How To Remove The Burden Of A Legacy PLC System

However good your legacy PLC system, there comes a time when it is no longer fit for purpose. Improvements become more difficult to make, reliability declines and spares are either expensive or no longer available.

Moreover, integration with new equipment becomes complicated due to slow or outdated network communications. Even when a mechanical system is functioning properly, there comes a time for replacing the legacy PLC system – before the system makes the decision for you. This was the situation facing Master Maltster Crisp Malt in Norfolk.

To ensure optimal quality and productivity, the control systems check the processes for converting the grain into malt. Malting is a very delicate process, due to the quality and variability of the raw materials. This means that small improvements in process control can deliver big improvements in quality. Furthermore, the grain kernels must remain alive in order to germinate.

Legacy PLC system

As David Spiers, Group Engineering Manager at Crisp explains. “The existing GEM 80 PLCs were becoming unreliable which left us exposed to the risk of long-lasting unplanned downtime events. For example, if we had a power outage it would take 3-4 hours to return the system to full operation.

Keeping the malting process balanced requires a responsive control system and the ability to make timely upgrades is essential. Increasing the detection and response speed for process anomalies has a significant impact on the process. With batch sizes measured in tons, Crisp decided to replace six legacy PLCs with new high-performance Mitsubishi Electric Q PLCs.

Paul Judge, Key Account Manager at Mitsubishi Electric adds. “Due to the limited room available in the existing panels, conducting a phased system migration was not an option.” Thus, Mitsubishi Electric, integrator Suffolk Automation and Crisp had to complete the entire re-fit operation in one go. They minimised downtime by replacing the control systems in a scheduled service window of four days.

Connection to the PLCS is via CC-Link IE open Ethernet network with 1 Gigabit bandwidth, using fibre-optic cables. This gives Crisp real-time communications between manufacturing areas and up to enterprise systems. Management also benefits from better plant performance and more accurate reporting.

Improved control of the processes

The new automation solution also provided Crisp with the level of detail needed to have a greater understanding of real-time variations in the process. They can now track and access parameters like temperature and throughput in real-time. Anomalies are soon detected and acted upon thanks to visible alarms. The upgrade slashed downtime, and empowered operators at Crisp to own their manufacturing processes, leading to improved product quality and consistency.

Looking forward, the maltsters now have a control system that is user-friendly and easy to adjust. They are free to modify and fine-tune the functionalities and process parameters that govern different aspects of the malt as required. In this way, the malthouse has access to state-of-the-art tools that can improve and refine the quality of its products.

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