Current Loop Transmitter Circuit for Dry Contact Input Expansion

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Solution Overview

Problem

Monitoring and automation systems often face limitations in the number of digital inputs available, making it costly and time-consuming to add new digital inputs to accommodate additional dry contact switches, which are needed to monitor various process states.

Innovation Solution

The implementation of current loop transmitter circuitry that repurposes an existing unused analog input as a digital input by translating the state of a dry contact switch into a current loop output current, allowing the system to interpret the switch state through measurable current levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If new digital inputs are added to accommodate additional dry contact switches, then the system can monitor more process states, but the system cost and installation time increase

Engineering Contradiction:

Improveinput monitoring capabilityVSAvoidsystem configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes an existing analog input channel perform multiple functions: it can still receive analog signals when needed, but can also be configured to receive dry contact switch inputs by connecting the switch terminals to the analog input channel. This multi-functionality allows the same hardware to adapt to different monitoring needs without adding new physical inputs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system allows dynamic reconfiguration of input channel functionality. An analog input channel can be dynamically assigned to monitor dry contact switches through software configuration or jumpers, enabling the system to adapt its input capabilities based on operational requirements without physical hardware changes.

Inventive Principle:

Principle #15Dynamics

2Ease of manufacture

If existing analog inputs are repurposed as digital inputs, then hardware upgrades are avoided, but programming and configuration time are required

Engineering Contradiction:

Improvesystem expansionVSAvoidconfiguration time

Core Design Contradiction:

Ease of manufactureVSLoss of time

Solution Approach 1:

The system provides self-service capabilities through automated detection and configuration. When a dry contact switch is connected to an analog input channel, the system can automatically detect the switch type and configure the appropriate monitoring parameters, reducing manual programming time and making the system easier to expand.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables the monitoring of additional dry contact switches with minimal downtime and programming, effectively expanding the system's input capabilities without the need for physical hardware upgrades.

Implementation Method 1

current loop transmitter circuitry that repurposes an existing unused analog input as a digital input by translating the state of a dry contact switch into a current loop output current

Methodology Applied

Scientific EffectOhm's Law: Ohm's Law

Data Source

PatentUS12237128B2Current loop transmitter circuitry for monitoring a dry contact switch state

Publication Date: 2025.02.25 CORNELL PUMP COMPANY LLC

AI summary

A device includes a device input, an output connector configured to connect to a current loop, and current loop transmitter circuitry. The current loop transmitter circuitry receives, via the device input, an input from a dry contact switch, and translates a state of the dry contact switch to a current loop current. The current loop transmitter circuitry transmits the current loop current via the output connector through the current loop.