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Overview of FINS Communications Section 5-1
5-1 Overview of FINS Communications
The FINS communications service enables client control of operations such
as reading or writing server PC memory area data without the need to pro-
gram these operations into the server PC user program. The Ethernet Unit
uses a dedicated UDP/IP port to execute the FINS communications service.
(Refer to FINS UDP Port Number under 4-2-1 Settings.)
5-1-1 Communications On an Ethernet Network
Data is sent and received as UDP packets on an Ethernet network. The FINS
port number (default value: 9600) set in the CPU Bus Unit System Setup is
used for FINS communications. (Refer to 4-2 CPU Bus Unit System Setup.)
When a FINS command is issued from the Ethernet Unit, the IP address is
found from the FINS address specified by CMND(490). For details, refer to 3-
1 Before Operation.
Note The UDP/IP protocol does not provide communications control to ensure
communications reliability. Consequently, the FINS communications services
using the UDP/IP protocols cannot guarantee that any message arrived safely
and unaltered at the destination. Methods to ensure reliability, such as retries
and appropriate processing of FINS responses, must be programmed into the
user application.
5-1-2 FINS Communications Service Features
The FINS communications service is a function for controlling operations such
as sending and receiving data, changing modes, and so on, between nodes
on OMRON factory automation networks. It provides the following features.
• Communications instructions are executed in the user program.
Ethernet header
IP header
UDP header
FCS
UDP (User Datagram Protocol) packet
PC
Ethernet Unit
or host computer
UDP packet (FINS command)
Ethernet
UDP packet (FINS response)
Ethernet Unit
PC
FINS frame