Rockwell Automation 9323-PA1E USER MANUAL APS 6.0 - Manual (Page 291)

Preface
Advanced Programming Software User Manual
15–10
Single Step Test
This mode is used with SLC 5/02, SLC 5/03, and SLC 5/04 processors. To use the
Single Step Test mode with an SLC 5/02 processor, you must first save and compile
your program offline with the Single Step option enabled. Refer to chapter 9 for
saving files. Note that your program size and scan time increases when you use an
SLC 5/02 processor. Refer to the Instruction Set Reference Manual for more
information on estimating your scan time.
The Single Step Test mode is always available when using an SLC 5/03 or SLC 5/04
processor. Use the single step test mode to test a single rung or a group of rungs.
When you enter this mode, “SRG” appears on the status line.
When in the Single Step Test mode, the power rail character B replaces an edit zone
marker when execution reaches the break point or end rung while testing a group of
rungs. The edit zone marker is redrawn once the rung is executed. For rungs with
an I and R edit zone pair, the currently active rung will have its edit zone marker
replaced with the Single Step Test rail character.
Note The following four characteristics are associated with the Single Step Test mode
(SRG) when using SLC 5/03 and SLC 5/04 processors:
•
You must modify your program to step through a fault routine. We recommend
adding a test rung containing the Jump to Subroutine (JSR) instruction to the
fault routine. Once you have done this, you will be able to step through the fault
routine.
•
The Selectable Timed Interrupt (STI) may appear to run 18% slower than
background timers. This will cause the program timing to be skewed between
the STI and other timers in your program.
•
When stepping through user interrupts, the user watchdog timer is replaced by
an internal software timer that will expire within approximately five seconds.
•
A STI, DII, or I/O Event Interrupt cannot occur during an I/O scan or while
servicing a communication packet. Interrupt subroutine execution will only
occur between rungs while your program is being executed.