Allen-Bradley LOGIX 5000

Chapter 4
Select_Limit Instructions
360 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Structured Text
Operand Type Format Description
HLL tag HL_LIMIT structure HLL structure
See Structured Text Syntax for more information on the syntax of expressions
within structured text.
Description
The HLL instruction determines the value of the Out using these rules:
Selection Condition Action
SelectLimit = 0
(use high and low limits)
In < HighLimit and
In > LowLimit
Out = In
In HighLimit Out = HighLimit
In LowLimit Out = LowLimit
HighLimit LowLimit Out = LowLimit
SelectLimit = 1
(use high limit only)
In < HighLimit Out = In
In HighLimit Out = HighLimit
SelectLimit = 2
(use low limit only)
In > LowLimit Out = In
In LowLimit Out = LowLimit
Affects Math Status Flags
No
Major/Minor Faults
None specific to this instruction. See Common Attributes for operand-related
faults.
Execution
Function Block
Condition/State Action Taken
Prescan EnableIn and EnableOut bits are cleared to false.
Tag.EnableIn is false EnableIn and EnableOut bits are cleared to false.
Tag.EnableIn is true EnableIn and EnableOut bits are set to true.
The instruction executes.
Instruction first run N/A
Instruction first scan N/A
Postscan EnableIn and EnableOut bits are cleared to false.