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There are two methods for allocation.
Allocate each device by channel
Allocate so that the total number
of allocated words is minimized
(two devices may be allocated to
one word)
Examples of allocation are as follows:
Allocation when outputs or inputs are as shown below
#00
#01
#02
#03
#04
#05
Allocation by Word
+0 word
+1 word
+2 word
+3 word
+4 word
+5 word
+6 word
Allocation Minimizing the Number of Allocated Words
+0 word
+1 word
+2 word
+3 word
+4 word
294
Each slave is always allocated the low byte (lower 7 bits)
of the word. Therefore, each slave is allocated one word
even if 1-byte I/O slaves come sequentially.
Example:
High
Low
15
...
8
7
...
#0
#1
#3
#4
#6
If there are 1-byte I/O slaves, allocation is in the order of
low byte (lower 7 bits) to high byte (upper 7 bits) to create
as few unused areas as possible.
Example:
High
Low
15
...
8
7
...
#0
#3
#1
#4
#6
1 byte
2 bytes
1 byte
4 bytes
1 byte
1 byte
High
15
High
15
#05
0
Node address order
Unused
0
Node address
order
Unused
8 7
#01
#03
#03
8 7
#01
#03
Appendix A
Low
0
#00
#02
#04
#05
Low
0
#00
#02
#04
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