Web Enabled I/O Modules for Industrial Control Systems
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Solution Overview
Problem
Industrial control systems face challenges in providing cost-effective and efficient remote monitoring and Web access to I/O modules, as existing solutions require expensive Web server modules and increase processing burdens on programmable logic controllers, and may lead to conflicts between Web-based interfaces and the programmable logic controller.
Innovation Solution
I/O modules with integral Web servers that communicate directly with the Web, eliminating the need for a programmable logic controller intervention, and include a processing unit to manage data transfer between the Internet and I/O interfaces, with a write disable command to prevent conflicts and allow selective blocking of Web access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Web server module is added to provide remote Web access to the industrial control system, then Web access capability is improved, but system cost and device complexity increase
Solution Approach 1:
The patent combines the Web server functionality directly into the I/O modules, merging multiple functions (I/O processing and Web serving) into a single integrated component. This eliminates the need for separate Web server hardware and reduces overall system complexity while maintaining full Web access capability.
Solution Approach 2:
The I/O modules are designed to perform multiple functions: traditional I/O processing and Web server operations. By making the I/O modules universal components that can handle both control I/O and Web communication, the system achieves Web access capability without adding dedicated Web server hardware.
2Adaptability or versatility
If a Web server module is added to provide remote Web access, then Web access capability is improved, but processing burden on the programmable logic controller increases
Solution Approach 1:
The patent segments the Web server functionality from the main PLC and places it directly in the I/O modules. This distribution of functionality allows the PLC to focus on control processing while I/O modules independently handle Web communication, reducing the PLC's processing burden.
Solution Approach 2:
The I/O modules act as intermediaries between the industrial control system and the Web network. They directly communicate with web browsers and handle Web protocol processing, serving as a mediator that shields the PLC from Web communication overhead and processing demands.
3Speed
If direct Web communication with I/O modules is enabled, then Web access speed is improved, but potential conflicts between Web-based interfaces and the programmable logic controller arise
Solution Approach 1:
The patent implements preliminary coordination by having the PLC send write disable commands to I/O modules before executing control operations. This advance coordination ensures that Web-based modifications are prevented during critical control periods, maintaining control reliability while allowing fast direct Web access when appropriate.
Solution Approach 2:
The system uses feedback mechanisms where the PLC monitors its operational state and sends appropriate commands (write disable or write enable) to I/O modules based on current control needs. This feedback loop ensures that direct Web communication does not conflict with active control operations, maintaining system reliability.
Data Source
AI summary
An industrial control system provides a programmable logic controller communicating with I/O modules which provide an electrical interface to controlled equipment and which support web servers for communication of I/O data directly with the Internet. The programmable logic controller communicates with the I/O modules over a control-network which may be separate from or shared with the Internet communications. A lock-out system prevents collisions between web clients writing to I/O and allows the programmable logic controller to limit web access to critical I/O points.