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Overview of Communications Functions Section 1-5
5. UDP (User Datagram Protocol)
Performs data communications. Data resends, priority control, flow control,
and other measures to ensure communications reliability are not per-
formed for UDP communications, so the transmitted data may not arrive at
the destination node. To increase reliability, it is necessary to program spe-
cial measures into the user applications.
6. TCP (Transmission Control Protocol)
Performs communications after establishing a connection (i.e., a virtual cir-
cuit) with the destination node, providing a highly reliable communications
service.
7. FINS (Factory Interface Network Service)
A protocol that sends messages between PLCs on any of various OMRON
FA networks. To ensure that transmitted messages arrive at the destination
node, it is necessary to program special measures such as retry process-
ing into the user's applications.
8. FTP (File Transfer Protocol)
Transfers data files.
9. SMTP (Simple Mail Transfer Protocol)
A communications protocol for sending e-mail by TCP/IP.
10. POP3 (Post Office Protocol Ver. 3.0)
A communications protocol for receiving e-mail by TCP/IP.
11. SNTP (Simple Network Time Protocol)
A communications protocol for automatic clock adjustment by UDP/IP.
12. DNS (Domain Name System)
A communications protocol for determining IP address names according
to UDP/IP and TCP/IP.
1-5 Overview of Communications Functions
1-5-1 FINS Communications Service
Basic Functions FINS commands can be sent to or received from other PLCs or computers on
the same Ethernet network by executing SEND(090), RECV(098), or
CMND(490) instructions in the ladder diagram program. This enables various
control operations such as the reading and writing of I/O memory between
PLCs, mode changes, and file memory operations.
Ethernet
Ethernet Unit Ethernet Unit Ethernet Unit
User program
IP
UDP or TCP
FINS IP FINS
CS/CJ-series
CPU Unit
UDP or TCP
SEND(090),
RECV(098), or
CMND(490)
instruction
