In ladder logic, which type of contact is energized when its input is true or closed?

In ladder logic, which type of contact is energized when its input is true or closed?

• A. XIC
• B. XIO
• C. Memory
• D. Seal-In

Answer: (A)

In ladder logic, the type of contact that conducts when its input is true or closed is the Examin If Closed contact. It is designed to be energized (conducting) exactly when the associated input is on or in a closed state, so the rung will complete and energize the next element only when the input is true. If the input is off, this contact opens and blocks the rung. This differs from the Examin If Open (XIO) contact, which is energized when the input is false, and from Memory or Seal-In elements, which rely on stored states or a latching condition rather than simply reflecting a true input.

In ladder logic, the type of contact that conducts when its input is true or closed is the Examin If Closed contact. It is designed to be energized (conducting) exactly when the associated input is on or in a closed state, so the rung will complete and energize the next element only when the input is true. If the input is off, this contact opens and blocks the rung. This differs from the Examin If Open (XIO) contact, which is energized when the input is false, and from Memory or Seal-In elements, which rely on stored states or a latching condition rather than simply reflecting a true input.