Installation manual

1 Publication 1747-RM001G-EN-P - November 2008
Chapter 11
Understanding Interrupt Routines
This chapter contains general information about interrupt routines and
explains how they function in your logic program. Each interrupt routine
includes:
• an overview.
• programming procedure.
• operational description.
• associated bit description.
In addition, each interrupt routine contains an application example that shows
the interrupt routine in use.
Table 11.1 Interrupt Routine Instructions
Instruction Mnemonic Instruction Name Purpose Page
User Fault Routine Provides the option of preventing a processor shutdown. 11-2
STI Selectable Timed Interrupt Allows you to interrupt the scan of the main program file
automatically, on a periodic basis, to scan a specified
subroutine file.
11-8
STD Selectable Timed Disable Disables STI’s from occurring. 11-16
STE Selectable Timed Enable Enables STI’s to occur. 11-16
STS Selectable Timed Start Sets or changes the file number or setpoint frequency of
the STI routine.
11-17
DII Discrete Input Interrupt Allows the processor to execute a subroutine when the
input bit pattern of a discrete I/O card matches a compare
value that you programmed.
11-18
ISR I/O Interrupt Allows a specialty I/O module to interrupt the normal
processor operating cycle in order to scan a specified
subroutine file.
11-27
IID I/O Interrupt Disable Disables I/O interrupts from occurring. 11-32
IIE I/O Interrupt Enable Enables I/O interrupts to occur. 11-32
RPI Reset Pending Interrupt Aborts a pending I/O Interrupt. 11-34
INT Interrupt Subroutine Optional instruction to identify interrupt subroutines. 11-34