Rockwell Automation 1794-L34 FlexLogix Controller System User Manual - Manual (Page 24)

Publication 1794-UM001G-EN-P - January 2007
24 Communicate over Networks
Connections over EtherNet/IP
You indirectly determine the number of connections the controller
uses by configuring the controller to communicate with other devices
in the system. Connections are allocations of resources that provide
more reliable communications between devices than unconnected
messages.
All EtherNet/IP connections are unscheduled. An unscheduled
connection is a message transfer between controllers that is triggered
by the requested packet interval (RPI) or the program (such as a MSG
instruction). Unscheduled messaging lets you send and receive data
when needed.
The 1788-ENBT card supports 32 CIP connections over an EtherNet/IP
network. With these controllers, the number of end-node connections
they effectively support is dependent on the RPI of the connection:
In the table above, with an RPI of 32 ms and greater, the EtherNet/IP
card effectively supports 25 communications connections. In this case,
the remaining 7 connections can be used for non-I/O purposes.
For more information... The EtherNet/IP Modules in Logix5000 Control Systems User Manual,
ENET-UM001 provides information on how to:
• configure an EtherNet/IP communication module
• control I/O over EtherNet/IP
• send a message over EtherNet/IP
• produce/consume a tag over EtherNet/IP
• monitor diagnostics
• calculate controller connections over EtherNet/IP
The Logix5000 Controllers Design Guidelines Reference Manual,
1756-RM094 provides guidelines on optimizing a control application
on an EtherNet/IP network.
If the RPI is: The EtherNet/IP card effectively
supports a maximum of this many
communication connections:
2 ms 2
4 ms 5
8 ms 10
16 ms 18
32 ms + 25