PLCs | What happens when they stop making your model?

Modern electronic components do not stay in production long as evidenced by devices such as computers and mobile phones. How then do plant owners manage with their sophisticated process control and automation systems? Jeremy Shinton of Mitsubishi Electric asks what happens when the age of a PLC becomes an issue?

Firstly, automation products have a longer design life than consumer products, and the manufacturers plan for production lives of five to ten years. Nevertheless, the integrated circuits (ICs) they use are manufactured by the mainstream producers until production becomes uneconomic. In addition, newer ICs offers advantages in speed, cost and performance features, so keeping modern makes sense.

Most industrial machinery is controlled by a PLC or similar controller. These devices are so reliable they are often forgotten by the plant engineers until they fail. It is not unreasonable for controllers to eventually develop a fault – for example in a PSU (power supply unit) or CPU (central processor unit) or a mechanical issue with a relay output card. What happens if one does stop?

– What is the down-time cost during the repair?

– Once fixed do you just forget about it until the next time?

– Would you be better off replacing the whole controller with a new one and if so should you go for a like-for-like swap out or upgrade to a state of the art control unit?

– If you upgrade, does this affect other parts of the control system and thus lead to more work and expense?

Coping with change

As both a manufacturer and user of PLCs, Mitsubishi Electric prides itself on maintaining continuity with each new generation of controller and associated software. For example, Mitsubishi Electric A and Q-series controllers manufactured in the 1980s can be directly swapped out for the latest models. Similarly, the PLC code from a thirty-year-old device can be transferred to the latest hardware. Software support tools and utilities are available free of charge and full reports for any function changes are identified.

Communication and productivity

With Mitsubishi Electric’s backward compatibility, the cost of change is minimal. Many customers use this system to progressively upgrade their plant-wide control systems and processes one step at a time, with minimum fuss and the confidence that they will be supported for years to come.

Probably the most significant benefit of transition is the opportunity to add new fieldbus communications, Industrial Ethernet and Internet connections to existing systems. Upgraded systems with improved communications allow users to take advantage of getting much more information from the plant and ensuring it is running at its optimal performance.

Benefits of change

Newer generations of Mitsubishi Electric PLCs offer data-logging capabilities, for compliance regulation and connectivity to databases for recipe and historian transactions, making manufacturing processes more transparent. Diagnostic options built into today’s controllers mean reduction of downtime while their increased programming capacity enables machinery enhancements which could lead to an increase in productivity.

Go here for Jeremy’s full article

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