Input Variable And Output variable

Input Variable

This variable shows the effect of the surroundings on the process. It normally refers to those factors that influence the process. An example of this would be the flow rate of the steam through a heat exchanger that would change the amount of energy put into the process. There are effects of the surrounding that are controllable and some that are not. These are broken down into two types of inputs.

• Manipulated inputs

• Disturbances

Manipulated inputs:- variable in the surroundings can be control by an operator or the control system in place. 
Disturbances:- inputs that can not be controlled by an operator or control system. There exist both measurable and immeasurable disturbances.

Output variable

• SISO

• MIMO

Single input-Single Output (SISO):- for one control(output) variable there exist one manipulate (input) variable that is used to affect the process 
Multiple input-multiple output(MIMO):- There are several control (output) variable that are affected by several manipulated (input) variables used in a given process.

Also known as the control variable These are the variables that are process outputs that effect the surroundings. An example of this would be the amount of CO2 gas that comes out of a combustion reaction. These variables may or may not be measured.  As we consider a controls problem. We are able to look at two major control structures.