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8. COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
(2)
Word device memory read and write
In the word device memory, each word is expressed sequentially in
hexadecimal values in 4-bit units from the higher bit.
Example:
Indication of the contents of the D350 and D351 registers
Inc
caws lnsl me conlcnl of reg slef
D350 is 56ABn 92187
n
dcc m a ,
Indicates that the content of register
D351 is 170FH (5903
in
decimal)
(1) Extension file memory read and write, buffer memory read and write,
and on-demand data when word units are specified are handled accord-
ing to the same principle as the word device memory.
(2) To output a character-string with the PR instruction externally after
transmitting it from the computer to the AlSCPU, the processing should
be as shown below:
1) The character-string to be transmitted is developed into 2-byte codes
in units of characters.
Example: To transmit "18AFH
'R"
to a sequence program.
'1"
'8'
'A'
'F'
'
H
"C
R"
Codes
.....
31 H
38H
41 H
46H
48H
ODH
'?
,
.
,,3"
'8'
"4'
','
"<
, ,
"',"
'8'
'0"
' D '
2) The character-string developed into 2-byte codes is arranged in units
of 2 characters and sent to the AlSJ71 C24.
Example: The character-string used in the above example i n 1.
"31 38 41 46 48 OD"
"3831 4641 OD48
------
u u u
"383146410D48" is sent from the computer to the AlSJ71C24
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