Panasonic FP7 Series Command Reference Manual page 202

3.32 SSTP (Start Step) / NSTL (Next Step) / CSTP (Clear Step) / STPE (Step
End)
● The same process number cannot be defined for more than one process.
● The OUT instruction can be connected directly from the bus bar immediately after the SSTP
instruction.
● The SSTP instruction cannot be written in a subprogram (subroutine).
● Program code between the first SSTP instruction and STPE instruction is referred to as a
"step ladder area" and is controlled as a process. Other areas are referred to as "normal
ladder areas."
● There is a type of system relay which turns ON only for a single scan when a process with a
step ladder starts. (SR15: Step ladder initial pulse relay) This relay can be used to perform a
process only for a single scan after starting a process (e.g., resetting a counter).
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NSTL Next Step Instruction (Every Scan Execution Type)
● The NSTL R instruction starts a process specified by the relay number [R].
● The execution condition of the next step instruction becomes the start condition of the
process.
● Write the process that starts first in the next step instruction in the normal ladder area.
● The process can be started from the normal ladder area as well as a running process.
● However, when you start a process with a next step instruction from within a process, the
process that is executing and contains the next step instruction is automatically cleared and
the specified process starts.
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CSTP Clear Step Instruction
● When the CSTPn instruction is executed, the process specified by "n" is cleared. This
instruction can be used to clear the final process or to clear the processes executing in
parallel during parallel branch merge control.
● A process can be cleared from the normal ladder area or from a process that is already
started.
● When clearing multiple processes, the ZRST instruction can be used.
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STPE Step End Instruction
● This instruction indicates the end of the step ladder area. Be sure to write this instruction at
the end of the final process. The final process is defined by the SSTP and STPE instructions.
● Only one STPE instruction can be written in each main program. (It cannot be written in a
subprogram such as a subroutine or interruption program.)
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Example (1) Sequential control of processes
● This is a program that repeats the work in a certain process until it is completed, and then
moves to the next process.
● In the program, write the instruction to start the process to be executed next in each process.
When the start instruction is executed, the next process is started, and the process that had
been executing is cleared.
● Processes do not need to be executed in numerical order. You can also program the start
instruction to invoke a previous process according to conditions.
3-98 WUME-FP7CPUPGR-12