Application Examples - Omron SYSMAC CS1W-ETN21 Operation Manual

IP Addresses in FINS Communications
5-2-3

Application Examples

Responding to Computers with Changed IP Addresses
FINS/UDP
Communications Method
FINS/TCP
Communications Method
Note
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.
Personal computer (client)
IP address changed
(acquired from DHCP server when connected)
FINS command sent
IP address
IP address
Response sent back to
changed IP address
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.
Personal computer (client)
IP address changed
(acquired from DHCP server when connected)
FINS command sent
IP address
IP address
Response sent back to
changed IP address
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
FINS command
FINS response
FINS command
FINS response
Section 5-2
Ethernet
Ethernet Unit
(with fixed IP address)
Ethernet
Ethernet Unit
(FINS/TCP server; with
fixed IP address)
105