A standard for equipment interfaces should maintain diversity and differentiation between vendors' systems and make the integration and maintenance of these systems straightforward and efficient. Such a standard should also address communication protocols, data transfer, and recipe management. The goal would be to provide a flexible, regular interface that significantly reduces the time and effort required to add plug-and-play and other vendor equipment interfaces to the plant's process control system.
The problemAlmost all pharmaceutical, biotech, and biopharmaceutical plants use packaged equipment provided by third party vendors and equipment suppliers. Typically, these skids and packaged equipment are delivered complete, with vendor-supplied process control systems and operator interfaces. Overall, this approach is efficient and cost-effective because the vendor can supply the control-system elements and programming to deliver the required functionality and provide the user with corresponding warranties and performance guarantees.
Regardless of the supplier chosen or the type of system delivered, plant-operations personnel typically desire to include this type of equipment in their main process control systems to monitor and collect data. This inclusion requires an interface to be installed between the plant's process control system (typically a programmable-logic-controller-[PLC] or distributed-control system) and the vendor-supplied equipment (typically a small PLC or microprocessor-based system). Because dozens of possible hardware and software solutions exist, a vendor's process control solution rarely matches that of the strategy employed by the manufacturing site.
Another requirement in many bio/pharmaceutical plants is multipurpose manufacturing using plug-and-play equipment on skids. For example, a portable tank utility panel may perform production preparation, manufacturing operations, and cleaning-in-place (CIP). The utility panel, in this case, is designed to work with portable tanks of different styles, sizes, and functionalities. Some portable tanks may be agitated. Others may have level, pressure, and temperature instrumentation. The plant personnel may desire to roll the plug-and-play equipment up to the utility panel and connect the two for a particular function such as CIP. The process control system will be required to interface with the equipment to perform and monitor each task.
One common scenario is a purification suite where one or more chromatography skid types may be moved into position for a particular product campaign. In this plug-and-play scenario, the process piping, functionality, and operating conditions may be quite different from skid to skid. The process control system needs to not only recognize the type of skid moved into that position but also how to control and monitor the skid.
The solution for connecting the vendor-supplied equipment to the plant's control system nearly always requires custom hardware and software interfaces. These interfaces may or may be difficult to define, develop, install, test, or modify.
For example, if a vendor supplies a controller with a proprietary communications protocol, it may be difficult or impossible to connect that equipment to the plant control system without a special converter box or communications driver. Once installed, this interface may not function correctly if the plant's control system is upgraded in the future.
The interface problem is compounded in the case of plug-and-play equipment packages because a single location now must work with multiple interfaces. As manufacturing space becomes more expensive and the use of disposables and portable equipment grows, standardizing the interface of vendor packages and plug-and-play systems to the plant's control system becomes a critical issue.
Industry and manufacturing standards and guidelines such as ISA S88, ISA S95, and GAMP5 have helped to streamline the definition, documentation, programming, and testing of process control systems in the bio/pharmaceutical industry. Using these standards allows companies to reduce automation costs from project definition through validation. The last bastion of "customization" in process control continues to be in the interfaces between the process control system and vendor-supplied equipment packages.
The author proposes a single industry standard that addresses:
The author would be pleased to discuss the effort to establish a standards-based approach to plug-and-play pharmaceutical equipment with all interested parties.
Scott W. Sommer is an automation technology manager at Jacobs Engineering Group,
Street, Suite 3000,