Omron V750 series, Network Connection Manual

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2. Terms and Definition
2
2. Terms and Definition
Terms Explanation and Definition
IP address Ethernet uses an IP address to perform communications.
The IP address (Internet Protocol address) is an address that is used to
identify a node (host computer or controller, etc.) on Ethernet.
IP addresses must be set and managed so they do not overlap.
Socket A socket is an interface that allows you to directly use TCP or UDP
functions from the user program. The socket services enable data
exchange with destination nodes. The NJ-series Machine Automation
Controller performs socket communications by using the standard socket
service instructions.
Connect processing/
Accept processing Open processing is executed on each node to connect the TCP socket.
The open method depends on whether the node is opened as a server or
client.
In this document, the processing executed to open a node as a client is
called "connect processing" and the processing executed to open as a
server is called "accept processing".
Keep-alive function When the keep-alive function is used with TCP/IP socket services, the
keep-alive communications frame is used to check the status of the
connection with the destination node (either a server or client) if there are
no communications during the specified time interval.
Checks are executed at a certain interval, and if there is no response to
any of them then the connection is terminated.
Linger function This is an option for the TCP socket that enables immediate connect
processing using the same port number without waiting until the port
number opens after RST data is sent when the TCP socket closes.
If the linger option is not specified, FIN data will be sent when a TCP
socket is closed, and then approximately 1 minute will be required to
confirm the transmission and perform other closing management with the
destination node. Therefore, it may not be possible to immediately use
TCP sockets with the same port number.