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I/O Allocation
Section 4-2
Expansion I/O Board I/O
Allocation
• Up to three Expansion I/O Boards can be connected to a CPU Board.
• Expansion Boards with 32 I/O points are allocated one input word and
one output word, and models with 40 or 64 I/O points are allocated two
input words and two output words.
• Input and output words are allocated in the order that the Boards are con-
nected to the CPU Board, starting from the top terminal block.
m: The last input word allocated to the CPU Board or to the previous Expan-
sion Board if one is already connected.
n: The last output word allocated to the CPU Board or to the previous Expan-
sion Board if one is already connected.
32-point Expansion I/O Boards
40-point Expansion I/O Boards
16 inputs
Word m+1, bits 00 to 15 in IR
16 outputs
Word n+1, bits 00 to 15 in IR
Inputs
Outputs
m+1
n+1
15
14
13
12
11
10
09
08
07
06
05
04
03
02
01
00
Bits
24 inputs
Word m+1, bits 00 to 07 and
word m+2, bits 00 to 15 in IR
16 outputs
Word n+1, bits 00 to 07 and
word n+2, bits 00 to 07 in IR
Inputs
m+1
m+2
15
14
13
12
11
10
09
08
07
06
05
04
03
02
01
00
Outputs
n+1
n+2
Bits
Do not use
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