## Behavior of normally-open contact under different bits

A normally-open type contact will __________ when its bit is 0 and ________ when its bit is 1:

1. Open, Close
2. Close, Open
3. Open, Open
4. Closed, Close

Explanation: A normally-open type contact will open when its bit is 0 and close when its bit is 1

## Which of the following is correct about contacts or coils seen in a Ladder Diagram PLC

Which of the following is correct about contacts or coils seen in a Ladder Diagram PLC:

1. All contacts and coils are real
2. Contacts are real, while coils are programmed bits
3. Coils are real, while contacts are programmed bits
4. Both coils and contacts are bits in PLC memory

Correct answer: 4. Both coils and contacts are bits in PLC memory

## Each horizontal line Ladder Diagram is referred to as

Each horizontal line Ladder Diagram is referred to as:

1. Period
2. Group
3. Row
4. Rung

Just as each horizontal step on a stepladder is called rung, the horizontal line in the Ladder diagram is referred to as rung.

## When relay coil is energized it is said to be

When relay coil is energized it is said to be:

1. Drop out
2. Roll in
3. Picked up
4. None of the above