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8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
The device numbers that can be designated vary according to the type of
memory cassette and the PC CPU parameter setting.
(The UTLP-FNl
Operating Manual or the A2A(Sl)/A3A CPU User's Manual give details.)
For block numbers that do not exist in the memory cassette, device numbers
are not allocated. I n this case, the device numbers are allocated as indicated
below, skipping non-existent block numbers.
Device
numbers
0
m
to
I
Block No.
1
area
I
to
I
Block No. 2area
I
1 6 3 8 3 1
I
-
Blocks Nos. 3 to 9 do not exist
,6384
1
due to low memory capacity.
(b) A device number is designated i n
7
characters.
Designation example 1
:
To designate R10 in block number 1:
000001 0
A blank code (2OH) can be
used to express leading zeros
Designation example 2:
(the underlined os in 0 ~ 8 2 0 0 ) .
To designate R8 in block number 2:
0008200
POINTS
(1) The AnACPU dedicated commands NR and NW can only be used for
readlwrite operations at the extension file registers of block numbers 1
to 256.
I
They can be used regardless of the parameter's file register setting.
(2) Use the commands described in Section 8.1 5.1 to access the parameter
set file registers (R) or to access a file register by designating a block
number.
(3)
The following equation is used to calculate the head device number to
be designated with the AnACPU dedicated commands NR and NW. (To
designate device number "m" (0 to 8191) in the "n"th block (n
t
1))
I
Head device number
=
(n-1) x 8192
+
m
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