Safe state
The predefined condition a safety function drives a machine or process into when it detects a hazard or a fault; on most machines, de-energized outputs.
The network analogy
Fail-closed behavior. When the system cannot trust its inputs or its link, it falls back to a condition chosen in advance instead of holding the last value.
Why it matters for wireless
A safety connection that times out over wireless puts its data into the safe state, which on a machine usually means a stop. Each nuisance timeout from a slow roam is a stop the operation has to recover from.
NIST describes safety systems as reducing hazards by bringing the system to a safe state. One vendor’s safety controllers are approved for applications where the de-energized state is considered to be the safe state, and a safety connection that misses its limit places its I/O data in the safe state (Off). ODVA lists ensuring that failures always lead to a safe state among the common themes of functional safety.
What the safe state is comes from the hazard analysis, not from the network. The network only decides how often a timeout sends the system there.
About this page
Built from 4 sources: 2 standards bodies and labs, 1 protocol owner or alliance and 1 vendor document. Researched and drafted with AI assistance, then reviewed and approved by Ben Rutter on . How pages are made
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Cite this page
Plain
Ben Rutter. "Safe state." OT Wireless, published October 5, 2026. https://otwireless.com/glossary/safe-state/
APA 7
Rutter, B. (2026, October 5). Safe state. OT Wireless. https://otwireless.com/glossary/safe-state/
BibTeX
@misc{rutter2026safestate,
author = {Rutter, Ben},
title = {{Safe state}},
year = {2026},
howpublished = {\url{https://otwireless.com/glossary/safe-state/}},
organization = {OT Wireless},
}