Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 243)

Chapter 13
Using Application Specific Instructions
13–17
These instructions are generally used in pairs. The purpose is to create zones
in which STI interrupts cannot occur.
Using STD
When true, this instruction resets the STI enable bit and prevents the STI
subroutine from executing. When the rung goes false, the STI enable bit
remains reset until a true STS or STE instruction is executed. The STI timer
continues to operate while the enable bit is reset.
Entering the Instruction
You enter the instruction from within the program monitor functional area.
P 0 0 7 S T D
Using STE
This instruction sets the STI enable bit and allows execution of the STI
subroutine. When the rung goes false, the STI enable bit remains set until a
true STD instruction is executed. This instruction has no effect on the
operation of the STI timer or setpoint. When the enable bit is set, the first
execution of the STI subroutine can occur at any point up to the full STI
interval.
Entering the Instruction
You enter the instruction from within the program monitor functional area.
P 0 0 7 S T E
STD/STE Zone Example
In the program that follows, the STI function is in effect. The STD and STE
instructions in rungs 6 and 12 are included in the program to avoid having
STI subroutine execution at any point in rungs 7 through 11.
The STD instruction (rung 6) resets the STI enable bit and the STE
instruction (rung 12) sets the enable bit again. The STI timer increments and
may time out in the STD zone, setting the pending bit S2/0 and lost bit
S5/10.
Selectable Timed Disable
(STD) and Enable (STE)
STD
SELECTABLE TIMED DISABLE
STE
SELECTABLE TIMED ENABLE
False
6.69
True
3.16 STD
10.13 3.16 STE
Execution Times (
µ
sec) when:
Ladder representation:
5
ENT
5 1
FUN
To enter the function code, press:
6
ENT
5 1
FUN
To enter the function code, press: