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MELSEC-Q
10 TROUBLESHOOTING
10.3.14 Troubleshooting when data cannot be communicated via modem
Symptom Cause Corrective action MC
Non
procedure
protocol
Bidirection
al protocol
•  A modem initialization error occurs.
•  Check the error code and execute
processing accordingly.
•  Modem connection channel designation is
not performed.
•  Set Modem connection channel
designation.
•  Auto modem initialization
cannot be executed.
•  There is an error in the switch settings in the
GX Developer.
•  Review the switch settings. Set it to match
the local station modem and the TA.
•  Communication protocol setting is incorrect.
•  Set the communication protocol to MC
protocol, format 5.
•  Transmission setting does not match the
external device.
•  Review the transmission setting.
•  Data cannot be
communicated with GX
Developer supporting the Q
series C24.
•  Communication rate does not match the
external device.
•  Review the communication rate setting.
•  The product is not supported by the GX
Developer.
•  Confirm the GX Developer’s S/W version.
•  There was an error in the GX Developer
connection system.
•  Check the GX Developer’s connection
system.
•  Set the connection system on “callback
reception waiting” and connect.
•  The GX Developer does not
receive the callback signals
from the Q Series C24.
•  There is an error in the GX Developer side’s
modem settings.
•  Set the modem’s settings on "Auto
Reception."
• There s an error in the GX Developer’s
connection system.
•  Check the GX Developer’s connection
system.
•  Correct the Q Series C24’s settings.
•  Callback connections from
the GX Developer are
refused by the Q Series
C24.
•  There is an error in the connection system’s
telephone No.
•  Check the telephone No.
•  Change the telephone No. to the data for
callback.
•  There is an error in the Q Series C24
setting value.
•  Set the callback function designation on the
setting 1 to 3.
•  There is an error in the GX Developer’s
connection system.
•  Check the GX Developer’s connection
system.
•  Check the Q Series C24’s settings.
•  When performing Auto
(callback: during fixed/
during designated number)
from the GX Developer,
connection to the Q Series
C24 is refused.
•  There is an error in the telephone No. of the
connection system.
•  Check the telephone No.
•  Change the telephone No. to the data for
callback.
•  The timer value for the status of the modem
used or the line is short.
•  Adjust each of the timer values for the
callback function on the GX Developer side.
(Line callback cancel wait time, callback
delay time)
•  It is possible to connect
from the GX Developer, but
callback from the Q Series
C24 cannot be performed.
•  There is a problem with the modem
specifications or settings.
•  Check the modem’s specifications and
settings.