4 Step Ladder Instructions
DVP-PLC Application Manual
4-3
4.3 How does a Step Ladder Instruction Work?
STL instruction is used for designing the syntax of a sequential function chart (SFC), making the program
designing similar to drawing a flow chart and allowing a more explicit and readable program. From the figure in the left
hand side below, we can see very clearly the sequence to be designed, and we can convert the sequence into the
step ladder diagram in the right hand side.
RET instruction has to be written at the end of every step sequence, representing the end of a sequence. There
can be more than one step sequence in a program. Therefore, we have to write in RET at the end of every step
sequence. There is no limitation on the times of using RET which is used together with S0 ~ S9.
If there is no RET instruction at the end of a step sequence, errors will be detected by WPL editor.
S0
S21
S22
S23
M1002
S0
SET
SET
S22
S0
RET
S21
S
S22
S
SET
S21
S0
S
S23
S
SET
S23
M1002
initial pulse
1. Actions of Step Ladder:
A step ladder is composed of many steps and every step controls an action in the sequence. The step ladder
has to:
a) Drive the output coil
b) Designate the transition condition
c) Designate which step will take over the control from the current step
Example:
SET
Y1
Y0
SET
S20
Y10
SET
S30
S10
S
X0
S20
S
X1
SET
Y1
Y0
SET
S20
Y10
SET
S30
S10
S
X0
S20
S
X1
When X0=On,
S20 = On,
S10 = Off.
Explanation:
When S10 = On, Y0 and Y1 will be On. When X0 = On, S20 will be On and Y10 will be On. When S10 = Off, Y0
will be Off and Y1 will be On.
2. Timing Diagram of Step Ladder:
Содержание DVP-PLC
Страница 1: ...PLC PLC...
Страница 28: ...1 Basic Principles of PLC Ladder Diagram DVP PLC Application Manual 1 24 MEMO...
Страница 192: ...4 Step Ladder Instructions DVP PLC Application Manual 4 22 MEMO...
Страница 250: ...6 Application Instructions API 00 49 DVP PLC Application Manual 6 38 X0 DIV D0 D10 D20 D0 D10 K4Y0 DIV...
Страница 270: ...6 Application Instructions API 00 49 DVP PLC Application Manual 6 58 RST M0 X0 RST T0 RST Y0 FMOV K0 D10 K5...
Страница 337: ...7 Application Instructions API 50 99 DVP PLC APPLICATION MANUAL 7 53 X10 STMR T10 K50 Y0 Y3 X10 Y1 Y2 5 sec 5 sec...
Страница 458: ...8 Application Instructions API 100 149 DVP PLC Application Manual 8 56 or relay itself See 2 3 for more information...
Страница 472: ...8 Application Instructions API 100 149 DVP PLC Application Manual 8 70 MEMO...
Страница 574: ...9 Application Instructions API 150 199 DVP PLC Application Manual 9 102 MEMO...