Short summary

Name	`ATAN2`
→POU type	→function
Category	IEC-block, Numeric
Conform to →IEC-standard	no restrictions
Graphical interface
Available since	version 1.18.0 (for logi.CAD 3) – initial variant: inputs `IN1` and `IN2` version 1.58.0 (for logi.CAD 3) – enhancement: names of inputs changed to `Y` und `X` version 3.1.0 (for library `Standard`) – For inputs of data type `REAL`, the optimized `float` variant of the C-runtime is used. Compared to previous versions , it is possible that (marginal) other results are returned within the threshold range of the block.

Functionality

The trigonometric function arctan is called: The block calculates the arc tangent with 2 parameters. In contrast to the ATAN block, this block observes the sign of both parameters and determines the quadrant of the result .

The return value of the block is the angle in the Cartesian plane between the X-axis and a vector that is pointing from the origin (0,0) to the point (X,Y). The block returns the result in radians, in the range of -PI to +PI (including). The angle is positive for counter-clockwise angles (upper halfplane, Y > 0) and negative for clockwise angles (lower half-plane, Y < 0).

Inputs, return value

	Identifier	→Data type	Description
Inputs:	`Y`	`REAL`, `LREAL` (corresponds to →generic data type `ANY_REAL`)	Y-coordinate
Inputs:	`X`	`REAL`, `LREAL` (corresponds to →generic data type `ANY_REAL`)	X-coordinate
Return value:	–	`REAL`, `LREAL` (corresponds to →generic data type `ANY_REAL`)

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

See:

"Blocks for safe logic" whether this block is supported for developing safety-relevant applications.
"Highlighting safe logic in the FBD-editor" for the effects when using the block as a block for safe logic .

Example for usage within ST-editor

PROGRAM Test
   VAR
      result : REAL;
   END_VAR
   result := ATAN2(Y := 1000.0, X := 50.0);    (* The variable 'result' evaluates to '1.520838'. *)
END_PROGRAM

When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.