Specifications

6. Basic Instructions
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6-10
 Step Ladder Commands
 Symbols and functions:
Command Functions Symbol and devices
STL [Sn]
Step ladder diagram
starts
S
S
n
New Line
 Command Length: 1 Step
 Device [Sn]: S0~S127
 Begins from S0~S9
 Step S can not be repeated
RET
End of step ladder
diagram
S
RET
RET (return command
must be added at the
end of STL)
 Command length: 1 Step
 Step point S
 RET command is used at the end of the step ladder diagram that begins with S0 to
S9.
 Command Instruction
Example:
S
S10
TMR
T0 K10
SET S12
S
S12
TMR
T0 K20
SET S14
T0
T0
S
S10
Y10
S
S11
Y12
S
S12
Y12
 When step point Sn=ON, the subroutine is active, the action will delay for one scan time. Whereas Sn is
OFF, the subroutine is inactive.
 In the example, the same device (Y12) can be used in different step points. That is, when S11 or S12 step
point is activated (ON), Y12 will output. Y2 will be closed during the process that S11 transfer to S12. And
then output Y2 after S12 is ON. In this situation, no matter S11 or S12=ON, Y12 will always be ON.
 The timer can be repeatedly used in discontinuous step points. (This is a special feature of the step ladder
diagram. However, users should try to avoid repeated output relays. You should also avoid using the same
coil number that used in step ladder diagram after returning to general ladder diagram.