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8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
8.15
Loopback Test
(1) ACPU common command
(2)
Designating the loopback test
Hem
Loopback test
lesignation Methodl
Designation in protocol 1 is shown below.
I
To set the characer length, the following condition must be met:
I
Command
Loopback test command
Character area C
I
1 r character length
5
254
I
Processing
Echoes
back
the characters to the
computer as they are received
Sym-
b o l
lesignation Example
1
ASCII
Code
54H, 54H
I
; ; ,
H l L
To execute the loopback test with the "ABCDE" at station number
" 0 " .
(Message wait time
Number o f
Points
Processed per
Communica-
t i o n
254 characters
Character area 6
2 Characters
(hexadecimal)
is 0 msec.)
AJ71C24
2
characters
(hexadecimal)
I
PC
No.
H I L
:,
State o f PC CPU
The same data
STOP
o
I
I
I
St.
NO.
H I L
Check sum is calculated
within this range
Computer
During RUN
M~~~~~~
wait time
I
PC
NO,
HIL
~
~
2
2
ON
o
E
N
0
0 5 ~
~
~
2
OFF
o
I
character
length
H
I
L
Character
length
H
I
L
o
o
lo1,
10-
(dataof
designated
character length)
Data
(same
data as
in character area C)
I
Sum
check
code
H
l
L
F
F
l C 1 ,
(6"
I
:,
T
T
5 4 ~ ,
YI
", " , ' d ", "
HIL
o
30"
o
30"
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