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How to Use the Step Ladder Program Block Appendix A
When multiple steps are used as a step sequence
Step Ladder Program blocks can be broken up into 99 steps STEP01 to 99. Whereas STEP00 operates at all
times when the operating conditions are satisfied, one of steps STEP01 to STEP99 operates when the operat-
ing conditions are satisfied
• A Step Ladder Program comprising STEP01 to STEP99 is called a “step sequence.” Sequence control
instructions (refer to List of Sequence Control Instructions in this Appendix) such as JUMP (jump to a
specified step) can be used in step sequences.
• Movement between steps STEP01 to STEP99 is performed according to the following conditions:
1. Move to next STEP when the input conditions of the final sequence command in the STEP are satisfied. ∗1
2. Jump to a specified step according to the JUMP command.
3. Move to the next STEP (STEP+1) when the time set by the STEP TIMER command has elapsed.
Movement between steps when input conditions are satisfied in this way allows step progression control to be
performed.
∗1: Basically, movement between STEPs is movement to the next STEP when the input conditions of the last
sequence command are ON.
Example
• To break up a Step Ladder Program, use the STEP command (21). (The default step for the Step Ladder
Program block is the constant operation step STEP00.)
• When run/stop command S1 (ITEM008) of the Step Ladder Program block turns ON, STEP00 (constantly
available step) and STEP01 (first step of step sequence) operate. Program execution is made to move to
other steps (also to specified STEPs in other Step Ladder Program blocks) when the input conditions are
satisfied during STEP01.
STEP01 onwards only can also be described without describing STEP00 (constantly available step).
Single step (normal)
STEP00
ITEM
Command Operand
011 (LOAD)
012 (AND)
013 (OUT)
014 (LOAD NOT)
Max. 410
STEP 01
STEP 02
Move to STEP02 when this input condition
turns ON.
Accordingly, the result is as if the STEP
move instruction exists virtually here.
STEP move
instruction
To next STEP
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