Web HMI Material Tracking Between PLC Signal Updates
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Solution Overview
Problem
Existing SCADA HMI systems struggle to accurately track the head-end and tail-end positions of materials being rolled in hot rolling lines without waiting for the reception cycle of PLC signals, leading to delayed and inaccurate tracking displays.
Innovation Solution
A SCADA web HMI system that processes PLC signals at each reception cycle, using a processor to calculate and display the head-end and tail-end positions of materials on the HMI screen, even before the next PLC signal is received, by integrating conveyance speed and elapsed time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system waits for PLC signal reception cycle to update material position, then data accuracy is maintained, but tracking responsiveness and display update frequency deteriorate
Solution Approach 1:
The system performs preliminary actions by calculating estimated material positions using conveyance speed and elapsed time before actual PLC signal data is received. This allows the HMI screen to display proactive tracking information in advance, improving responsiveness without sacrificing accuracy when real data arrives for correction.
Solution Approach 2:
The system implements feedback by using received PLC signals to correct and verify the estimated material positions. When actual position data is received, it feeds back to adjust and refine the tracking display, ensuring accuracy while maintaining continuous update cycles between signal receptions.
2Speed
If the HMI screen is drawn at a shorter drawing cycle, then tracking display responsiveness improves, but system processing load increases
Solution Approach 1:
The system applies partial action by performing selective calculations only for material positions that need updating, rather than completely recalculating all system parameters at each drawing cycle. This reduces processing load while maintaining the responsiveness of the display updates.
3Measurement precision
If the system estimates material position without waiting for PLC signal, then tracking accuracy improves, but risk of display error increases
Solution Approach 1:
The system prepares cushioning measures by implementing correction mechanisms that activate when PLC signals are received. This beforehand preparation ensures that any potential estimation errors are corrected using actual measured data, maintaining reliability while enabling accurate tracking between signal receptions.
Data Source
AI summary
A SCADA web HMI system draws an HMI screen including a first material-to-be-rolled part arranged in a first zone and an extendable/contractible second material-to-be-rolled part arranged in a second zone. The first and second material-to-be-rolled parts are drawn at each drawing cycle shorter than a reception cycle of PLC signals. At each drawing cycle after a first PLC signal is received, a first material-to-be-rolled part head-end position is calculated based on a conveyance speed included in the first PLC signal and an elapsed time. A drawing size of the first material-to-be-rolled part is set to a length from an entry side of the first zone to the first material-to-be-rolled part head-end position. When a second PLC signal is received, the first material-to-be-rolled part head-end position has not reached the second zone, the drawing size of the first material-to-be-rolled part is set to a zone length of the first zone.