Mitsubishi QJ71C24N - Page 343

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MELSEC-Q
11 TROUBLESHOOTING
Protocol
Error code
(Hexa-
decimal)
Error
Description
Signal
name
Corrective action
MC
Non
Proce-
dure
Bidire-
ctional
Pre-
defined
7F68H Framing error
• 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.
SIO
• 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,
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.
7F69H Parity error
• 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.
P/S
• 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,
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.
7F6AH Buffer full error
• OS receive buffer overflowed and
receive data was skipped.
SIO
• 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
used.)
• If the Read Request signal was turned
ON, execute read immediately.
7F6BH
CD(DCD) signal
control error
• Data was received when CD(DCD)
signal is OFF when "CD terminal check
enabled" was designated.
CHn
ERR.
• Recheck the CD(DCD) signal control of
the external device.
(Send while the CD(DCD) signal is ON.)
• Set "no CD terminal checking" and
perform communication.
7F6CH Transmission error
• Data cannot be sent because the line is
not connected.
CHn
ERR.
• Transmit data after line connection
processing on the interface side that
uses the modem function.