Control vendors offer lower cost links from plantfloor to office

A key factor in ensuring safe and hygienic food manufacture is information throughout the process, writes Colin Bravington of Omron Electronics. Not only do data need to be gathered at the point of production, but reporting and verification structures for quality assurance and HACCP (hazard analysis critical control points) implementation also mean that a seamless link is required from the plantfloor to the office environment. where the raw data can be converted into meaningful information.

SCADA systems provide a good enabling tool to meet the visualisation and data handling requirements. But new technologies are emerging that provide ideal alternatives for the food processing industry, both in terms of visualisation - and the data entry and monitoring which that implies - and in terms of data manipulation between plant and office.

With these new tools, the user is given effective choices. SCADA still has its place in many process applications, but there are now other options, in the form of man-machine interfaces (MMIs) on the plant floor, and in simple Microsoft-based connectivity tools.

A SCADA system has extensive functionality developed over many years to meet user demand - particularly in manufacturing sites wanting to centralise their supervisory control, process visualisation and data gathering. But food processing is different. The centralisation of supervision and MMIs typical of modern SCADA implementations is generally undesirable. Operations in the food industry are much more labour intensive and immediate plant information is needed on the processing lines themselves.

In addition, data entry on-line is increasingly important, as many process conditions that impact on hygiene, safety and quality can only be measured and entered manually.

With the advent of affordable graphics-based MMIs, the plant floor is no longer reliant solely on SCADA for visualisation and data acquisition. Linking directly to programmable controllers, MMIs give localised information on the plant and direct interaction with it.

Low cost, colour, touch-screen technology from suppliers like Omron provide an ideal interface for process visualisation, including alarm lists, recipe data or process instructions. Touch screens eliminate the need for keyboards in what must be regarded as a hostile environment for such equipment, while direct links to PLCs facilitate process supervision and critical data entry.

So, localised MMIs bring data entry and process monitoring to the plant floor. But a bridge is still needed from there to the office. Traditionally, SCADA systems have had to be used to provide this bridge. Now, though, the ubiquitous use of Microsoft products in the office - with technologies such as ActiveX and COM (Component Object Model) giving seamless data flow and manipulation between office applications - has supplied the catalyst for a new look at linking the business systems to the plant floor.

Omron's version of this concept is FINS Gateway - software that resides on the PCs in the office and provides a seamless link with the PLCs on the plant floor. For users wanting to dig deeper, there are various interface levels all the way down to C++ programming. At this level applications can be developed to access the controller data directly to integrate it with HACCP compliant reporting requirements.