Mitsubishi MELSEC LJ71C24, User Manual

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15 TROUBLESHOOTING
15.2.3 A compatible 1C frame communications error code list
The following table lists the error code, error contents, and corrective action for errors
generated during A compatible 1C frame communications.
Protocol
Error code
(Hexa-
decimal)
Error
Error Contents
Signal
name
Corrective action
MC
Non-
proce-
dural
Bi-
direc-
tional
Pre-
defined
00
H
Disable during RUN
•
A write command was designated when
disable online change was set.
•
Parameter or sequence program was
written during RUN.
C/N
•
Change the setting to enable online
change and restart data
communications.
•
Stop the CPU and restart data
communications.
01
H
Parity error
•
The data does not match the parity bit
setting.
P/S
•
Match the C24 and external device
settings.
02
H
Sum check error
•
The sum check calculated by the C24
and the transmitted sum check are not
the same. P/S
•
Check the external device sum check.
03
H
Protocol error
•
Received message that is different from
the control procedure with the
communication protocol setting. PRO.
•
Check and correct the external device
transmit message and restart data
communications.
04
H
Framing error
•
The data does not match the stop bit
setting.
SIO
•
Match the C24 and external device
settings.
05
H
Overrun error
•
The next data was received before the
C24 received all the preceding data.
SIO
•
Decrease the transmission rate and
restart data communications.
06
H
Character area error
•
Designation method error in part of a
message.
•
A command that does not exist was
designated.
•
The number of processing points is
outside the range for the command.
•
A device that does not exist was
designated.
PRO.
07
H
Character error
•
Received data that cannot be used. PRO.
•
Check and correct the external device
transmit message and restart data
transmission.
08
H
Programmable
controller access
error
•
The CPU module cannot communicate
with the C24.
C/N
•
Replace the CPU module with a CPU
module that can communicate with the
C24.
10
H
PC No. error
•
The PC No. is not "FF", or a station No.
set in the network parameters.
C/N
•
Check and correct the external device
transmit message and restart data
communications.
11
H
Mode error
•
An error was detected upon access to
the CPU module.
⎯
•
Send again.
•
Conduct Self-loopback test and check the
C24.
12
H
Special function
module designation
error
•
A special function module does not
exist at the specified position.
C/N
•
Check and correct the external device
transmit message and restart data
communications.
21
H
Special function
module bus error
•
An error was detected upon access to a
special function module at the specified
position. C/N
•
Check the error and take corrective action
according to the manual of the
corresponding module.
42
H
Other errors
Refer to POINT .
POINT
•
If an error occurs during A compatible 1C frame communications, the C24 adds a 2-
character error code (00
H
to 10
H
, 42
H
) to the "NAK" code and returns the "NAK" code
to the external device and stores the error code (equivalent to QnA compatible
2C/3C/4C frame error code) to buffer memory address 25A
H
(CH1) or 26A
H
(CH2).
The exact error contents can be checked by reading the value stored to the
buffer memory.
Refer to Section 15.2 for a detailed description of the error codes.