Glossary · Automation fundamentals, platforms and components
Delay
Also known as: Time delay
German: Verzögerung
In automation, a delay is a deliberate or inherent time interval between a cause and its effect, such as a programmed timer between a signal and an output, or the time a signal needs to pass through a system.
- Automation components
In one sentence
A delay is a time interval between a cause and its effect, either programmed with a timer or inherent in the system.
Example
The fan continues to run for 60 s after the heater switches off, implemented as an off-delay timer.
How it applies
- Engineering: Programmed delays filter signal bounce, sequence actions or let equipment cool down. IEC 61131-3 defines timer function blocks such as TON (on-delay), TOF (off-delay) and TP (pulse).
- Safety: Delays add to response and stopping times. Safety-related delays, such as in Stop category 1, must be included in the calculation of the safety distance.
- Documentation: Describe noticeable delays in operating instructions, especially when a machine keeps moving or restarts after a waiting time. Unexpected delayed movement is a hazard.
Delay vs. dead time vs. latency
"Delay" is the general term. Dead time is the control engineering term for a delay in the process response. Latency describes delays in communication and data processing.