User Manual Manual

166 Rockwell Automation Publication 1757-UM012A-EN-P - July 2011
Appendix D Connections
Table 2 6 shows an example of counting your ControlNet network connections.
To determine the number of connections and packets per second for an Ethernet
network, use the EtherNet/IP Capacity tool at http://www.ab.com/go/iatools
.
In Example 1, if a 1756-CNB ControlNet bridge module is being used, the
network could be considered fully loaded because this module supports 64
connections.
In Example 2, if a 1756-CNB ControlNet bridge module is being used, the
network could be considered fully loaded and even too close to the connection
limit. We recommend that you have a number of spare connections for additional
connections that may occur.
Table 26 - ControlNet Network Examples
Example 1 Example 2
Number of 1757-FFLDC linking devices 3 10
Number of Logix Blocks used per
linking device
16 4
Class 1 connections
(1 per Logix Block)
48 40
Class 3 connections
(2 per linking device)
620
Controller connection to the ControlNet bridge or
interface module
11
Total connections 55 61