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13
Circuit Diagrams and Ladder Programs
Section 2-1
Electrical Circuit Display
Note
On the ZEN Support Software displays, bits in the ZEN memory
are called “relays,” program input bits are called “contacts,” and
program output bits are called “coils.”
2-1-3
Memory Areas
The following table shows the memory areas that can be used in the
ZEN ladder programs.
1st input
2nd input
3rd input
Output bit
3 inputs
1 output
Symbol
Name
Function
Usable as input
condition
Usable as
output
I
CPU Unit input
bits
Correspond to CPU Unit input
terminals.
Yes
No
X
Expansion I/O
Unit input bits
Correspond to Expansion I/O Unit
input terminals.
Yes
No
B
Button input
bits
Turn ON/OFF when operation
buttons are pressed on the CPU
Unit during ZEN operation.
Yes
No
A
Analog
comparator
bits
Compares present analog values
to setting values and outputs the
compared results for CPU Units
with DC power supply inputs.
(The analog input terminals
correspond to I4 and I5 in 10-point
CPU Units, and to Ia and Ib in 20-
point CPU Units.)
Yes
No
P
Timer/counter
comparator
bits
Compares timer/counter present
values and timer/counter present
values and settings and outputs
the compared results.
Yes
No
G
8-digit
comparator
bits
Compares 8-digit counter present
value to preset value and outputs
the compared results.
Yes
No
@
Weekly timers
Turns ON/OFF at the specified
day/time
Yes
No
Z184-E1-04.book Page 13 Thursday, November 20, 2008 4:25 PM