TABLE OF CONTENTS The top-level S88 Design Pattern is the separation of product definition information from production equipment capability. This separation allows the same equipment to be used in different ways to make multiple products, or different equipment to be used to produce the same product. Product definition information is contained in recipes, and the production equipment capability is described using a hierarchical equipment model.
Recipe/equipment separation is a common pattern; known by everyone who cooks at home. Recipes define the ingredients and steps required to make a final product. In a home kitchen, recipes may define how to make a pizza or bake a cake. The recipes assume the existence of equipment such as mixing bowls, measuring cups, cake pans, and ovens. The recipes specify how to use the equipment, such as beating the eggs for 50 strokes, or heating the oven to 300 F, but they don't specify how that action is performed. The equipment capability defines how the action is performed, such as mixing using an electric mixer or a hand mixer, or heating using gas or electricity. The same cake recipe can be executed in any kitchen that has the right equipment capability.
The ISA 88 standard takes this same general concept and formalizes it for industrial use, as shown in Figure 3-1. The S88 Design Pattern defines two elements a structure for the information within a recipe, and a structure to describe the capabilities of the equipment. When these two structures work together, they provide a simple method for...
