How to Use the Step Ladder Program Block
Appendix 1
209
: Can be used
: Cannot be used
Command
Command
code
Ladder symbol
Operand
Description
Input
conditions In logic
sequence
In step
sequence
Draw line
Connects vertical or
horizontal lines.
Delete line
Deletes vertical or
horizontal lines.
END
00
ED
Indicates the end of a
program.
Note: The END
instruction is
automatically
placed at the end
of program when
the Step Ladder
Program block is
prepared using
CX-Process Tool.
It is placed after
STEP00 when the
program comprises
STEP00 only, and
is placed after the
nth STEP where
the program ends.
Not required
NO
OPERATION
30
NP
This instruction has no
function. (No processing
is performed for NOP.)
Not required
Note 1
The ON signal for one operation cycle that is generated by the differentiate up (DIFU) or
differentiate down (DIFD) command automatically turns OFF at the start of the Step Ladder
Program block of the next operation cycle. (This signal does not turn OFF by the DIFU or DIFD
command in the Step Ladder Program.)
Note 2
When the ON signal for one operation cycle that is generated by the DIFU or DIFD command
is used by another function block, set the operation cycle to the same or higher than the
operation cycle of the Step Ladder Program. The ON signal sometimes cannot be read
normally when an operation cycle that is lower than the operation cycle of the Step Ladder
Program is set.
A contact ITEM that has been turned ON by the OUT command stays ON even if program
execution moves to the next STEP. For this reason, to perform step progression control in a
step sequence, use the RESET command at the next STEP to turn OFF the contact ITEM that
has been turned ON.