Programmable Interface Circuit for Field Devices
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Solution Overview
Problem
Conventional interface circuits for industrial settings are limited in their ability to handle multiple I/O functions, require pre-planning for wiring connections, and fail to support various voltage and differential input types, leading to inefficiencies and potential errors in device control.
Innovation Solution
The development of programmable interface circuits that can be configured by users to support analog or digital, current or voltage, differential or grounded modes without pre-planning, utilizing a digital logic block, analog common resource block, and output circuit block with multiplexers and converters to enable connection to a wide range of field devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional interface circuits use general-purpose I/O pin designations, then the circuit can support basic I/O functions, but it cannot adapt to different field device types without wiring changes
Solution Approach 1:
The interface circuit employs dynamic configuration capability where I/O channels can be programmatically assigned to different functions (analog input, analog output, digital input, digital output) after installation. This allows the system to adapt to different field device types without physical wiring changes, resolving the contradiction between adaptability and wiring complexity
Solution Approach 2:
The system changes the operational parameters of I/O channels through software configuration rather than physical reconfiguration. Each channel's function, voltage range, and input type can be modified by changing configuration parameters, enabling adaptation to various field devices without altering the physical wiring infrastructure
2Adaptability or versatility
If interface circuits require pre-planning for wiring connections, then the wiring can be optimized for specific functions, but it cannot accommodate post-installation changes in I/O point types
Solution Approach 1:
The interface circuit allows dynamic reconfiguration of I/O channel functions after installation through software programming. Users can change I/O point types, assignments, and roles without time-consuming wiring modifications, eliminating the need for pre-planning while maintaining full functionality
Solution Approach 2:
The system replaces the mechanical wiring configuration process with software-based configuration. Instead of physically changing connections to adapt to different device types, users programmatically reassign channel functions, dramatically reducing the time required for adaptations
3Adaptability or versatility
If interface circuits use fixed I/O function assignments, then the circuit design is simpler, but it requires three or more wire connection sites for broad functionality
Solution Approach 1:
The interface circuit implements universal I/O channels that can perform multiple functions (analog input, analog output, digital input, digital output) through software configuration. This multi-functionality eliminates the need for separate dedicated circuits for each I/O type, reducing the number of wire connection sites required while supporting a broad range of functions
Solution Approach 2:
The system merges multiple specialized I/O functions into unified programmable channels. By combining analog and digital capabilities, input and output functions, and various voltage ranges into single configurable channels, the circuit reduces the number of physical connection points needed while maintaining comprehensive functionality
4Adaptability or versatility
If interface circuits require user decisions at wiring time about field device nature, then the wiring can be optimized for the specific device, but it cannot support voltage or differential input types
Solution Approach 1:
The interface circuit dynamically adapts to different input types (voltage, differential, current) through software configuration rather than requiring pre-determination at wiring time. The system can be reprogrammed to support various input types as needed, eliminating the need for users to make irreversible wiring decisions about device characteristics
Solution Approach 2:
The interface circuit implements universal input capabilities that can handle voltage inputs, differential inputs, and current inputs through the same physical connection points. This multi-functionality is achieved through programmable configuration that adapts the circuit's behavior based on the connected device type, simplifying wiring while maintaining versatility
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
These programmable interface circuits enable a single interface to control multiple I/O functions, reduce wiring complexity, and detect defects such as short circuits, ensuring high availability and flexibility in industrial applications.
Implementation Method 1
An analog logic block includes a current output digital to analog converter (DAC)
Implementation Method 2
The analog logic block includes a first and a second multi-channel multiplexer (MUX), an operational amplifier
Implementation Method 3
The analog logic block includes a first and a second multi-channel multiplexer (MUX), an operational amplifier, and an analog to digital converter (ADC)
Implementation Method 4
The analog logic block includes a first and a second multi-channel multiplexer (MUX)
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A programmable interface circuit (100) includes channel(s) including a digital logic block (110) having terminals (116e) for receiving control signals from a process controller block (170), terminals (111, 112) for providing logic signals (111a, 112a), and terminals for receiving processed signal data. An analog logic block (120) includes a current output digital to analog converter (DAC) (121). An output circuit block (140) includes first and second field terminals (S1,S2) and a sense resistor (146), 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) (131, 132), an operational amplifier (135), and an analog to digital converter (ADC) (122). 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.