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I/O Allocations Section 8-1
8-1 I/O Allocations
With a CJ-series PLC, the CPU Unit can automatically allocate I/O words to
the Basic I/O Units that are started and start operation automatically when the
power supply is turned ON. Words will be allocated to Special I/O Units and
CPU Bus Units according to the unit numbers set on the Units.
To help prevent troubles from occurring when adding Units or when the wrong
Unit is mounted, I/O tables can also be registered in the CPU Unit. (Refer to
8-
2 Creating I/O Tables
for details.)
8-1-1 Unit Types
Memory is allocated differently to Basic I/O Units, Special I/O Units, and CJ-
series CPU Bus Units.
O
D
2
1
1
Note: The first word on each Rack can be set from the CX-
Programmer to an address between CIO 0000 and
CIO 0999 to change the default setting
(consecutively from CIO 0000).
Allocations
CIO 0000 to CIO0079
Words are allocated as required
by each Unit in sequence to
Units in the order they are
connected.
I/O Area
Basic I/O Units
2
ON
4
TERM
RD2
SD2
RDY
NO.
UNIT
ERH
OFF
WIRE
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
ERC
RUN
SCU41
RD1
TER1
SD1
PORT1
(RS422
/485)
PORT2
Allocations
Special I/O Unit Area
CIO 2000 to CIO 2959
Words are allocated ten at a
time to each Unit according to
unit number.
Note: The maximum total number of Units
that can be connected is 40, which means the
maximum number of Special I/O Units is 40.
Allocations
CPU Bus Unit Area
CIO 1500 to CIO 1899
Words are allocated 25 at a time
to each Unit according to unit
number.
Special I/O Units
CPU Bus Units
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