Glossary · Automation fundamentals, platforms and components
Time element (timer)
Also known as: Timer, Time-delay element, Time member
German: Zeitglied
In control engineering, a time element (German: Zeitglied) is a function that delays or limits a signal in time. In PLC programming, IEC 61131-3 provides the standard timer function blocks TP (pulse), TON (on-delay) and TOF (off-delay); in relay technology, timing relays serve the same purpose.
- Automation components
In one sentence
A time element delays or limits a signal in time; IEC 61131-3 defines the timer function blocks TP (pulse), TON (on-delay) and TOF (off-delay).
Example
A TON timer with 5 s delays the fault message for low pressure, so short pressure dips while a valve switches do not stop the machine.
How it applies
- Engineering: Timers filter signals, monitor step durations in a Step chain, create pulses and implement delays. Their resolution depends on the task cycle, so a timer in a 10 ms task cannot measure 1 ms precisely.
- Safety: Time delays in safety functions, for example the delay before releasing a guard, must be realized in safety-rated devices or safety PLC code, and chosen based on the machine's Stopping time.
- Documentation: List timer settings that operators or service staff may change, with range, unit and effect. Undocumented timer values are a common reason why machines behave differently after a program change.
Time element vs. control-engineering time behavior
In control theory, "Zeitglied" can also mean a dynamic element with delay behavior, such as a dead-time or first-order element. In PLC and relay contexts, it means a timer. Make the meaning clear in translations.