Arc Tangent (ATAN)

When enabled, the ATAN instruction computes the arc tangent of the Source value and stores the result in the Destination (in radians).
The ATAN operator/function computes the arc tangent of the Source and returns the floating point result. The resulting value in the Destination is greater than or equal to -pi/2 and less than or equal to pi/2 (where pi = 3.141593).
Available Languages
Ladder Diagram
ATAN ladder instruction
Structured Text
This instruction is not available in structured text. However, in the Structured Text Editor you can use ATAN 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.
FactoryTalk Design Studio
DSL - Ladder Diagram
Operands
IMPORTANT: Unexpected operation may occur if:
  • Output tag operands are overwritten
  • Members of a structure operand are overwritten
  • Except when specified, structure operands are shared by multiple instructions.
There are data conversion rules for mixing numeric data types within an instruction. See Data conversions.
Ladder Diagram
Operand
Data Type
Format
Description
Source
SINT
INT
DINT
LINT
USINT
UINT
UDINT
ULINT
REAL
LREAL
Immediate
tag
Value to convert to arc tangent.
Destination
SINT
INT
DINT
LINT
USINT
UINT
UDINT
ULINT
REAL
LREAL
tag
Tag to store the result of the instruction.
Operator Aspects
The ATAN operator can be used in various RLL expressions. ATAN returns a floating point result containing the arc tangent of the Source. Depending on the context this value may 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 = arc tangent value of the Source.
Postscan
N/A
Example
Ladder Diagram
ATAN ladder example
Structured Text
REAL_dest := ATAN(REAL_src);
Provide Feedback
Have questions or feedback about this documentation? Please submit your feedback here.
Normal