Glossary · System coordination, integration and orchestration
Heartbeat
Also known as: heartbeat signal, keep-alive signal, life sign
German: Heartbeat
In automation and distributed systems, a heartbeat is a periodic signal or message that a system sends to show that it is running and able to communicate, for example a toggling bit, an incrementing counter or a keep-alive message.
- System integration
In one sentence
A heartbeat is a periodic signal, such as a toggling bit or counter, by which a system shows that it is running and communicating.
Example
The line controller increments a heartbeat counter every 500 ms; each machine checks that the value changes and stops feeding product if it hasn't changed for two seconds.
How it applies
- Engineering: Use a counter or toggling value, not a constant “OK” bit, so that a frozen sender or frozen communication is detectable. Fieldbuses such as CANopen define their own heartbeat mechanisms.
- Design: Choose the heartbeat period and detection time together; the receiver typically tolerates a few missed heartbeats to avoid false alarms.
- Documentation: List heartbeat signals in the interface specification with their period, the detection time and the reaction of each partner. Operators should see a clear message naming the partner that stopped responding.
Heartbeat vs. watchdog
A heartbeat is sent by a system to others. A watchdog is a local timer inside a device that must be retriggered by its own software. Both detect stalls, but at different places.