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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
7E70H CPU error
• The communication with the CPU could
not be performed normally.
C/N
• If there is an error in the CPU, eliminate
the error on the CPU side and
communicate again.
7E73H
to
7E8E
H
7EC1H
7EC2H
System error
• The OS of the Q series C24 detected
some error.
⎯ (
1)
7EC3H
Double send
request error
• A send request was performed while
another send request was being
processed.
⎯
• Interlock (handshake) the send
requests.
7EC4H
Transmission data
count error
Transmission/
receipt buffer setting
error
• Data larger than the transmit buffer size
was transmitted.
• Transmission/receipt buffer settings out
of range.
⎯
• Make the transmission data count
smaller than the transmit buffer size.
• Make the non procedure protocol
transmit buffer size larger.
• Designate the first address and size of
transmission/receipt buffer in the free
area range of the user.
7EC5H
Flash ROM access
error
• Write to Flash ROM was requested
when the setting modification
enable/disable switch in the GX
Developer was set to OFF.
⎯
• When writing to Flash ROM, set switch
shown left of the given interface to ON
and restart the Q series C24.
7EC6H
Flash ROM access
error
• There is an error in the Flash ROM
read/write request contents.
⎯
• Check the read/write request data and
designate the correct data.
7F00H System error
• The OS of the Q series C24 detected
some error.
⎯ (1)
• The next data was received before
processing of the previous data was
completed.
• Increase the transmission time by
performing handshake with the external
device, etc.
7F01H Buffer full error
• Multiple requests was simultaneously
issued for one channel.
⎯
• Perform handshake with the request
source external device.
7F02H
to
7F06
H
System error
• The OS of the Q series C24 detected
some error.
⎯ (
1)
• An ASCII code that cannot be
converted to binary code was received.
• Check and correct the external device
transmit message and restart data
communications.
• An odd number of bytes of data was
received during data communications
using ASCII
BIN conversion.
• When data are converted between
ASCII and binary, always transmit data
in units of even bytes.
7F20 H
ASCII
BIN
conversion error
• When data are received by the protocol
including a packet that contains a
conversion variable, the data
corresponding to the conversion
variable cannot be converted to binary
numbers.
• When data are received by the protocol
including a packet that contains an error
check code (ASCII hexadecimal or
ASCII decimal), the data corresponding
to the error check code cannot be
converted to binary numbers.
PRO
• Confirm the message sent from the
external device, correct it, and restart
the communication.
• 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 Conversion, Sign
character, Number of decimals,
Delimiter, or number of digits of the
conversion variable.
• 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 Code type or Data
length of the check code.
• There is an error in the command
(frame) part.
7F21 H
Receive header
area error
• An ASCII code that cannot be
converted to binary code was received.
PRO
• Check and correct the external device
transmit message and restart data
communications.
7F22 H Command error
• A nonexistent command or device was
designated.
• The remote password length is wrong.
PRO
• Check and correct the external device
transmit message and restart data
communications.
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