454
27 TROUBLESHOOTING
27.1 Checking Module Status
An example of control procedure when the TT command is used in the loopback test (station number: 00, sum check code:
Yes) is as shown below.
4. Checking loopback test result
Check for the target device side whether the data in the character area received from C24 in response to the data sent by the
target device matches the data in the character area sent by the target device. (C24 sends back to the target device the
received data, as is.)
• When the result is normal
The data in the character area that C24 sent back to the target device matches the one the target device had sent.
• When the result is abnormal
The data in the character area that C24 sent back to the target device does not match the one the target device had sent.
5. Completing loopback test
• When the result is normal
Configure the parameter settings with Engineering tool in accordance with the function to be used, and turn ON the power for
the station with C24 to start data communication.
• When the result is abnormal
Check the items below, and take corrective actions.
Item Corrective action
Reviewing the wiring of the
connection cable
Check if the connection cable is wired correctly.
MELSEC iQ-R Serial Communication Module User's Manual (Startup)
Reviewing the parameter setting of
C24
Check whether the C24 parameter settings (such as transmission setting and communication speed setting) match
that of the target device.
Page 422 PARAMETER SETTING
Check the detected error of C24 Check the error contents and take the corrective actions.
Page 440 TROUBLESHOOTING
00FF05ABCDE A 3
ABCDE 7 800FFTT 0 05
E
N
Q
H L H L H L H L
05
H
30
H
46
H
46
H
54
H
54
H
41
H
35
H
30
H
30
H
42
H
43
H
44
H
45
H
37
H
38
H
30
H
02
H
30
H
46
H
46
H
30
H
35
H
44
H
43
H
41
H
42
H
45
H
03
H
41
H
33
H
30
H
S
T
X
H L H L
H L
H L
E
T
X
TT (ACPU common command)
Head data sent
by the target device
Two characters (hexadecimal): Designate the number of characters (1 to 254) of return data to be sent immediately afterward.
Designate with a character string consisting of "0" to "9" and "A" to "F" (upper case)
(In the case of Format 1)
Command
Station No.
PC No.
Message wait
Sum check
code
Character length
Loopback data
(Data name)
The same data as
those in Character
length
Two characters (hexadecimal)
Target device
(Example)
Station No.
Character length
Loopback data
Sum check
code
Character part
(Data name)
The same data as
those in character
A part
CPU module
The
same data
(Example)
Character part
Head data to be sent by
the CPU module side
PC No.
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