TABLE OF CONTENTS The S88 Automation Design Pattern should be applied to automated equipment to effectively match the previously described recipe/equipment model. The S88 Automation Design Pattern defines three forms of control: coordination control, procedural control, and basic control. These different types of control work together to provide flexible manufacturing control. Some of the coordination is shown in Figure 5-1.
Basic control is dedicated to establishing and maintaining a specific state of equipment or process condition. Basic control may include regulatory control, interlocking, monitoring, exception handling, and discrete or sequential control. Basic control is usually implemented using one of the IEC 61131-3 languages: Ladder Diagram, Instruction List, Function Block Diagram, or Structured Text. Specialized systems may also be programmed using standard computer languages, such as C, C++, C#, or JAVA. Basic control is often implemented in PLC and DCS systems, or in Open Control System (OCS) personal computers (PCs).
Procedural control is step-based sequencing of actions. Procedural control directs equipment-oriented actions to take place in an ordered sequence to carry out some process-oriented task. Within PLC, DCS, and OCS systems, procedural control is often implemented using the IEC 61131-3 Sequential Function Chart (SFC) language, or an equivalent. When SFCs are not available, the sequencing of steps is often programmed using the other IEC 61131-3 languages.
Coordination control manages the resources in process cells, units, and equipment modules. It is a type of control that directs, initiates, and/or modifies the execution of procedural control. It starts control recipe execution, makes...
