Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 239)

1 Publication 1785-UM012D-EN-P - July 2005
Chapter
15
Preparing Fault Routines
Using This Chapter
Understanding the Fault
Routine Concept Fault routines execute when a PLC-5 controller encounters a major fault
during program execution.
Use a fault routine to specify how you want the controller to respond to a
major fault. If your controller experiences a fault during program execution,
you can tell the controller to interrupt the current program, run your fault
routine, and then continue processing the original program.
A fault routine processes the major fault bit found in S:11 and determines the
course of program execution based on the fault bit present. Fault routines
provide a means to either:
• systematically shut down a process or control operation
• log and clear the fault and continue normal operation
For a detailed list of the words in the controller status file, see
Appendix B.
Responses to a Major Fault
When the controller detects a major fault, the controller immediately
interrupts the current program. If a fault routine exists (i.e., program file is
specified in S:29 as a fault routine), the controller runs that fault routine
program for recoverable faults. Depending on the type of fault, the controller
then:
For Information About See Page
Understanding the fault routine concept 15-1
Understanding controller-detected major faults 15-2
Defining a fault routine 15-4
Defining a watchdog timer 15-5
Programming a fault routine 15-6
Monitoring faults 15-11