Cycle time
The period of a repeating control activity, such as one execution of a controller task or one round of cyclic I/O exchange on the network.
The network analogy
A scheduler tick. Work happens once per tick, so an input that changes just after a tick waits for the next one.
Why it matters for wireless
Every cycle that crosses a radio picks up delay that varies from cycle to cycle. The application tolerates only so many late or missing cycles before it faults, so the wireless worst case has to be measured against the cycle, not against an average.
The range is wide. NIST describes plant control loops with cycle times from milliseconds to minutes. PROFINET exchanges cyclic data at update times from 250 µs to 512 ms1, and its isochronous class can go as low as 31.25 µs. Inside a controller, one vendor defines its safety task period as the interval between successive executions of the safety task, and its worked example counts a full period because the scan may have just ended when the input changed.
Production people use the same words for something else: the time required to produce a part or complete a process. When someone quotes a cycle time, ask whether they mean the controller, the network, or the part.
About this page
Built from 5 sources: 1 standards body or lab, 1 protocol owner or alliance, 2 vendor documents and 1 other source. 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. "Cycle time." OT Wireless, published October 5, 2026. https://otwireless.com/glossary/cycle-time/
APA 7
Rutter, B. (2026, October 5). Cycle time. OT Wireless. https://otwireless.com/glossary/cycle-time/
BibTeX
@misc{rutter2026cycletime,
author = {Rutter, Ben},
title = {{Cycle time}},
year = {2026},
howpublished = {\url{https://otwireless.com/glossary/cycle-time/}},
organization = {OT Wireless},
}