two components in the field device. A signal inverter couples an inverted signal from the communication system to other circuitry to thereby reduce interference received by the other circuitry.

主权项

1. A field device for use in controlling or monitoring a process variable of an industrial process, comprising:
a process interface element configured to measure or control the process variable of the industrial process; a first communication system including a single ended transmitter and receiver; a second communication system configured to provide communications between at least two second components, the second communication system comprising a signal source that produces a signal that couples to the first communication system through electromagnetic intersystem coupling to form an interference signal in the first communication system; a signal inverter coupled to the output of the signal source and configured to receive and invert the signal produced by the signal source to produce an inverted signal that is the inverse of the signal produced by the signal source and couples to the first communication system through electromagnetic intersystem coupling to produce an injected signal in the first communication system to thereby reduce interference from the second communication system to the first communication system, wherein the injected signal has a phase, amplitude and wave shape which are an inversion of the interference signal; and wherein the field device is configured to communicate with another location in the industrial process; wherein the first and second communication systems communicate digital information and the first communication system comprises loop input/output circuitry used to communicate with a remote location over a process control loop and the second communication system comprises local databus communication circuitry used to communicate locally.