Supervisory Control and Data Acquisition

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Animated screen display of a SCADA system

Under Supervisory Control and Data Acquisition ( SCADA ) refers to the monitoring and control of industrial processes by means of a computer system's.

concept

The principle of a SCADA system.

Automations are divided into several layers. This is illustrated by the automation pyramid.

Level 1 is the process-related layer. The term SCADA usually refers to centralized / decentralized systems that monitor , visualize and control and regulate the entire installation . Most of the control is carried out automatically by remote control terminals (RTU) or by programmable logic controllers (PLC) or level 1 automation.

The task of level 2 automation is to optimize the function of level 1 automation and to output manipulated variables and setpoints . Level 3 automation, on the other hand, is used for planning , quality assurance and documentation .

The data acquisition usually starts with level 1 and contains the coupling to measuring devices and status information such as switch positions that are recorded by the SCADA system. The data are then presented in a user-friendly way and make it possible to control the process.

SCADA systems typically implement a distributed database that contains data points. A data point contains an input or output value that is monitored and controlled by the system. A physical data point represents an input or output, while a calculated point is based on the state of the system through mathematical operations . Typically, data points are treated as a combination of values ​​with a time stamp. A series of data points enables the historical evaluation.

communication

The communication within SCADA systems takes place more and more on the basis of TCP -based internet technologies. At the field level, serial connections in the form of point-to-point communications and field bus systems also play an important role, which will probably be maintained for the foreseeable future. The standardization in the communication has not been completed. Attempts such as OPC are often limited to certain operating systems , although here, too, a step has been taken towards operating system independence ( OPC XML-DA , OPC UA ). Manufacturer-specific or closed solutions can often be found in the SCADA area. But open protocols such as Modbus are enjoying increasing popularity. Different transmission protocols can be adapted to one another via gateways in the form of embedded systems . The workplaces at which visualization is performed are increasingly being used today via Ethernet or wireless networks, i.e. H. more and more connected on the basis of TCP.

See also

Web links

Individual evidence

  1. ↑ SCADA screenshots. In: integraxor.com. Ecava IGX Web SCADA, May 18, 2016, accessed on August 5, 2019 (English, Basic Animations).
  2. ↑ Olof Leps: The construction of operating and control systems . In: Hybrid test environments for critical infrastructures . Springer Vieweg, Wiesbaden, 2018, ISBN 978-3-658-22613-8 , pp. 25–39 , doi : 10.1007 / 978-3-658-22614-5_3 ( springer.com [accessed December 30, 2018]).