Web-Based SCADA HMI Architecture for Lower Signal Traffic
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Solution Overview
Problem
Existing SCADA systems face high processing loads and communication traffic issues when handling a large number of signals and client devices, leading to potential communication errors and downtime during system operation.
Innovation Solution
A browser-based SCADA HMI system with client-side installation of the SCADA web program and communication module, utilizing WebSocket connections and inter-domain communication to reduce traffic and load on the server, and efficient data transmission methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the SCADA server device transmits signal data to all HMI client devices using Point to Point connection, then real-time supervisory function is achieved, but communication traffic increases and processing load increases
Solution Approach 1:
The patent segments the HMI client devices into multiple groups, with each WebSocket connection serving a group of client devices rather than individual devices. This segmentation reduces the total number of connections and message transmissions required, thereby decreasing communication traffic while maintaining real-time supervisory capabilities across all devices in each group.
2Productivity
If the SCADA server device processes a large number of signals in real time, then system supervision performance is improved, but high-performance processor and large-capacity memory are required
Solution Approach 1:
The patent implements partial action by having the SCADA server device process and transmit only the necessary signal data to grouped HMI client devices through optimized WebSocket connections, rather than processing and transmitting all possible data to all devices individually. This reduces the processing load on the server while maintaining adequate supervisory functionality.
3Reliability
If the web browser loads the SCADA web program during system operation, then system availability is maintained, but communication traffic may exceed communication capability
Solution Approach 1:
The patent implements preliminary action by pre-loading the SCADA web program into the web browser before system operation begins. This allows the browser to have the necessary program already available in memory, eliminating the need to download additional data during critical system operation periods. Consequently, communication traffic remains within capability limits while system availability is maintained.
Data Source
AI summary
Each of PLCs transmits block data relating to a field device group constituting an industrial plant, to a SCADA server device at a fixed period. The SCADA server device includes a communication driver configured to receive the block data, and a client management circuitry connected to a plurality of HMI client devices in one-to-one relationship and configured to perform WebSocket communication with each of the HMI client devices. Each of the HMI client devices executes a web browser displaying an HMI screen on which parts indicating states of the industrial plant are arranged, and updates states of the parts based on signal data received from the client management circuitry. Each of the HMI client devices includes a client installer for installing a SCADA web program loaded at startup of the web browser.