Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 175)

Chapter
15
15Ć1
Selectable Timed Interrupt
This chapter describes a method to execute subroutines at timed intervals. This
method is called selectable timed interrupt.
Selectable timed interrupt is a special subroutine that can be programmed into
the subroutine area and designated as a Selectable Timed Interrupt (STI). This
subroutine can then be executed at timed intervals.
General programming facts are:
First instruction is the first rung of the subroutine area must be a Get
instruction. This identifies it as an STI.
Get instruction must be used solely for the purpose of designating the time
period of the STI.
STI subroutine execution time should not exceed approximately 2/3
STI interval.
Keystrokes: To program a selectable timed interrupt subroutine, a Get
instruction must be the first instruction in the first rung after the use program
subroutine area statement (Figure 15.1). This designates that an STI follows.
Then, you can program your subroutine. The transition time from main
program to STI and return is 100
µ
s.
Chapter Objectives
Introduction