Glossary · Functional safety
Control system
Also known as: machine control system
In machine engineering, a control system is the combination of components and logic that commands, regulates, and monitors machine behavior. It includes input devices, logic such as PLCs, and output devices such as contactors, valves and drives.
- Functional safety
- Integrated systems
In one sentence
A control system combines sensors, logic and actuators to command and monitor a machine; only some of its parts are safety-related.
Example
The control system of a packaging line includes the operator panel, a PLC that sequences the stations, frequency converters on the conveyors and a separate safety PLC for the guard interlocks.
How it applies
- Functional safety: Only the safety-related parts are designed to a PL or SIL. The rest of the control system must not be able to override or impair them.
- Integrated systems: When machines are linked, their control systems exchange signals. Define which signals are safety-related and which are only operational.
- Technical documentation: Circuit diagrams, I/O lists and the description of operating modes belong in the technical documentation. Electrical design follows IEC 60204-1.
- Change control: Software updates to the standard control system can still affect safety, for example by changing sequences or speeds. Assess them under change control.
Control system vs. safety-related part
The control system is the whole. The safety-related part is the portion that performs safety functions and receives the design, verification and validation effort of ISO 13849-1 or IEC 62061.