AUTOMATION AND ROBOTICSLAB NO.03Question 01:The AND Gate: The AND gate is associated with the following symbol that can have any number of inputs but only one output.

The truth table below shows that the output is only turned on when all the inputs are true (1). An easy way to remember this is AND works like multiplication.

Input AInput BOutput

000

100

010

111

The ladder logic equivalent for an AND function looks like two normal contacts side by side.

Question 02:The OR Gate:Last but not least the OR gate is associated with the following symbol that also can have any number of inputs but only one output.

The truth table below shows that the output is turned on (1) when any of the inputs are true (1). An easy way to remember this is OR works like addition.Input AInput BOutput

000

101

011

111

The ladder logic equivalent for an OR function looks like two normal contacts on top of each other.

Practice Problem:Consider a water tank that is initially full, which has two input sensors and one output. When below sensor A sense the water level, motor on automatically and sensor A off. When tank is full sensor B sense the water level and off the motor.

Solution:As initially water tank is full, sensor I 0.4 is on. When tank become empty another sensor I 0.5 sense the water level and on the motor and after that sensor I 0.5 off but still motor is on until water tank become full. When tank is full sensor I 0.4 sense the water level and off the motor.