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Robotics & Automation vocabulary · PLCs and Industrial Control

Scan cycle

Meaning in robotics & automation, with examples

/ˈskæn ˌsaɪkəl/nounCommon term

In robotics & automation, scan cycle means: The repeating loop a PLC runs: it reads all inputs, executes the program from top to bottom, then updates the outputs. The time one loop takes is the scan time.

In Turkish: tarama çevrimi, tarama döngüsü, PLC çevrimi

How it is used

Important for understanding PLC behavior and timing. Scan times are usually a few milliseconds, and long code or heavy communication makes them longer. Very short signals can be missed between scans, so fast inputs may need interrupts or high-speed counters.

Example sentences

  1. The pulse is shorter than one scan cycle, so the PLC sometimes misses it.

  2. After we added the new logging code, the scan cycle went from 4 ms to 11 ms.

Common collocations

  • scan time
  • PLC scan
  • per scan
  • watchdog time
  • first scan
  • PLCShort for programmable logic controller: a rugged industrial computer that reads inputs from sensors and switches, runs a control program and drives outputs such as motors, valves and lamps.
  • ladder logicA graphical PLC programming language that looks like an electrical relay diagram, with contacts and coils placed on horizontal lines called rungs between two vertical rails.
  • I/OShort for inputs and outputs: the signals a controller receives from sensors and buttons, and the signals it sends to valves, motors, lamps and other devices.
  • cycle timeThe time a machine, robot or station needs to complete one full cycle of its task, for example from picking one part to being ready to pick the next.

More terms: PLCs and Industrial Control

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