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Welsh Water uses IEC1131-3 software to reduce system development and maintenance costs.

Welsh Water has hundreds of PLC's installed across its water and waste processing sites. In common with other water companies, regional policies have resulted in the use of a wide variety of manufacturers' products. Many of these systems have been implemented by different systems houses, who have different programming methodologies and documentation standards.

This has resulted in control systems with similar functions ending up with completely different software styles and standards, all of which have to be supported. Maintenance personnel have to be familiar with a large variety of PLC types and models, which in itself represents a large training effort. Furthermore, much time can be spent comprehending a variety of support documentation. Welsh Water's ongoing programme of capital schemes adds daily to this task.

The solution is their Modular Software Initiative that embraces the IEC1131 standard and Object Orientated design methods.
IEC1131 has been chosen for the benefits it confers in producing well documented, structured, compact and reusable code. Whilst adopting IEC1131 will result in portable application software in the future, HCL see real opportunities in reducing the cost of their installed systems, today.

Welsh Water has signed a framework agreement with Mitsubishi Electric to supply PLC products and MX32 Scada software. Mitsubishi was the only supplier supporting IEC1131-3, which was a significant element in their offer.

HCL's plan is to use Mitsubishi's Melsec Medoc Plus (MM+) software to create a library of modules. In the first instance modular software will be aimed at capital projects. As existing systems are replaced, they will be upgraded to conform with the new standards.

This will produce a common 'look and feel' across all sites in all regions, giving improved efficiency both for operations and support staff. For the new sites, they estimate that 70-80% of the system can be implemented using standard modules, with consequent cost savings. These modules will also be used by their systems suppliers, who will also use be required to adopt the same uniform testing and implementation methodology, which will further reduce long term costs.