DVP-ES2-EX2-SS2-SA2-SX2-Operation Manual

5. Sequential Function Chart
S10
S
Y0
S10
S
Y0
SET
S20
Y1
S20
S
Y1
Y2
S20
S
SET
Y2
S20
2. As indicated in the below diagram, make sure to connect RET instruction directly after the step
point rather than the NO or NC contact.
S20
S
S20
S
X1
X1
S0
RET
S0
RET
5.4 Points to Note for Designing a Step Ladder Program
1. The first step in the SFC is called the “initial step", S0 ~ S9. Use the initial step as the start of a
sequence and ends with RET instruction.
2. If no STL instruction is in use, step point S can be used as a general-purpose auxiliary relay..
3. When STL instruction is in use, the No. of step S cannot be repeated.
4. Types of sequences:
Single sequence: Only one simple sequence without alternative divergence, alternative
convergence, simultaneous divergence or simultaneous convergence in the program.
Complicated single sequence: Only one sequence with alternative divergence, alternative
convergence, simultaneous divergence and simultaneous convergence in the program.
Multiple sequences: More than one sequence in a program, maximum 10 sequences, S0 ~ S9.
5. Sequence jump: Multiple sequences are allowed to be written into the step ladder diagram.
• There are two sequences, S0 and S1. PLC writes in
S0 ~ S30 first and S1 ~ S43 next..
OUT
S0
OUT
S1
• Users can assign a step in the sequence to jump to
S21
S41
any step in another sequence.
• When the condition below S21 is fulfilled, the sequence
OUT
S42
will jump to step S42 in sequence S1, which is called
S30
S43
“sequence jump.”
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