Rockwell Automation 1768-EWEB EtherNet/IP Web Server Module User Manual - Manual (Page 128)

Publication ENET-UM527E-EN-P - October 2006
128 Socket Interface
Typical Sequence of Transactions For a TCP Client
The following diagram shows a typical sequence of socket interface
transactions with the Logix controller acting as a TCP client. Each
transaction between the Logix controller and the web server is a MSG
instruction.
The following example shows the Logix controller sending data to a
device and then the device sending a response. This is a typical
sequence of transactions. Depending on the application protocol, the
device could instead initiate sending data to the Logix controller once
the connection is open.
Additionally, each Write does not require an application response or
acknowledgement. The application protocol determines the exact
sequence of application transactions.
Logix
Controller
Web Server Module
10.10.10.10
Device
10.10.10.11
Accept
Connection
Receive
Data
Send
Data
Open TCP
Connection
Data = abc
Data = xyz
The response is returned to the
controller as soon as the data is sent.
CreateSocket
CreateSocket Response
Instance = 102
OpenConnection
"10.10.10.11?Port=49200"
OpenConnection Response
Write
Data = abc
Write Response
Read
Read Response
Data = xyz