Socket Services - Omron CJ1W-ETN21 - 04-2009 Operation Manual

Overview of Communications Functions
1-5-2

Socket Services

Manipulating Dedicated
Control Bits
18
• Even if the IP address and UDP port number of the host computer (a
DHCP client computer) are changed, it is still possible for the host com-
puter to send FINS commands to PLCs on the Ethernet network and to
receive responses. When UDP is used, either the automatic generation
(dynamic) method or the IP address table method must be selected for IP
address conversion. When TCP is used, changes in IP address and TCP
port numbers are handled automatically.
• Multiple FINS applications (CX-Programmer and user-created application
programs) at the same computer can be connected online to a PLC via
Ethernet (using either TCP/IP or UDP/IP).
The socket services allow devices on the Ethernet to send and receive vari-
ous data using either the UDP or TCP protocol.
One way to use socket services is to set the required parameters in the
parameter area allocated in the DM Area, and then to request particular UDP
or TCP socket services by turning ON dedicated control bits in memory. When
the Ethernet Unit has completed the requested process, the same bit is
turned OFF to provide notification. Data that is sent or received is automati-
cally handled according to the I/O memory locations specified in the parame-
ter area.
There is no need to execute the CMND(490) instruction or to monitor the com-
pletion timing and actual processing of the instruction, so this helps to simplify
ladder programming.
A total of eight ports (UDP and TCP combined) can be used for socket ser-
vices.
Starting with unit version 1.5, the performance of sending and receiving has
been improved by using the option settings.
UNIX computer, etc.
(node with socket
services interface)
Ethernet
TCP/UDP Ethernet Unit
protocol
CS/CJ-series
CPU Unit
Service request switch
TCP/UDP
Parameters
protocol
Ethernet Unit CS/CJ-series
CPU Unit
Section 1-5