Mitsubishi Electric MELSEC-Q00U(J)CPU User Manual page 240

(6) Error codes during communication with the serial communication function
The following table lists the error codes (together with their descriptions and corrective actions) sent from the
CPU module to the external device when an error occurs during communication using the serial communication
function.
Error code
Error item
(hexadecimal)
4000
H
to
-
4FFF
H
Unregistered
7155
H
monitor error
Request target
7157
specification
H
error
Request data
7164
H
error
Disabled during
7167
H
RUN
7E40
Command error
H
7E41
Data length error
H
7E42
Data count error
H
7E43
Device error
H
Continuous
7E47
H
request error
Receive header
7F21
H
section error
7F22
Command error
H
MC protocol
7F23
H
message error
7F24
Sumcheck error
H
238
Description
Error detected by the CPU module
(error occurred by other than the serial
communication function)
A monitor request was given before monitor
registration.
A CPU module that does not support the
serial communication function is specified
as a request target module or is in the
specified route.
The requested data or device specification
method is incorrect.
A write command was specified while
online change is disabled.
A subcommand or a command that does
not exist is specified.
The number of points specified for random
write/read exceeds the number of points
enabled for communication.
The requested number of points exceeds
the range of the command.
The device specified does not exist.
The device specified cannot be specified by
the corresponding command.
The next request was received before the
response message was returned.
The command (frame) section specified is
in error.
The ASCII code received cannot be
converted into binary.
The command or device specified does not
exist.
The data (such as ETX, CR+LF) specified
after the character part does not exist or in
error.
The calculated sumcheck does not match
the received sumcheck.
Corrective action
Refer to the following manual and take corrective
action.
QCPU User's Manual (Hardware Design,
Maintenance and Inspection)
Give a monitor request after registering a device to be
monitored.
Check that the transmission message is addressed to
the CPU module that supports the serial
communication function. If not, correct the address
and restart communication.
Check the sent message/requested data of the
external device, correct it, and restart communication.
• Enable the online change and restart
communication.
• Set the CPU module to STOP and restart
communication.
Check and correct the sent message of the external
device and restart communication.
Check and correct the sent message of the external
device and restart communication.
Check and correct the sent message of the external
device and restart communication.
Check and correct the sent message of the external
device and restart communication.
Do not give continuous requests from the external
device.
Match the monitoring time of timer 1 with the time-out
time of the external device.
Check and correct the sent message of the external
device and restart communication.
Check and correct the sent message of the external
device and restart communication.
Check and correct the sent message of the external
device and restart communication.
Review the sumcheck of external device.