
B–61863E/15
3. CONFIGURATION AND OPERATION
OF STEP–SEQUENCE
PROGRAMS
STEP SEQUENCE FUNCTION
989
A step is a unit of processing in a program.
[Display]
Sn
(Pm)
[Contents]
D Define a step number (Sn), necessary for controlling execution, and
subprogram number (Pm) specifying actua processing, for a step.
D Assign a step number to a step.
D The same step number cannot be used twice in a program.
D A step has three logical states: the execution, transition to halt, and
halt states. The execution state is also called the active state. The
transition to halt and halt states are collectively called the inactive
state.
State Contents of operation Display
Sn.0
NOTE)
Activate Execution Activated step.
The action program (subprogram) is
being executed.
Sn
1
Inactivate Transition to
halt
Transition from execution to halt.
The action program (subprogram) is
executed once only, then the step
automatically transits to halt.
Sn
0
Stop Not activated state.
The action program (subprogram)
has not yet been executed.
Sn
0
NOTE
Refer to VI–4.2 PMC ADDRESS (S ADDRESS)
Example) State transition of Step B
Transition A
Inactivate (halt state)
Step B
Transition A
Transition C
Activate (execution state)
Transition C
Inactivate (transition to halt)
(Execute one time)
3.1
STEP