Mitsubishi Electric FX3U-ENET-ADP User Manual page 51

FX -ENET-ADP User's Manual
3U
2) Close processing
The purpose of close processing is to disconnect (cancel) the connection with the external device
established by open processing mentioned previously.
Close processing is used when terminating a connection with an external device, changing an external
device of a connection, changing communication conditions, etc.
Perform close processing for connections established by open processing using sequence programs.
Determine the timing of close processing with the external device.
The Ethernet automatically closes the connection in the following cases even if a request for closing is not
given.
a) When the existence confirmation function times out.
b) When a close or RST command is received from an external device.
c) When an active open request is received again from an external device in the open completion
status of TCP.
After returning ACK to the external device, the Ethernet adapter closes the connection when the RST
command is received from the external device.
However, when receiving an active open request again from an external device with a different IP
address or port No., the Ethernet adapter only sends the RST command. (It does not close the
connection.)
6.12 Open Processing/Close Processing of the Connection
6 Introduction of Functions
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A