Hello!

i am new with programming so i'm asking maybe stupid questions, so if i have analog input what gives value from 400 to 1000. Value 400 is for example 80 cm and 1000 is 1100cm. How i can make a program which tells automatically how many cm is value 500?Hope somebody understand this...

thanks

Originally created by: scott_cunningham

This is a linear equation of style y = ax + b. I will leave you to fill in the blanks on the equation details.

So create a FUNCTION - but you first need to decide your data type. INT or REAL... You are using nice rounded numbers, so I will pick INT (using ST language):

FUNCTION GetDistance : INT
VAR_INPUT
   Raw : INT;
END_VAR
VAR CONSTANT
   SCALE: INT := 123;
   OFFSET: INT := 123;
END_VAR
GetDistance := Raw * SCALE + OFFSET;
END_FUNCTION

Then in your regular program you can simply write:

Cm := GetDistance(500);

HINT: Always make sure you don't overflow the data type! INT only goes to +32767.