Example

This chapter shows an example for calculating an angle of inclination in a PLC program.

Requirement: the inclination measurement was configured as described in chapter Calculation in the controller.

Variable links in TwinCAT

• "AI Inputs Channel 1" > "Value" is linked to ay
• "AI Inputs Channel 2" > "Value" is linked to ax
• "AI Inputs Channel 3" > "Value" is linked to az

Program code

PROGRAM MAIN
VAR
  ax AT %I*     : INT;
  ay AT %I*     : INT;
  az AT %I*     : INT;
  Inclincation  : LREAL;
END_VAR


IF (ay <> 0 OR az <> 0) THEN        (* Prevent division by 0 *)
  Inclincation := ATAN( ax / SQRT( ay * ay + az * az ) ) * 360 / ( 2 * 3.14 );
END_IF

(* Compensate zero crossing of az *)
IF az > 0 THEN                        
  Inclincation := 180 - Inclincation;
END_IF

(* Insert offset to shift the measuring range from -90...270 to -180...+180 *)
IF Inclincation > 180 THEN                 
  Inclincation := Inclincation - 360;
END_IF