Mitsubishi Electric L02SCPU User's Manual And Reference page 235

(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 to 4FFF

H H
Unregistered
7155
H
monitor error
Request target
7157
H
specification 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
Sum check error
H
7F67
Overrun error
H
7F68
Framing error
H
7F69
Parity error
H
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
wrong.
A write command was specified while online change is
disabled.
A command or a subcommand 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 and CR + LF) specified after the
character part does not exist or in error.
The calculated sum check does not match the received
sum check.
The next data was received before the CPU module
completed receive processing.
• The stop bit setting does not match.
• Communication line became unstable by powering
on/off the target device.
• Noise is generated on the communication line.
• The parity bit setting does not match.
• Communication line became unstable by powering
on/off the target device.
• Noise is generated on the communication line.
CHAPTER 3 CPU MODULE FUNCTIONS
Corrective action
Refer to the following manual and take corrective
actions.
MELSEC-L CPU Module 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 sum check of the external device.
Reduce the communication speed and restart
communication. Check the CUP module for a momentary
power failure. (For the CPU module, use the special
register SD53 to check.) When a momentary power
failure occurs, remove its cause.
• Match the setting of the CPU module with that of the
external device.
• Take noise reduction measures.
• Match the setting of the CPU module with that of the
external device.
• Take noise reduction measures.
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