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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
7F23H
MC protocol
message error
• There is no data (ETX, CR-LF, etc.)
following the character area, or
designation was incorrect.
PRO
• Check and correct the external device
transmit message and restart data
communications.
7F24H Sum check error
• The sum check code calculated does
not match the sum check code
received.
• The horizontal parity code calculated
does not match the horizontal parity
code received.
• The calculated error check code does
not match the received error check
code.
P/S
• Check the sum check code of the
external device.
• Check the horizontal parity code
calculated of the external device.
• Check CRC-16 of the external device.
• If GX Configurator-SC (Pre-defined
protocol support function) was used for
protocol editing, check the sender’s
packet format to see if an incorrect
value is set for Processing method,
Code type, Data length, Data flow,
Complement calculation, or Calculating
range of the check code.
7F25H Data length error
• The length of the received data
exceeds the receive area size.
CHn
ERR.
• Correct the "data length" that is
transmitted from the external device.
• Change the "word/byte units" set by the
Q series C24 to byte units.
• Increase the receiving area of the Q
series C24.
7F26H Command error
• Another command was received before
an unlock processing while the remote
password is registered.
CHn
ERR.
• Perform the communication after the
unlock processing is normally
completed.
7F30H System error
• The OS of the Q series C24 detected
some error.
⎯ (1)
7F31H
Simultaneous
transmission error
• The Q series C24 and an external
device started transmitting
simultaneously.
⎯
• Process by agreement with the external
device.
• When necessary, change the
simultaneous transmission data
valid/invalid designation setting by GX
Configurator-SC. (address: 9B
H/13BH)
7F32H System error
• The OS of the Q series C24 detected
some error.
⎯ (1)
7F40H
• No reception watchdog timer (timer 0)
time-out occurred.
PRO
• Check if data was dropped from the
receive data.
• Check if DTR control, etc. interrupted
reception.
7F41H
• Response watchdog timer (timer 1)
time-out occurred.
⎯
• Check the status of the message
transmission destination and restart
data communications, as required.
7F42H
Time-out error
• Transmit watchdog timer (timer 2) time-
out occurred.
⎯
• Check if DTR control, etc. interrupted
transmission.
7F50H
to
7F54
H
7F60H
to
7F66
H
System error
• The OS of the Q series C24 detected
some error.
⎯ (
1)
7F67H Overrun error
• The Q series 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 in which the Q
series C24 is installed. (For the QCPU
this can be checked using special
register SD1005.) If a temporary stop has
occurred, remove its cause.
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