Batch to benefit big time

Batch process industry manufacturers like Cadbury Schweppes, Pfizer and Hygrade Foods are turning to existing and new operational and IT standards initiatives to provide the foundation on which to build new levels of business performance. Why? “The trends are towards manufacturers having to make more product variations in smaller batch sizes, and bring them to market more quickly,” says Chris Haines, business development manager at factory automation giant Rockwell Automation. “So they need to be more flexible and react more quickly to changing customer demands.” Additionally, batch manufacturers suffer from an inescapable liability, explains John Croft, consultant engineer at industry colossus ABB. “With continuous processes, the hardware and software costs predominate, but in a batch-type implementation the cost of the application is the biggest element.” And that high application cost, says Robert Babecki, product manager at UK-owned controls firm Invensys, has one main cause: “Phase logic typically accounts for well over 75% of the project engineering effort, and complications here can have a tremendous impact on its overall scope.” One standard in particular – S88, or Batch Control Standard ANSI/ISA-88.01-1995 – provides a modular approach to batch processes that is aimed at overcoming the deficiencies of the old-fashioned monolithic approach to PLC (programmable controller) and DCS (distributed control system) programming. And although suited to both automated and manual processes, S88 usually goes hand in hand with automation projects. S88 is an unusual standard in a number of ways. It doesn’t have any competitors and, according to Croft, “it seems to be becoming universally accepted and understood by both the marketplace and the vendors.” Most importantly, in the words of Nigel Moorby, control systems analyst at global beverages and confectionery company Cadbury Schweppes, “It is a very usable standard, a very practical type of standard.” However, as Carey Clements, product manager with advanced controls software specialist Honeywell POMS, points out, “It is not a technology-specific standard – it is technology independent.” Of course, on the one hand this is an advantage – in that all 10 of the leading vendors of batch control software have products that are more or less S88-aware, and as Croft explains, the benefit is this “effectively means that all S88-recipes are equipment-independent”. On the other hand, there is a downside to this lack of a technology restriction: there’s no such thing as an S88-compatible system. Although S88 can help separate the recipe procedures, which reside on a PC, from the programming code running in the PLC or DCS, you can’t take one S88-aware product and plug it into another. “The industry is in protectionism mode – this physically stops people going out and buying best of breed,” observes Moorby. Nevertheless, S88 provides many substantial benefits. First and foremost is modularisation, and the reuse that flows from it. Each automation application is broken down into modules which can be easily understood, and hence easily tested once built. More significantly, the same modules can be used by more than one application. This reuse slashes the time taken to launch a new process, cuts the cost of developing the application – and also improves the predictability and consistency. “We get reusable components that are implemented to a standard that is widely recognised, easy to implement and gives us a higher degree of confidence,” explains Willie Power, process control team leader with Pfizer, the research-based global pharmaceutical company. And by strictly defining the terms used to describe processes, another excellent spin-off is improved communication. “A systems engineer may have a different idea of what a step is to a process engineer,” explains Moorby. “S88 stops these misunderstandings – that is one of the fundamentally important benefits.” This improved communication isn’t just relevant within the enterprise, says Haines: “It helps with connecting manufacturers to contractors – if they want to go out to contract, then if they are talking the same S88 language, the end result is that it helps them get that product to market more quickly.” Standards-based modularisation achieves other benefits – it separates the knowledge and data associated with the product or procedure from that which relates to the plant and equipment itself. “If a system is properly designed, the benefit that S88 will give is that the knowledge associated with making the product, the intellectual property, is separate from the knowledge of how a piece of equipment has to be operated,” explains Babecki. Better plant utilisation Thus production people can build a recipe at the top level, without any need to know or understand the software or technology on the plant where the products will be made. At the lowest level, the operations consist of a series of structured phases – software elements that interact with the database, and the province of software engineers rather than production experts. This means you can get different control systems to work together, says Moorby. “Integration is much easier if you use S88. The transfer of information from one control system to another becomes much easier, although it still needs engineering.” S88.02 is intended to make integration even easier in the future, by defining data exchange tables in ANSI standard SQL. The data table structures provide the definitions that allow vendors to make their tools interoperate – leaving it up to manufacturers to require