Glossary · Requirements and interfaces
Hardware requirement
German: Hardwareanforderung
In systems engineering, a hardware requirement is a requirement allocated to a hardware element, stating a physical, electrical, mechanical or environmental characteristic it must have, such as supply voltage, I/O count, protection rating, temperature range or response time.
- Systems engineering
In one sentence
A hardware requirement states what a hardware element must provide, such as voltage, I/O count, protection rating or temperature range.
Example
The control cabinet must operate between 5 °C and 45 °C, provide 64 digital inputs and meet IP54.
How it applies
- Engineering: Hardware requirements are derived from System requirements and allocated to cabinets, controllers, sensors and drives.
- Functional safety: For safety functions, hardware requirements include architecture, diagnostics and reliability figures used for Performance Level (PL) or Safety Integrity Level (SIL) calculations.
- Documentation: Technical data tables, installation conditions and ambient limits in the manual should come from the verified hardware requirements, not from a datasheet copied at an earlier stage.
- Verification: Each hardware requirement needs a Verification method: inspection of the parts list, type test certificates, or measurement during the factory acceptance test.
Hardware requirement vs. software requirement
A hardware requirement constrains physical elements; a Software requirement constrains program behavior. Many functions need both, and the Interface requirement between them (signals, timing, ranges) is where errors often hide.