Arc Tangent (ATAN)
This table lists the controllers and applications that support this instruction.
Architecture | Standard applications | Safety applications |
|---|---|---|
CompactLogix 5370, ControlLogix 5570, Compact GuardLogix 5370, and GuardLogix 5570 controllers | Yes | No |
CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers | Yes | Yes |
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).
TIP:
In Logix Designer version 36, the mnemonic for this instruction changed from ATN to ATAN.
Available Languages
Ladder Diagram
Function Block Diagram
Function Block Diagram supports these elements:
FBD Block
FBD Function
Structured Text
This instruction is not available in structured text.
TIP:
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.
Ladder Diagram
Operand | Data Type CompactLogix 5370, ControlLogix 5570, Compact GuardLogix 5370, and GuardLogix 5570 controllers | Data Type CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers | Format | Description |
Source | SINT INT DINT REAL | SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL | Immediate tag | Value to convert to arc tangent. |
Destination | SINT INT DINT REAL | SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL | tag | Tag to store the result of the instruction. |
Function Block Diagram
Function Block
Operand | Type | Format | Description |
ATAN tag | FBD_MATH_ADVANCED | tag | ATAN structure |
FBD_MATH_ADVANCED Structure
Input Member | Data Type | Description |
EnableIn | BOOL | Enable input. If false, the instruction does not execute and outputs are not updated.
Default is true. |
Source | REAL | Input to the trigonometric instruction. |
Output Member | Data Type | Description |
EnableOut | BOOL | Indicates if the instruction executed without fault when it was enabled. |
Dest | REAL | Result of the instruction. |
FBD Function
TIP:
FBD Function is applicable to CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers only.
Operand | Data Type CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers | Description |
Source | SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL | Value to convert to arc tangent. |
Output Operand (Right Pin) | Data Type CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers | Description |
Dest | REAL LREAL | Result of the function. |
See FBD Functions.
Operator Aspects
The ATAN operator can be used in various RLL expressions. Similarly, the ATAN function is invoked in Structured Text statements. 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
Controllers | Affects Math Status Flag |
CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers | Conditional, see Math Status Flags. |
CompactLogix 5370, ControlLogix 5570, Compact GuardLogix 5370, and GuardLogix 5570 controllers | Yes |
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 |
Function Block Diagram
FBD Block
Condition/State | Action Taken |
Prescan | N/A |
EnableIn is false | Set EnableOut to EnableIn. |
EnableIn is true | Dest = arc tangent value of the Source. If overflow occurs Clear EnableOut to false. else Set EnableOut to true. |
Instruction first scan | N/A |
Instruction first run | N/A |
Postscan | N/A |
FBD Function
TIP:
FBD Function is applicable to CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers only.
Condition/State | Action Taken |
Prescan | N/A |
Normal Scan | Dest = arc tangent value of the Source. |
Instruction first run | N/A |
Instruction first scan | N/A |
Postscan | N/A |
Example
Ladder Diagram
Function Block Diagram
FBD Block
FBD Function
Structured Text
REAL_dest := ATAN(REAL_src);
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