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8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
8.4.1
Control format 1
St. No. : Station number
Description
ro
read data
from the PC
CPU to the
ComDuter
To write data
from the
computer to
the PC CPU
Remarks
C o n t r o l Protocol
Transmission sequence
- .
P
or
A J i l C 2 4
-
Transmission sequence
Computer
N O .
code
H L
H L H
L
computer
-
(1)The sum check is enabled by DIP switch 21.
The sum check code only exists when the sum check is enabled by turning DIP swit'
(2)The sum check is made for characters marked
""'
in these diagrams.
(3) In these diagrams, the contents of "character area A", "character area
B", and "chaii
depend on the individual system.
For details, see the relevant sections. The c c
character areas are the same for all 4 formats.
H , L ,
,
:
,
,
,
H , L
ch 21 ON.
acter area C"
intents
of all
A
S t
No.
H .
L
AJ71C24
:,
Sf.
NO.
H L
E
C1
Message
waitlime
Com-
mand
H . L
S t
NO.
H , L
PC
No.
H L
S t
No.
H
L
Character
area c
Cam-
mend
n
L
Merrage
waittime
PC
No.
H
L
PC
NO.
H , L
2zk
code
Character
areaA
Character
area 8
: : $
code
H , L
;
z", " , "
H , L
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