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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 reliabili ty 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 virtua l cir-
cuit) with the destination node, providing a highly reliable commun ications
service.
7. FINS (Factory Interface Network Service)
A protocol that sends messages between PLCs on any of various OM RON
FA networks. To ensure that transmitted messages arrive at the destination
node, it is necessary to program special measures suc h 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 computer s on
the same Ethernet network by executing SEND(090), RECV(098), or
CMND(490) instructions in the ladder diagram program. This enables vari ous
control operations such as the reading and writing of I/O me mory 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