XIO input in ladder logic is represented by which contact?

XIO input in ladder logic is represented by which contact?

• A. Normally-Closed Pushbutton
• B. Normally-Open Pushbutton
• C. Toggle Switch
• D. Thermostat

Answer: (A)

In ladder logic, XIO means you’re checking the input in its inverted state. That inversion is modeled with a normally closed contact, because a normally closed device is conducting when not actuated and opens when actuated. A normally closed pushbutton will pass the rung when it’s not pressed (input is off) and stop the rung when it’s pressed (input is on). That inverted behavior is exactly what XIO represents: the rung is true when the input is in its open state (or not active) and false when the input is active. A normally open pushbutton would be used with the non-inverted XIC instruction, while a toggle switch or thermostat aren’t the standard contact types used to represent this specific input inversion in ladder logic.

In ladder logic, XIO means you’re checking the input in its inverted state. That inversion is modeled with a normally closed contact, because a normally closed device is conducting when not actuated and opens when actuated. A normally closed pushbutton will pass the rung when it’s not pressed (input is off) and stop the rung when it’s pressed (input is on). That inverted behavior is exactly what XIO represents: the rung is true when the input is in its open state (or not active) and false when the input is active. A normally open pushbutton would be used with the non-inverted XIC instruction, while a toggle switch or thermostat aren’t the standard contact types used to represent this specific input inversion in ladder logic.