Application examples, 2-3 application examples, Responding to computers with changed ip addresses – Omron CS1W-ETN21 User Manual

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IP Addresses in FINS Communications

Section 5-2

5-2-3

Application Examples

Responding to Computers with Changed IP Addresses

FINS/UDP
Communications Method

With FINS/UDP, whether using the automatic conversion method (dynamic),
the IP address table method, or the combined method, remote FINS node
addresses and remote IP addresses in the internal table are changed after
FINS messages are received. Therefore, even when a FINS command has
been received from a personal computer (a DHCP client computer) for which
the IP address is dynamically changed, a response can still be sent back to
the computer (the DHCP client computer) from which the command origi-
nated.

FINS/TCP
Communications Method

With FINS/TCP, FINS node addresses and IP addresses in the internal table
are changed with each connection that is established. Therefore, even when a
FINS command has been received from a personal computer (a DHCP client
computer) for which the IP address is dynamically changed, a response can
still be sent back to the computer (the DHCP client computer) from which the
command originated.

Note

Automatic IP Address Setting by DHCP Service
DHCP service is a method whereby a DHCP server collectively manages all
of the IP address in a network.
Nodes that are functioning as clients acquire IP addresses from the DHCP
server whenever the system is started. Therefore, at a personal computer
using the DHCP service, IP addresses may be different with each system
startup.
DHCP service is mainly used for automatic settings in devices such as per-
sonal computers that are used for client applications. Nodes used for server

Personal computer (client)

IP address changed
(acquired from DHCP server when connected)

FINS command sent

IP address

FINS command

FINS response

Ethernet

Response sent back to
changed IP address

Ethernet Unit
(with fixed IP address)