Mitsubishi MELSEC-F User Manual page 257

11 TROUBLESHOOTING
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NOTE
Depending on the restrictions of the buffers of the local station and external device,
data may be divided for communication.
Data received separately is restored (reassembled) by the Ethernet module to be
communicated using the fixed buffer, etc. The received data is restored
(reassembled) based on the data length in the communication data.
The Ethernet module performs the following processing if data among the
communication data is incorrect.
(1) When communication is performed using fixed buffer (with procedure)
(a) If the data length specified immediately after the subheader is smaller than
the amount of text data received
1) The data immediately following the part of the text data equivalent to
the data length specified immediately after the subheader will be
regarded as the next message.
2) Since the header of each message will be a subheader, the Ethernet
module performs processing according to the code in the subheader.
3) If the subheader contains a code that is not recognized by the
Ethernet module, the Ethernet module will send a response to the
external device notifying it of abnormal completion.
Data sent by an external device
Sub
header
At this point, the Ethernet module returns a response containing a code
obtained by changing the most significant bit of the code processed as
subheader to 1.
For example, if the subheader field of a command is 65
the response will become E5
Data determined by the Ethernet module
(First data)
(Second data)
Sub
header
.
H
MELSEC-F
This section is processed as a subheader.
, the subheader of
H
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