Omron CJ1W-ETN21 operation manual Using the FINS/UDP and FINS/TCP Methods

Overview of FINS Communications Section 7-1

7-1-2 Using the FINS/UDP and FINS/TCP Methods

It is recommended that FINS/UDP and FINS/TCP be used as follows:

•When remote devices do not support the FINS/TCP method:

Use the FINS/UDP method for FINS communications with those devices.

•When FINS nodes are connected on the same Ethernet segment: Use the FINS/UDP method between those nodes.

Note FINS/UDP offers a slight advantage in performance.

•When FINS nodes are connected over multiple IP network layers: Use the FINS/TCP method between those nodes.

Note FINS/TCP offers superior communications quality.

•When the quality of connections is unreliable, as with wireless LAN: Use the FINS/TCP method between those nodes.

Note FINS/TCP offers superior communications quality.

7-1-3	FINS Communications Service Specifications for Ethernet
	Item		Specifications
Number of nodes		254
Message length		2,012 bytes max.
Number of buffers		192
Protocol name		FINS/UDP method	FINS/TCP method
Protocol used		UDP/IP	TCP/IP
		The selection of UDP/IP or TCP/IP is made by means of the FINS/TCP Tab in the CX-Pro-
		grammer's Unit Setup.
Number of connections		---	16
Port number		9600 (default)	9600 (default)
		Can be changed.	Can be changed.
Protection		No	Yes (Specification of client IP addresses when Unit is used as a
			server)
Other		Items set for each UDP	Items set for each connection
		port	• Server/client specification
		• Broadcast
			• Remote IP address specification
		• Address conversion	When client: Specify remote Ethernet Unit (server) IP address
		method
			When server: Specify IP addresses of clients permitted to con-
			nect
			• Automatic FINS node address allocation:
			Specify automatic allocation of client FINS node addresses
			• Keep-alive
			Specify whether remote node keep-alive is to be used.
			TCP/IP Setting:
			• Remote node keep-alive time.
Internal table		This a table of correspondences for remote FINS node addresses, remote IP addresses, TCP/
		UDP, and remote port numbers. It is created automatically when power is turned ON to the
		PLC or when the Ethernet Unit is restarted, and it is automatically changed when a connection
		is established by means of the FINS/TCP method or when a FINS command received.
		The following functions are enabled by using this table.
		• IP address conversion using the FINS/UDP method
		• Automatic FINS node address conversion after a connection is established using the FINS/
		TCP method
		• Automatic client FINS node address allocation using the FINS/TCP method
		• Simultaneous connection of multiple FINS applications

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