Mitsubishi Electric QJ71C24N User Manual page 343

11 TROUBLESHOOTING
Error code
Error
(Hexa-
decimal)
7F68 Framing error
H
7F69 Parity error
H
7F6A Buffer full error
H
CD(DCD) signal
7F6B
H
control error
7F6C Transmission error
H
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Description
 Data does not match the stop bit
setting.
 A malfunction occurred in the network
because the power source of the
partner station was on or off.
 Noise occurs in the network.
 When the multidrop was connected,
data was transmitted simultaneously by
multiple devices.
 Data does not match the parity bit
setting.
 A malfunction occurred in the network
because the power source of the
partner station was on or off.
 Noise occurs in the network.
 When the multidrop was connected,
data was transmitted simultaneously by
multiple devices.
 OS receive buffer overflowed and
receive data was skipped.
 Data was received when CD(DCD)
signal is OFF when "CD terminal check
enabled" was designated.
 Data cannot be sent because the line is
not connected.
Signal
Corrective action
name
 Match the Q series C24 and external
device settings.
 Clear the error information according to
the ERR. clear request (YE/YF).
In addition, when communicating data
with the non procedure protocol,
SIO execute the INPUT instruction, and
read and discard the unnecessary data.
 Measure the noise.
 When connecting the multidrop, remove
the interlock so that data will not be
transmitted simultaneously by multiple
devices.
 Match the Q series C24 and external
device settings.
 Clear the error information according to
the ERR. clear request (YE/YF).
In addition, when communicating data
with the non procedure protocol,
P/S
execute the INPUT instruction, and
read and discard the unnecessary data.
 Measure the noise.
 When connecting the multidrop, remove
the interlock so that data will not be
transmitted simultaneously by multiple
devices.
 Use DTR and DC control and perform
data communications so that the buffer
does not become full. (Perform RS  CS
control when the modem function is
SIO
used.)
 If the Read Request signal was turned
ON, execute read immediately.
 Recheck the CD(DCD) signal control of
the external device.
CHn
(Send while the CD(DCD) signal is ON.)
ERR.
 Set "no CD terminal checking" and
perform communication.
 Transmit data after line connection
CHn
processing on the interface side that
ERR.
uses the modem function.
MELSEC-Q
Protocol
Non
Bidire- Pre-
MC Proce-
ctional defined
dure
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