Delta DVP-ES2/EX2/SS2/SA2/SX2/SE Step Ladder Instruction STL, RET, Sequential Function Chart SFC

DVP - ES2EX2/SS2/SA2/SX2/SE Operation Manual - Programming

5.1Step 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:									SFC:
	M1002
						ZRST	S0	S127	M1002
						SET	S0			S0
									X0
		S0		X0
			S			SET	S20
										S20	Y0
	S20
			S			Y0			X1
					X1
	S30					SET	S30			S30	Y1
									X2
			S			Y1
					X2		S40			S40	Y2
	S40					SET			X3
			S			Y2
					X3
						S0				S0
						RET
						END

5.2Sequential 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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