Link programmed control
The connection-programmed control (VPS) ( hard-wired programmed logic controller ; also hard-wired control or hard-wired logic or conventional control ) is a possibility to implement control and regulation tasks in process and automation technology. The term connection-programmed controller (VPS) was introduced in order to be able to distinguish it from the programmable logic controller (PLC).
species
In contrast to the programmable logic controller (PLC), the switching logic is determined by the fixed connection of the individual components. The permanent connection can be the wiring of logical components ( relay contacts , coils), special logic modules (e.g. BBC Sigmatronic modules) or the printed circuit of a circuit board . The respective task of the control determines how the components, e.g. B. relays, contactors , switches , multifunction relays, light barriers , display devices are to be connected to each other. If the control task changes, the wiring, but often the assembly with components, must be changed.
use
In earlier times, the control from the control level to the cell level was designed in VPS. The wiring effort was enormous, and troubleshooting was very tedious. Furthermore, complex control systems of this type were very error-prone, since a broken wire or faulty wiring could lead to partial or total failure of the system.
Connection-programmed controllers lost more and more of their importance with the development of the programmable logic controller (PLC). In the meantime, PLC systems have almost completely replaced those based on VPS. The use of a PLC makes the control more flexible and the wiring effort is drastically reduced. In addition, bus systems / fieldbuses such as AS-i , Profibus , EtherCat , SERCOS III and many more are used nowadays , which further optimize the maintainability, planning, configuration and, last but not least, the flexibility of a control system and at the same time further reduce the wiring effort.
A signal-processing part is required to route the signals from the sensors to the respective actuators. With VPS, these are often relays, contactors, timers or FPGAs . In the case of a PLC, this is implemented by an electronic processor that processes an application program, the design of which determines the linking of the inputs and outputs but can also take on various other functions.
However, certain safety-relevant functions (e.g. emergency stop ) must also work if the PLC fails. The VPS is therefore mainly used today as a supplement to the PLC, so that the safety of a machine or system is guaranteed even in the event of a PLC malfunction (e.g. system crash). However, so-called fail-safe controls and bus systems such as PROFIsafe or Safety-over-EtherCat are now also used here .
Individual evidence
- ^ A b Alfred Böge (ed.): The Technician Handbook , Vieweg, Braunschweig a. Wiesbaden, 1999, p. 1656, ISBN 3-528-34053-3
- ↑ W. Beitz, K.-H. Grote (ed.): Dubbel , paperback for mechanical engineering, Springer, Berlin a. Heidelberg, 1997, p. T37
- ^ Karl Heinz Fasol: binary control technology , Springer, Berlin a. Heidelberg, 1988, p. 4 ff., ISBN 978-3-540-50026-1