Mitsubishi MELSEC LJ71C24, User Manual

Page: 297 / 428

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15 TROUBLESHOOTING
Protocol
Error code
(Hexa-
decimal)
Error
Description
Signal
name
Corrective action
MC
Non-
proce-
dural
Bi-
direc-
tional
Pre-
defined
7F67
H
Overrun error
•
The C24 received the next data before
it completed receive processing of the
previous data. SIO
•
Decrease the data transmission rate
and restart data communications.
•
Check whether a temporary stop has
occurred in the station to which the C24
is installed. (It can be checked at special
register SD1005.) If a temporary stop has
occurred, remove its cause.
•
Perform the registration, read, and
delete to the flash ROM while the data
communication is not performed.
7F68
H
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 C24 and external device
settings.
•
Clear the error information according to
the ERR. clear request (YE/YF).
In addition, when communicating data
with the nonprocedural 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.
7F69
H
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 C24 and external device
settings.
•
Clear the error information according to
the ERR. clear request (YE/YF).
In addition, when communicating data
with the nonprocedural 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.
7F6A
H
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 Reception data read request
signal was turned ON, execute reading
immediately.
7F6B
H
CD(DCD) signal
control error
•
Data was received when CD(DCD)
signal is OFF when "CD terminal check
designation" set to "Check".
CHn
ERR.
•
Recheck the CD(DCD) signal control of
the external device.
(Send while the CD(DCD) signal is ON.)
•
Set "Not check" and perform
communication.
7F6C
H
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.