Motor controlsQuestion 30 of 1506

The ladder program shown on a computer screen for a PLC contains contacts and coils. What are they?

  1. Software commands, not real contacts and coils
  2. Real relays inside the PLC housing
  3. Small contactors inside the output modules
  4. Thermal elements that mimic a relay
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Correct answer: Software commands, not real contacts and coils

They are virtual. There are no real contacts or coils operating inside the PLC.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 6.6: Programmable Logic Controllers (PLC)

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Questions last reviewed: 18 October 2026