Glossary term
Watchdog
communicationAdvanced
Also known as
Surveillance time
Definition
Timer on a receiving Group Object: if no telegram is received within the configured window, switches to a safe fallback state. Assumes the sender is in Cyclic Send.
Questions using this term
- In PROFINET, the 'Watchdog Time' of an IO Device is computed as Update Time multiplied by the Reduction Ratio (typically 3 or more); if no cyclic telegram is received within that window, the device drops its outputs to the safe state.13. Network advanced · Watchdog vs. Update Time
- At start-up, the PROFIBUS master sends a Set_Prm to each slave to parameterise it (User_Prm_Data), then a Chk_Cfg to verify the configuration of its modules, and finally Data_Exchange starts the normal cyclic I/O cycle.17. Master operations · Set_Prm
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