Output Latch (OTL)

Output Latch (OTL)

This information applies to the
CompactLogix
 5370,
ControlLogix
 5570,
Compact GuardLogix
 5370,
GuardLogix
 5570,
Compact GuardLogix
 5380,
CompactLogix
 5380,
CompactLogix
 5480,
ControlLogix
 5580, and
GuardLogix
 5580 controllers.
The Output Latch (OTL) instruction sets (latches) the data bit.
When the rung condition is true, the OTL instruction sets the data bit to true. The data bit remains true until it is cleared, typically by an OTU instruction. When the rung condition is changed to false, the OTL instruction does not change the status of the data bit.
Available Languages
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.
Ladder Diagram
Operand
Data Type
Format
Description
Data bit
BOOL
tag
Bit to be modified. There are various operand addressing modes possible for the data bit, see Bit Addressing for examples.
Affects Math Status Flags
No
Major/Minor Faults
None specific to this instruction. See Index through arrays for array-indexing faults.
If the operand is an indirect array reference and the subscript is out of range, then the controller does not generate a major fault when the OTL instruction is false.
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.
The data bit is set to true.
Postscan
N/A
Example
Ladder Diagram
When enabled, the OTL instruction turns the light on.
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