Honeywell International Inc.

Benjamin J Stad

Paul B Gerhart

Angela Lee Lordi

Sudhir Thalore

Christopher Paul Ladas

Paul Gerhart

A programmable interface circuit includes channel(s) including a digital logic block having terminals for receiving control signals from a process controller block, for providing logic signals, and terminals for receiving processed signal data. An analog logic block includes a current output digital to analog converter (DAC). An output circuit block includes first and second field terminals (S1,S2) and a sense resistor, wherein current from the DAC is coupled to S1 and the sense resistor is coupled to S2. The analog logic block includes a first and a second multi-channel multiplexer (MUX), an operational amplifier, and an analog to digital converter (ADC). The control signals automatically select from signal modes including an analog output (AO) mode, a digital output (DO) mode, an analog input (AI) mode, a digital input (DI) mode, and at least one additional signal mode provided by adding a sub-mode to the AI mode or DI mode.

Method and apparatus for automatically selecting a plurality of modes for programmable interface circuit by coupling field devices to process controllers

An open-wire detection system and method includes a current transmitter that can be connected to one or more wires, wherein the current transmitter provides a minimum current and/or a current that is greater than the minimum current. An anti-aliasing filter is connected to an analog-to-digital converter, such that the anti-aliasing filter receives the minimum current provided by the current transmitter and provides an output signal to the analog-to-digital converter. A noise filter is generally connected to an open-wire threshold detector, wherein the noise filter and the open-wire threshold detector permit detection of input levels below the minimum current provided by the current transmitter. An output from the open-wire threshold detector can be sampled multiple times at intervals that correlate with a frequency of a plurality of digital signals to produce sampled data, such that if the sampled data is below the minimum current, one or more of the wires (e.g., a return field wire and/or a field wire connected to a power supply) is reported as constituting an open-wire.

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Cinnaminson, NJ, United States of America

Benjamin J Stad