conformance to the S88.02 Section 5 tables if they want the systems they buy to exchange information. And once S88 is coupled with integration as well as automation, the benefits really start to accrue. S88-aware systems can help achieve better batch-to-batch consistency, plant utilisation and throughput, as well as much easier plant operation. “From a user interface point of view it tends to make plant operation easier and more consistent – you get a view of how the plant is operating in terms applicable to that manufacturer,” explains Haines. “The operator doesn’t have to understand the PLC or how it’s working: he sees things in terms of what you do in your plant – so you identify problems earlier and get tighter control.” However, S88 doesn’t come cheap. “The problem with the batch control engines at the moment is that they are not cost-effective,” says Moorby. “The cost of the software for those engines is prohibitive, so it stops people going down that road. But, you can quite happily write SCADA and PLC code in line with S88 without going out to buy an engine.” Another barrier is the usual one of resistance to change. “If a manufacturer has been making things safely and profitably without S88, there is a reluctance to change and adopt something new,” says Babecki. “By the time they get phase logic working correctly they don’t want to touch it – the real challenge that the customer is faced with is getting that huge investment in phase logic moved to a modern implementation.” There’s another point though: when implementing S88, it’s also possible to get it wrong. “You need the right balance between the richness of the phase set and the capabilities of the individual phases,” explains Croft. “If your phases are too simple your recipe is very complex and less understandable; if your phases are too complex then you have no flexibility. In some circumstances you need quite comprehensive phases, but you also need some that are very simple that you can include to make minor changes to a recipe.” S88 isn’t the only standard that comes to play in process industries. At Pfizer, for example, project specifications are modelled on GAMP (good automated manufacturing practice), an automation standard for the pharmaceutical and biotechnology industries. And S88 also provides the foundation for S95 (enterprise/control system integration), a standard that addresses the interface between business and control systems – linking process control with ERP (enterprise) systems via an MES (manufacturing execution system) layer. “It’s the complete opposite of S88,” explains Moorby. “It provides a common framework, a common discussion point, but not a product you can go out and buy. In fact, while it’s a very useful document to allow people to think about what they’re trying to do, it creates in people’s minds the idea of this middle level called MES, which in reality often isn’t there – the functionality tends to exist in either the upper or lower levels.” At Cadbury Schweppes, the conceptual functions of MES have been migrated either up into the ERP layer, using SAP, or down into the process control layer – planned maintenance, for example, has moved up into the ERP physical level. Meanwhile, when it comes to the technology to integrate systems, there’s a great deal of interest in the use of XML. “The interface from the unit controller to the batch controller, or even up to ERP systems, can be implemented with a web-server type, XML-type interface,” says Honeywell’s Carey. XML in the recipe And industry is beginning to agree. The IT director of a large privately-owned UK food manufacturer which didn’t want to be named told MCS: “XML is now being seriously looked at by manufacturers with an eye to improving the complete business process by using best-of-breed systems in an integrated manner.” His company is already working on integration projects using XML. “Primarily, we are looking to take information from – and to – the weigh scales using XML, so the weigh scales become a part of the transaction system.” Weigh scales are integral to the production process, weighing ingredients for cooking, and weighing product into its ready meals. In fact, it’s working with both BASDA eBIS-XML and Simple-eb XML. “We are looking at centralising the maintenance of as many as possible DCS recipes and specifications and their associated item maintenance using the Geac System 21 ERP system, which I believe will reduce cost and improve efficiency, ensuring the production recipe is always correct,” says our contact. “Part of the specification for future equipment will be that its software must use these XML standards for interface control.” As to whether S88 should be a priority, Haines believes: “The adoption of S88 terminology is accepted throughout the manufacturing base, whereas the take-up of S88 products will depend on the complexity of the process.” Carey has a formula to guide manufacturers through that complexity. “Multiply the number of products by the number of production lines, and then multiply by the number of changes you have to make to those products. The higher the number, the more justification you have.” In summary, Croft doesn’t feel S88-aware products are receiving enough attention. “It should be higher up the business agenda. When I consider the industry pressures that there are today, it’s a very competitive world. They need to improve quality and turnaround time; a lot of our clients are getting smaller orders, and of course there’s increasing customisation, and you’ve always got the cost pressure. Modern systems that are S88-compliant can help.”