PLC & Programming
Scan time
Definition
How long a PLC takes to complete one full cycle of reading inputs, solving the program, writing outputs, and housekeeping.
Typical values run from a few milliseconds to a few tens of milliseconds. What matters is not the number itself but whether it is stable and comfortably under the watchdog setting.
Scan time sets a floor on response: a field contact cannot affect an output faster than roughly one to two scans plus input filter and output switching time.
Also known as: scan cycle, sweep time.
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