Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 263)

1 Publication 1785-UM012D-EN-P - July 2005
Chapter
18
Using Processor Input Interrupts
Using This Chapter
Using a Processor Input
Interrupt A processor input interrupt (PII) specifies when an event-driven input causes
the controller to interrupt program execution and run a PII program file once
to completion. Afterwards, the controller resumes executing the program file
from where it was interrupted. Use PIIs only for inputs in the
controller-resident chassis.
You can use a processor input interrupt (PII) as an event-driven interrupt or in
high-speed processing applications. For example, you may need to count
inputs quickly to track production, such as in a canning line. Or, use a PII if
your application calls for an immediate input update when a part is seen on a
conveyor and you need to do an immediate output update to perform the next
action. For example, when a part moving down a conveyor line is detected,
you may need to stop it so the next piece can be added.
Your PII program can contain immediate update instructions to complete
high-speed control functions. As your ladder program is running and the input
condition occurs, the controller interrupts program execution and runs the PII
program file. Then, the controller resumes executing the program file from the
point where it was interrupted.
For Information About Go to Page
Using a processor input interrupt 18-1
Defining a processor input interrupt 18-5
Monitoring processor input interrupts 18-5