ATAN

Calculates the arc tangent of Value and stores the result in Angle.

Ladder Representation

Block Structure

Variable Type	Name	Data Type	Description
VAR_INPUT	EN	BOOL	Block enabling.
VAR_INPUT	Value	REAL	Tangent value.
VAR_OUTPUT	Done	BOOL	End of operation.
VAR_OUTPUT	Angle	REAL	Angle whose tangent equals Value, in radians.

Operation

When EN is TRUE, the block writes the arc tangent of Value to Angle.

If the operation completes without errors, Done is set. If an operation error occurs, Done remains FALSE and Angle keeps its previous value.

When EN is FALSE, Angle remains unchanged and Done remains FALSE.

Execution Flowchart

Examples

Ladder Example

This example calculates the angle, in radians, whose tangent is VALUE, and stores the final result in ANGLE. For positive values, the angle is always in the first quadrant. The block completes successfully and activates Done.

This example calculates the angle, in radians, whose tangent is VALUE, and stores the final result in ANGLE. For negative values, the angle is always in the fourth quadrant. The block completes successfully and activates Done.

Structured Text Example

The following Structured Text code applies the same logic shown in the Ladder example.

Structured Text

VAR
    VALUE : REAL := -1.0;
    ANGLE : REAL;
END_VAR

ANGLE := FB_ATAN(EN:=DI1, Value:=VALUE, Done=>DO1);