User manual

214 Publication ENET-UM001I-EN-P - January 2010
Appendix C EtherNet/IP Network Connections
The Logix5000 controller supports 250 connections, but the limit of
connections ultimately resides in the communication module you use for the
connection. If a message path routes through a communication module or
card, the connection related to the message also counts towards the
connection limit of the communication module or card.
TCP Connections
An EtherNet/IP module uses one TCP connection for each IP address to
which the EtherNet/IP module is connected. Multiple CIP connections can
go through a single TCP connection. Examples of TCP connections include:
• HMI (human-machine interface) to a controller that supports
EtherNet/IP comm
unication.
•
Logix MSG instruction to a controller or workstation.
• OPC or DDE accessing a controller.
• I/O data.
• produced or consumed tags.
The 1756-ENBT, 1788-ENBT, and 1794-AENT modules eac
h
support 64
TCP connections.
A TCP connection is established when a controller
initiates one. For example,
when controller A sends a MSG to controller B, the Ethernet modules
associated with controller A and controller B both have a TCP connections.
Additionally, if controller B initiates a MSG to controller A, both Ethernet
modules now have 2 TCP connections in use. For any further
commuinications, such as MSG exchanges, producing tags, or I/O
communication, bridging between Ethernet module associated with
controllers A and B modules, no more TCP connections are required.
Types of CIP Connections
CIP Connection Type Description
Bridged A bridged connection is a connection that passes through the EtherNet/IP module. The end point of the
co
nnection is a module other than the EtherNet/IP module.
Example: a connection from a controller through a 1756-ENBT module to another controller
.
Rack-optimized A rack-optimized connection is a connection to a rack or assembly object in the EtherNet/IP module. Data
from selected I/O modules is collected and pro
duced on one connection (the rack-optimized connection)
rather than on a separate direct connection for each module.
Direct A direct connection is a connection from a controller to a spec
ific
I/O module, as opposed to a rack-optimized
connection.