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8. COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
(1) To designate the bit device ranges in units of words, the bit device
number must b e a multiple of 16.
For special relays M, whose device number is M9000 or greater,
designation is possible by using "9000
+
multiples of
16".
(2) Although the ranges are designated for M, L, and
S,
if the range for M
is designated by L o r
S,
the same processing occurs. This is also true
for the ranges for L and S.
(3) The ranges of special relays (M9000 t o M9255) and special registers
(D9000 to D9255) are divided into the areas for read only, write only,
and system use.
Trying to write data to the ranges outside the write-only area might
cause the PC CPU to malfunction.
The ACPU programming manual gives details concerning special
relays and special registers.
(4)
When using the dedicated instructions for the A2ACPU(Sl) and
A3ACPU extension file registers, use the commands explained in Sec-
tion
8.8
for read and write operations for the file register (R).
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