Process computing technology

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The term process computer technology was used to describe the structure, configuration and programming of minicomputers for the practical control and regulation of industrial processes. Due to the progressive miniaturization of computers and the associated more diverse possible uses, this term is understood today to mean the construction of reactive real-time systems in the broadest sense. Process control technology and control technology are special disciplines in process computer technology.

Basics

Processes of a physical or chemical nature generally run autonomously. In the production environment, for example, it should be possible to influence these processes in such a way that, for example, they are started or stopped at certain times or, through a uniform sequence, produce a predetermined and desired result. If this is not achieved manually, but with the help of programmable control systems, then one speaks of process computing technology. It interacts with the running process using sensors and actuators , and all interventions and measures must take place within a deterministically defined period of time, i.e. in real time . In contrast to normal measurement and control technology, these control systems are programmable and can therefore be changed and adapted without exchanging control units .

Another area of ​​application of process computer technology is the control and regulation of non-deterministic processes. These are characterized by events and associated control tasks, the occurrence of which can at most be named according to probability but does not occur at predetermined or expected times. Examples are large, distributed telecommunication networks or energy supply facilities for residential developments as well as all processes that are carried out by people. In particular, people are to be viewed as autonomously running processes, even if action is to be guided in predeterminable paths through rules and regulations.

Since process computing technology has a direct influence on the external autonomous processes through the actuators , it and the controlled system must also meet special requirements for fault tolerance and fail-safe technology.

Embedded systems are typical representatives of process computing technology.

history

In the sixties, the minicomputer was introduced and was suitable as a replacement for the module assemblies that had been common up until then. If the modules had to be wired according to the desired functions and were therefore difficult to adapt to new requirements, the minicomputers with the associated input / output modules could be flexibly adapted. The introduction was often an economic aspect. Despite the high acquisition costs for minicomputers, these were superior in terms of adaptability and expandability. The company DEC was able to set standards in the field of process computing technology with the mini computers PDP-8 and PDP-11 .

Miniaturization and the drop in prices in the field of computers and microprocessors allowed the increasing use of process computing technology in smaller systems and facilities. At the same time, the scope of process computing technology grew. Today, despite their common origins, a distinction is made between process control systems and embedded systems. While process control systems are their own self-contained systems such as PLC or host-based, embedded systems are often produced with the help of fully integrated microcontrollers .

application

A simple task for control engineering is, for example, the flow control of liquid in a pipe. This can be solved by using a flow rate transmitter (sensor), a slide (actuator), a setpoint specification and a comparator (controller). But if other influences are added that have an impact on the flow, such as pressure and temperature, the control loop becomes more complex. Adjustments take more time. Process computers can solve this task more flexibly and, in the case of complex applications, often more cheaply.

features

Due to the increasing use of computers in all areas of application, the typical boundaries to process computing are becoming blurred. But the following features are still typical of process computers:

  • Sensors
  • Actuators
  • deterministic real-time behavior
  • Integration into external processes and systems
  • Influence on external and autonomous processes

literature

  • Georg Färber: Process computing technology. Basics, hardware, real-time behavior. 3rd, revised. Ed., Springer, Berlin 1994 ISBN 3-540-58029-8