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8. COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
8.4.3
Control format 3
St. No. : Station number
Description
-o read data
rom the PC
:PU to the
:omputer
T o
write data
rom the
x m p u t e r to
he PC CPU
Remarks
Control Protocol
Transmission sequence
l i l
2;.
1
-
*
w
or
(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 swi
(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 "chas
depend
on
the individual system.
For details, see the relevant sections. The
c
character
areas are
the same for all
4
formats.
-
q q
I ,
k
q q
1 . L
tch 21 ON.
racter area C"
ontents of all
or
;
S
;
AJ71C24
:
s
AJ7lC24
___,
St.
E
X
Transmission sequence
H
L H . L
PC
NO
H
L
E,
H L
zzk
H , L
PC
NO,
H
L
st
No.
H
L
St.
NO.
H , L
Com-
ma, ,
H . L
corn-
mand
H
L
PC
NO.
H . L
M e s s a ~ e harmer
waittime
areaA
Mesrage
,,;,time
Character
are..
Character
a e a c
:
,
;
:z;
H , L
,"h"zk
< ,
,
H , L
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