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4. COMMUNICATIONS USING A DEDICATED
PROTOCOL
MELSEC
QnA
Trainer operation
Write the sequence program shown in item to the
PC CPU and the BASIC program
shown in item
to the external device.
After writing, set the PC CPU and external device to RUN.
If there are no errors, send and receive data using the following procedure.
@
The external device CRT screen continuously displays 1 to 100 numeric characters.
(On-demand function interrupt wait state)
Main program running
When the on-demand function is executed,
the interrupt program.
1 2 3 4 5
............
..........................
..........................
..........................
(Continuous numeric characters)
..............
99 100
External device screen
@
@
When X0 is turned ON, the sequence program sends an on-demand command to the
QC24 and sends the data "1 2345678H" to the external device.
The external device executes the interrupt processing routine and displays the receive
data.
Device
W
D~~~~~
0
1 2 3 4 5 6 7 8 9 A B
C
D E F
Hexadeclma'
D
0.
D
l
0001
D
2
0000
D
3
0002
0000
D
4
m B m
m m
0000
D
6
1234
D
9
0000
D
7
D
8
0000
oooo
D
10
0000
Dsplay
'
16B1t
D
5
5678
mm
mmmm
GPPQ batch monitor screen
Data received from AJ71 QC24
Receive data ASCII code (hexadecimal)
02
t
STX
30
}
00
30
46
}
FE
45
"1 2345678"
36
37
38
03
t
E 3 X
Hit any key to return to main program
External device screen 2
If you have any situations as follows, please read the explanations
\
CRT does not switch from external display screen
@
Was sequence program
a
written to the PC CPU?
to external display screen
@
even though X0 is turned
Are the cables connected (Section 3.3) correctly?
ON
Data set in the PC CPU and the data received by the
Are the external device settings (Section 3.4) and
(external
device
are
different
QC24 switch
settings
(Section
4.2)
correct?
4
-
41
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