Glossary · System coordination, integration and orchestration
Global time base
Also known as: common time base, system-wide time reference
German: Globale Zeitbasis
In distributed automation systems, a global time base is a common time reference to which the clocks of all participating devices are synchronized, for example via the Precision Time Protocol (IEEE 1588) or NTP, so that timestamps and time-triggered actions are comparable across devices.
- System integration
In one sentence
A global time base is a common time reference that all devices synchronize to, making timestamps and timed actions comparable across devices.
Example
All protection relays and PLCs of a substation synchronize to a PTP grandmaster clock, so the sequence of events across devices can be reconstructed to the millisecond.
How it applies
- Engineering: Choose the synchronization method by required accuracy: NTP is typically sufficient for logging, while motion control and power systems often need PTP or bus-specific mechanisms. Define the time source, its redundancy and the time zone convention (UTC is recommended for storage).
- Operation: Monitor synchronization status. Devices that lose synchronization drift, and their timestamps silently become misleading.
- Documentation: System documentation should name the time source, the expected accuracy and how devices react to loss of synchronization. Event logs shown to users should state the time zone.
Global time base vs. distributed clock
The global time base is the shared reference time. A Distributed clock is one mechanism that makes local device clocks follow such a reference within a network segment.