Improved communications across LCD plantProduction of flat LCD screens at one of the largest plants in Asia has steadily ramped up to meet the ever-increasing demand. The process is now highly automated, so data communications are critically important. The choice of a high-speed Ethernet based open network, CC-Link IE, to run the automation comms at the plant could point towards the future for many more automation installations in Asia and Europe.
Flat-panel TVs and monitors have been one of the strongest growing consumer products of recent years. Production demand has grown, as has the number of product variations. And of course consumer price pressures require constantly improving efficiency. All this can only be achieved by more effective communication and data sharing between the manufacturing cells that make up the plant.
Automation engineers recognise that consumer electronic plants typically evolve in a fairly ad-hoc manner as demand increases, so the control system architecture often has to marry together diverse subsystems producing sub-optimal overall performance. At the Asian LCD plant, the situation ended up with the high level MES and ERP systems using standard TCP/IP Ethernet, while the shop-floor systems implemented Mitsubishi Electric's MELSECNET/H at the control level, and the open standard CC-Link.
While having served the facility well in the past, it was perceived that the data communications capacity and speed of MELSECNET/H was lagging behind the current requirements. Further, it was felt that a standard optical fibre cable would make maintenance and reconfiguration easier while providing better connectivity to PC systems.
CC-Link IE (Industrial Ethernet) was seen as an improvement on this with improved data capacity and speed (1Gbps), the use of a generic optical cable and better PC connectivity. Importantly, its diagnostics capability also made maintenance easier. Critical for industrial applications, it is also fully deterministic. Further, its highly fault tolerant features improve efficiency and productivity.
In order to overcome the limitations of the existing control system it was decided to upgrade to a CC-Link IE network across the whole LCD plant. This offered many advantages, such as a 40 times theoretical increase in communication speed, together with an eight-fold increase in data capacity.
The control network in the LCD plant is now rationalised to a simple format. The major systems such as ERP and MES use the industry standard HSMS Protocol. Shop floor systems that control equipment and provide facilities and production site information are established using CC-Link IE. Data sharing between equipment or facility hardware controls is also based on CC-Link IE or CC-Link fieldbus.
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