Scalable Scada system matches ever-changing needs

AJ and RG Barber Ltd is using CitectSCADA to provide monitoring, trending and data reporting in the production of its renowned West Country Farmhouse Cheddar cheese. The Citect package is helping to ensure quality in the production of the cheddar, and providing a means for the archiving of data as a back-up to the chart recorders used as part of the British Retail Consortium's requirements for access to production data concerning processed foods.

Jay Hemsley, Engineering Manager at AJ and RG Barber, says: "We mix the best of the old, in terms of natural mixed cheese cultures that produce cheddar with real complexity and depth of flavour, with the best of the new: the most sophisticated automation to underpin our traditional manufacturing methods and ensure the continuous quality of our production. CitectSCADA is an excellent, easy-to-use package that is just right for our purposes. We have used its inherent scalability to develop just what we need over time, and now we benefit from the highest levels of control, monitoring and reporting. It develops as we do; we really cannot fault it."

The Barber family has been farming, and in Somerset, since the early 1800s. Initially the milk produced on their farm was sold, and cheese was just made to feed the family and farm workers. As time passed it proved more beneficial to make cheese than to sell milk, and soon Barbers were buying milk from other nearby farms as well as using all their own milk to make cheese. In the 1950s manufacture concentrated heavily on producing Caerphilly wheels for the Welsh mining community (Caerphilly held its condition underground better than other foods). Today the company has returned to producing West Country Farmhouse Cheddar, which is the focus of the business, and has continued to expand the farm alongside, which now includes the milking of about 2000 dairy cows.

25 PLCs, 500 tags and 90 screens

The CitectSCADA system used at Barber's cheese making facility oversees 25 PLCs that provide primary control at the plant. The SCADA is a 500-tag system with three licences, and 90 screens, 60 of which are operative at any one time. The system is also configured with two servers, providing crucial redundancy to safeguard the complex cheese making process, and the archive of production data.

CitectSCADA was proposed in the early 1990s by JBT Ltd (a Citect Integration Partner) and was chosen as the supervisory interface to the multi-PLC system due to its wide range of standard drivers, leading trend facilities, its free development system and its PLC tag synchronisation feature, which allows tags to be linked directly to PLC programming software. This saves valuable configuration time because a group of tag definitions can be imported in one simple operation. The bi-directional linking feature ensures that changes made in one development environment are updated automatically when projects are worked on simultaneously. Moreover, even when CitectSCADA and PLC projects are worked on separately, the Import and Export feature ensures that both environments are maintained and kept up-to-date.

At present the CitectSCADA package at AJ and RG Barber provides 644 pages of trending data relating to activities such as milk and whey pasteurisation and filtration. All the trends have a two-year life and are totally transparent to operators across all operator screens via comprehensive dynamic mimic displays. In addition, mimics also provide full transparency for monitoring across equipment, including: CIP systems; bulk starter vessels, curd pumps and vats; and activities such as cheese pressing and cycle times. The SCADA also enables Barbers to print out data reports in respect of items such as Silo stock closing levels and Bulk Starter vessel status.

Jay Hemsley states: "In addition to its many operational advantages, a strategic benefit for us as a company is the regular upgrades that are available with CitectSCADA. This means that we have no legacy issues. We are currently looking to upgrade to Version 6, which has the built-in Process Analyst function, a next-generation visualisation tool that will enable our operators to quickly analyse the cause of process disturbances by bringing together trend and alarm data. It will also help our operators to recognise patterns that lead to particular process disturbances, so that in future they can be avoided."