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8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
This chapter explains the details and methods of specifying control
protocols
1 to
4
along with examples.
8.1
Data Flow in Communications with Dedicated Protocols
(1)
The computer reads data from the PC CPU
r m n
.&tension
file
information
*Sequence program
Microcomputer program
i - - - - - _ l
* c o m m e n t
I
I
I
I
1
~ a r a m e t e r
(2) Commend
(7)
Various
data
(10) Response
~~
~
I
PC CPU information
(2) The computer sends
data to the
PC CPU
(3) Read request
PC CPU
I
r - - I - -
,
Device
memory.
1
etc.
I
L - - - - - _ l
I
0s
Sequence
I
p,ograrn
I I ?
I
161
Various data
-
- - - - -
-
I
\
\
Special function module
\
(2) Commands, data, etc.
0
Device memory information
0
Extension file register infor-
mation
Sequence program
Microcomputer program
Comment
Parameter
* P C CPU information
(3)
The PC CPU sends data to the computer
PC CPU
AJ71C24
I
(2)
Send request
( - j T t
(I] Send
request
+
Data write request
I
I
Device memory.
etc.
Special function module
(5)
Data
On-demand data
computer
y
)
Re4"erf
Dalacom-
municafionr
program
0
Data cam-
municationr
program
0
The OS (operating system) shown in the above illustrations is the software that
uses resources
such
as
the PC CPU, memory, terminals, files, and network efficiently.
In this manual, this software is described as the system program or system
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