Basic Instructions
2 − 80
When you need to clear an entire processes in step ladder program, use the master control (MC and MCE)
instructions as shown below.
Example: All processes are cleared when X0 becomes on.
X0
SSTP 1
SSTP 2
SSTP 3
MC 0
STPE
MCE 0
ED
Step
ladder
area
Master control
instructions
It is not necessary to execute processes in order of process numbers. You can execute two or more
processes at the same time.
Once you force on or off an output that is programmed in a process not yet executed, the output condition is
maintained until the process starts even if the forced on and off operation is canceled.
Step ladder operations
When the step ladder processes are programmed, program execution proceeds in the ordinary ladder area
and in the processes triggered by the next step instructions (NSTL or NSTP). Processes that have not been
triggered are ignored.
SSTP 1
SSTP 2
SSTP 9
STPE
ED
Not executing process 1
Executing process 2
Ordinary ladder area
Executing
Not executing
Not executing process 9
Ordinary ladder area
Executing
Not executing
Executing
In the diagram, program execution occurs in the ordinary ladder areas and in process 2.
The moment the step ladder process is opened, step ladder internal pulse relay R9015 turns on for an instant
only in the first scan of the process. You can use R9015 to reset a counter or shift register used in the opened
process.
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