Allen-Bradley MicroLogix 1100 Instruction Set Reference Manual

Publication 1763-RM001C-EN-P - October 2009
270 Using Interrupts
STI User Interrupt Executing (UIX)
The UIX (User Interrupt Executing) bit is set whenever the STI mechanism
completes timing and the controller is scanning the STI PFN. The UIX bit
is cleared when the controller completes processing the STI subroutine.
The STI UIX bit can be used in the control program as conditional logic to
detect if an STI interrupt is executing.
STI User Interrupt Enable (UIE)
The UIE (User Interrupt Enable) bit is used to enable or disable STI
subroutine processing. This bit must be set if you want the controller to
process the STI subroutine at the configured time interval.
If you need to restrict when the STI subroutine is processed, clear the UIE
bit. An example of when this is important is if a series of math
calculations need to be processed without interruption. Before the
calculations take place, clear the UIE bit. After the calculations are
complete, set the UIE bit and STI subroutine processing resumes.
STI User Interrupt Lost (UIL)
The UIL (User Interrupt Lost) is a status flag that indicates an interrupt was
lost. The controller can process 1 active and maintain up to 2 pending
user interrupt conditions before it sets the lost bit.
This bit is set by the controller. It is up to the control program to utilize,
track if necessary, and clear the lost condition.
STI Error Code
Error
Code
Recoverable Fault
(Controller)
Description
1 Invalid Program File
Number
Program file number is less than 3, greater than 255, or does not
exist.
Sub-Element Description Address Data Format Type User Program
Access
UIX - User Interrupt Executing STI:0/UIX binary (bit) status read only
Sub-Element Description Address Data Format Type User Program
Access
UIE - User Interrupt Enable STI:0/UIE binary (bit) control read/write
Sub-Element Description Address Data Format Type User Program
Access
UIL - User Interrupt Lost STI:0/UIL binary (bit) status read/write
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Allen-Bradley MicroLogix 1100 Specifications

General

Processor	32-bit
Programming Software	RSLogix 500
Mounting	DIN rail or panel mount
Power Supply	24V DC
Type	Compact PLC
Digital Inputs	12
Digital Outputs	8
Analog Inputs	4 (depending on model)
Analog Outputs	Optional with expansion module
Programming Language	Ladder Logic
Operating Temperature	0 to 55 °C (32 to 131 °F)
Series	MicroLogix