Functions of Automatic Control:

In any automatic control system, there are the four basic functions that occur are:

1. Measurement

2. Comparison

3. Computation

4. Correction

Within the water tank level control system in the instance above, the level transmitter measures the level inside the tank. A level transmitter sends a signal representing the tank level to the level control device and where it is compared to a desired tank level. A level control device then computes how far to open the supply valve to correct any difference among actual and desired tank levels.