Software FSK Modem Microcontroller for Isolated PLC Channels
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Solution Overview
Problem
Existing FSK modems in PLC systems require additional hardware, such as UARTs and isolation barriers, increasing cost and space, and suffer from poor signal quality and inability to implement design improvements like filters and adaptive algorithms, especially in multi-channel configurations.
Innovation Solution
A micro-controller with a built-in software-implemented FSK modem function eliminates the need for separate hardware modems and UARTs, providing improved signal fidelity and channel density by integrating FSK modem operations, including zero crossing detection and adaptive center point algorithms, within the micro-controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate hardware modems and UARTs are used in PLC systems, then FSK modem functions can be implemented, but hardware complexity and cost increase
Solution Approach 1:
The patent combines the FSK modem function and UART functionality into a single integrated circuit device. The modem includes both the FSK modulator/demodulator and the UART in one unit, eliminating the need for separate hardware components. This merging reduces the number of discrete parts, simplifies the overall system architecture, and lowers hardware complexity while maintaining full FSK modem capability.
2Adaptability or versatility
If separate hardware modems are used in PLC systems, then FSK communication is enabled, but device cost increases
Solution Approach 1:
By integrating multiple functions (FSK modem and UART) into a single device, the patent reduces the total component count and bill of materials. This consolidation lowers manufacturing costs through fewer parts to source, assemble, and test, while still providing complete FSK communication capability for industrial PLC systems.
3Quantity of substance
If FSK modems are shared in multi-channel designs, then channel density increases, but signal quality deteriorates
Solution Approach 1:
The patent implements dedicated FSK modem instances for each communication channel within the integrated device. Rather than sharing a single modem across multiple channels, each channel has its own modem instance, ensuring that signal processing resources are not contended. This segmentation maintains high signal quality and reliability for each channel while achieving high channel density through the integrated architecture.
4Adaptability or versatility
If separate hardware modems are used, then FSK modem functions are available, but space requirements increase
Solution Approach 1:
The integrated circuit device combines FSK modem functionality, UART operations, and support for multiple communication channels into a single compact component. This merging dramatically reduces the PCB space required compared to discrete hardware modems and UARTs, allowing high channel density while maintaining full modem functionality for industrial communication applications.
Data Source
AI summary
A micro-controller to perform the FSK (HART) modem functions as well as communications and control functions in an isolated channel implementation is described. In one embodiment, the micro-controller comprises: a processor, an analog-to-digital converter configured to transform received analog signals into digital values at a predetermined digital sample rate; and a memory unit containing a set of computer-executable instructions that, when executed on the processor, provide a built-in FSK bi-directional modem function that converts the received digital values into binary signals. The FSK (HART) demodulation function is performed by the micro-controller with the built-in FSK modem function in three sequential phases implemented in computer code: (1) zero crossing and amplitude detection; (2) bit stream and timing generation, and (3) character generation and bit synchronization.