Delta DVP-ES2/EX2/SS2/SA2/SX2/SE 5.1 Step Ladder Instruction [STL], [RET] , 5.2 Sequential Function Chart (SFC)

DVP-ES2EX2/SS2/SA2/SX2/SE Operation Manual - Programming
5.1 Step Ladder Instruction [STL], [RET]
Mnemonic Operands Function Program steps
STL S0~S1023 Starts STL program 1
Controllers
ES2/EX2 SS2 SA2 SX2
Explanation:
STL Sn constructs a step point. When STL instruction appears in the program, the main program will
enter a step ladder status controlled by steps. The initial STL program has to start from S0 ~ S9 as
initial step points. The No. of Step points cannot be repeated.
Mnemonic Operands Function Program steps
RET None Ends STL program 1
Controllers
ES2/EX2 SS2 SA2 SX2
Explanation:
RET instruction indicates the end of a step ladder program starting from S0 ~ S9, i.e. the execution
returns to main program after RET is executed. Maximum 10 initial steps (S0 ~ S9) can be applied
and every initial step requires a RET instruction as an end of STL program. With the step ladder
program composed of STL/RET instructions, SFC can perform a step by step control process.
Program Example:
Step ladder diagram:
M1002
ZRST S0 S127
SET S0
SET S20
Y0
SET S30
Y1
SET S40
Y2
S0
RET
END
X0S0
S
S20
S
X1
S30
S
X2
S40
S
X3
SFC:
S0
S20
S30
S40
S0
M1002
X0
X1
X2
X3
Y0
Y1
Y2
5.2 Sequential Function Chart (SFC)
In the application of automation control, a seamless combination between electrical control and
mechanical control is required for completing an automation process. The sequential control of
automation process can be divided into several steps (states). Each step is designated with own
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