What is the batch process?
A process that leads to the production of finite quantities of material by subjecting the quantities of input materials to an ordered set of processing activities over a finite period of time using one or more equipment.
The PCB (Process Control Block) is a special register where the operating system groups all the information you need to know about a particular process. Each time a process is created, the operating system creates the corresponding BCP to serve as a description at runtime throughout the life of the process. When the process ends, your BCP is deleted and the record can be used for other processes.
Also read: How does a process control work?
The information stored in a BCP typically includes some or all of the following fields:
- Process Identifier (PID- of its acronym in English).
- Process status. For ex. ready, waiting, blocked.
- Program Counter: Address of the next instruction to execute.
- CPU registration values. They are also used in the context change.
- Memory address space
- Priority in case of using said algorithm for CPU planning.
- List of assigned resources (including file descriptors and open sockets).
- Statistics of the process.
- Data of the owner (owner).
- Assigned permissions.
- Signals pending of being served. (Stored in a bitmap)
What is ISA S88?
The purpose of the ISA S88 (Also IEC 61512-01 standard) standard was to emphasize good practices for the design and operation of batch manufacturing plants and to improve control of batch manufacturing plants.
The standard consists of three parts that each has its own specific subjects, but they are closely related. Part one (published in 1995) consists of a consistent set of models and terminology concerning batch processes. Part two (published in 2000) consists of data structures and a graphical method for depicting recipes (PFC). Part three is about General and Site recipes.
S88.01 is a model and methodology for designing & operating control systems for flexible manufacturing, which is:
- Independent of the underlying control system (PLC, DCS, or PC)
- Independent of the underlying basic control algorithms
- Flexible manufacturing (including batch)
- Multiple products manufactured using the same set of equipment
- Output is a finite quantity of materials
- Built using a defined order of processing actions
Advantages of ISA S88:
Prevention of failures and weaknesses in batch control
Improvement of communication with suppliers and system integrators
Possibility of reuse, so less time is needed
Become independent of suppliers
Improvement of through put per process cell
Bring new products to the market faster and more easily
Simplification of recipe development
Recipes become flexible and reusable
The control system can be maintained more easily
Capacity usage can be optimised
Quality control can be improved