Rockwell Automation 1768-EWEB EtherNet/IP Web Server Module User Manual - Manual (Page 121)

121 Publication ENET-UM527E-EN-P - October 2006
Appendix
A
Use the Web Server Module To Connect
Over Ethernet
About This Appendix A connection is a communication association between two devices.
The web server modules uses different types of communications
connections. Since connections use internal module resources, the
web server module has limits on the number of connections it
supports.
This appendix discusses these types of connections.
• CIP connections
The web server module uses CIP connections to read data view
data, to communicate with a module in the local chassis, and to
communicate with another EtherNet/IP module. For example,
CIP connections are used when a Logix controller sends
messages through the web server module to another Logix
controller over Ethernet.
• TCP/IP connections for EtherNet/IP communications
As specified by the EtherNet/IP protocol, when the web server
module communicates with another EtherNet/IP module, it first
establishes a TCP connection with the target module. The TCP
connection is then used for CIP connected and unconnected
messages. Multiple CIP connections may be established over a
single TCP connection.
CIP Connections Connections are allocations of resources that provide more reliable
communications between modules than unconnected messages.
Examples of web-server functions that use CIP connections include:
• data views (one connection per controller slot).
• sending email initiated by controller MSG instructions.
• bridging messages through the web server module.
Topic Page
CIP Connections 121
TCP Connections 123