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10.
COMMUNICATIONS IN THE BIDIRECTIONAL MODE
MELSEC-A
(2)
Buffer memory used in the bidirectional mode
(a)
Special applications area (1 00H to
1
FFH)
Name
Wordlbyte designation area
for bidirectional mode
Bidirectional mode send buff,
memory area head address
designation area
Bidirectional mode send buff<
memory length designation
area
Bidirectional mode receive bl
er memory area head
address designation area
Bidirectional mode receive bi
er memory length designatiol
area
-
-
: r
.....
?r
-
,ff-
.....
uff-
n
-
The
(worn
oyte)
of
aata cngln
of
s message transmllltco octween
a
cornp.ter
an0 a PC CPU
is
ocs,gnateo holh a TO . n s l r ~ c l , o n
n a
sequence program.
This sets the unit of data to be stored in the send data length storage
area [default address OH) and the received data length storage area
(default address 80H)
0: Word (default)
1 : Byte
.
The head address of the area used for bidirectional mode send buffer
memory
area
(send data length storage area and send data strage
area) is designated with a TO instruction in a sequence program.
The area of the designated address is set as the send data length
storage area. (0 to FEH
or
t 2 0 H to 7FEH : Bidirectional send buffer
memory head address. (default : OH)
..........................................................
.
The length of the area used for bidirectional mode send is designated
with a TO instruction in
a
sequence program.
[default: 80H).
When OH to FFH area is used,
2H to 100H: Bidirectional send buffer memory
When 120H to DFFH
area
is used,
2H to CEOH: Bidirectional send buffer memory length
The head address of the area used for bidirectional mode receive
buffer area (receive data length storage area and receive data storage
area) is designated with
a
TO instruction in a sequence program.
-
The area of the designated address is set as the receive data length
storage area.
OH to FEH or 120H to 7FEH:Bidirectional mode receive buffer
memory head address. (default: 80H)
..........................................................
The length of the area used for bidirectional mode data receive is
designated with a TO instruction in a sequence program (default: 80H).
When OH to FFH area is used,
2H to 100H: Bidirectional receive buffer memory length
When l2OH to DFFH area is used,
2H to CEOH: Bidirectional receive buffer memory length
(continued on page 10-6)
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