Omron CJ1W-ETN21 - 04-2009 Operation Manual page 44

Overview of Communications Functions
Executing CMND(490)
Improved TCP Socket
Interface
Another way to use socket services is to request a UDP or TCP socket ser-
vice by sending a FINS command to the Ethernet Unit by executing
CMND(490) from the CPU Unit. When the Ethernet Unit receives the socket
service request, it returns a response to the CPU Unit to confirm that it
received the request, and then begins the requested processing. When the
processing is completed, the results are stored in the Results Storage Area in
the CPU Unit.
Eight TCP ports and eight UDP ports can be used.
The TCP socket interface has been improved. The size of received data accu-
mulated in the reception buffer is now stored, and a Data Received Flag has
been added, enabling the TCP socket's receive program to be executed after
the required data has been accumulated in the Ethernet Unit's reception
buffer. The keep-alive setting has also been enabled for TCP socket services.
UDP protocol
UNIX computer, etc.
(node with socket
services interface)
Ethernet
TCP/UDP
Ethernet Unit
protocol
CS/CJ-series
CPU Unit
FINS
commands
TCP protocol
FINS
responses Results Storage
Area
Processing
results
Socket interface
Ethernet Unit CS/CJ-series
CPU Unit
Section 1-5
CMND
19