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A process control block (PCB), also sometimes called a process descriptor, is a data structure used by a computer operating system to store all the information about a process. When a process is created (initialized or installed), the operating system creates a corresponding process control block, which specifies and tracks the process state (i ...
A control loop is the fundamental building block of control systems in general and industrial control systems in particular. It consists of the process sensor, the controller function, and the final control element (FCE) which controls the process necessary to automatically adjust the value of a measured process variable (PV) to equal the value of a desired set-point (SP).
The process state includes all the registers that the process may be using, especially the program counter, plus any other operating system specific data that may be necessary. This is usually stored in a data structure called a process control block (PCB) or switchframe .
As it is there is use made in systems biology of the block diagram technique harnessed by control engineering [7] where the latter is itself an application of control theory. An example of this is the function block diagram, one of five programming languages defined in part 3 of the IEC 61131 (see IEC 61131-3) standard that is highly formalized ...
Each process in the system is represented by a data structure called a Process Control Block (PCB), or Process Descriptor in Linux. Process Identification: Each process is uniquely identified by the user's identification and a pointer connecting it to its descriptor.
The distinguishing feature of the PID controller is the ability to use the three control terms of proportional, integral and derivative influence on the controller output to apply accurate and optimal control. The block diagram on the right shows the principles of how these terms are generated and applied.
For example, a process may block on a call to an I/O device such as a printer, if the printer is not available. Processes also commonly block when they require user input, or require access to a critical section which must be executed atomically. Such critical sections are protected using a synchronization object such as a semaphore or mutex.
Example of a "performance seeking" control-flow diagram. [1] A control-flow diagram (CFD) is a diagram to describe the control flow of a business process, process or review. Control-flow diagrams were developed in the 1950s, and are widely used in multiple engineering disciplines.