TABLE OF CONTENTS The original developers of the ISA 88 batch control standard made a determined effort to ensure that the models applied to manual operations as well as automated operations. The S88 Design Pattern is not only for automated control systems. It also applies to manual operations and to semiautomated operations (a mixture of manual steps and automated steps). The S88 Design Pattern, however, requires careful application of the recipe/equipment pattern in order to achieve reusability advantages and the ability to quickly develop and change recipes.
The S88 Design Pattern defines a partitioning of the system into two main elements, one defining the equipment's basic capability and the other defining product recipes. The basic equipment capability is the product-independent processing actions the equipment is capable of performing, independent of whether the actions are performed by an operator or by a process controller.
A process cell's basic capability is defined through a set of equipment phases. This applies even if the equipment phases are actions performed by people and the actions are manual operations, such as opening values, starting motors, recording values, or setting set points.
Equipment phases are the interfaces to major processing functions basically, one equipment phase per basic function. Equipment phases should be defined such that any reasonable functionality of a unit can be expressed in terms of the phases. Phases are generally not tailored to the set of known recipes but are product-independent definitions of capability, as shown in Figure 6-1. When following the S88...
