Chapter 4 Sfc Program Configuration - Mitsubishi Electric MELSEC-Q Series Programming Manual

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SFC PROGRAM CONFIGURATION
This chapter describes the SFC program symbols, SFC control instructions and SFC information devices that comprise an
SFC program.
When applying the program examples introduced in this manual to an actual system, ensure the applicability and confirm that
it will not cause system control problems.
As shown below, an SFC program consists of an initial step, transition conditions, intermediate steps, and an END step. The
data beginning from the initial step and ending at the END step is referred to as a block.
An SFC program starts at an initial step, executes a step following a transition condition in due order every time that transition
condition is satisfied, and ends a series of operations at an end step.
• When the SFC program is started, the initial step is executed first. While the initial step is being executed, whether the
transition condition following the initial step (transition condition 0 (t0) in the figure) has been satisfied or not is checked.
• Only the initial step is executed until transition condition 0 (t0) is satisfied. When transition condition 0 (t0) is satisfied, the
execution of the initial step is stopped, and the step following the initial step (step 1 (S1) in the figure) is executed. While
step 1 (S1) is being executed, whether the transition condition following step 1 (transition condition 1 (t1) in the figure) has
been satisfied or not is checked.
• When transition condition 1 (t1) is satisfied, the execution of step 1 (S1) is stopped, and the next step (step 2 (S2) in the
figure) is executed.
• Every time the transition condition is satisfied in order, the next step is executed, and the block ends when the end step is
executed.
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