Two-Argument Arctangent (ATAN2)

The ATAN2 instruction takes the two-argument arc tangent of the Source values and stores the result in the Destination (in radians). The ATAN2 operator/function computes the arc tangent of the Source and returns the FLOAT result. The resulting value in the Destination is greater than or equal to -p and less than or equal to p (where p = 3.141593).

Available Languages

Ladder Diagram

Structured Text

This instruction is not available in structured text. However, in the Structured Text Editor you can use ATAN2 as an operator in an expression to compute the same result. Refer to Structured Text syntax for more information on the syntax of expressions and assignments within structured text.

Operand	Data Type	Format	Description
Source Y	SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL	immediate tag	Source Y of ATAN2 Input
Source X	SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL	immediate tag	Source X of ATAN2 Input
Dest	REAL LREAL	tag	Tag to store result of the instruction.

Operator Aspects

The ATAN2 operator can be used in various RLL expressions. ATAN2 returns a FLOAT result containing the result of two argument arc tangent of the Source Y and Source X. Depending on the context, this value can then be type converted if appropriate.

Affects Math Status Flags

Conditional, see Math status flags.

Major/Minor Faults

None specific to this instruction. See Index through arrays for array-indexing faults.

Execution

Ladder Diagram

Condition/State	Action Taken
Prescan	N/A
Rung-condition-in is false	Set Rung-condition-out to Rung-condition-in.
Rung-condition-in is true	Set Rung-condition-out to Rung-condition-in. Dest = ATAN2(Source Y, Source X)
Postscan	N/A

Example

Ladder Diagram

Structured Text

REAL_dest := ATAN2(REAL_srcY, REAL_srcX);