Rockwell Automation Publication CNET-UM001F-EN-P - February 2018  11 
Chapter 1 
ControlNet Overview 
The ControlNet network provides high-speed transmission of time-critical 
I/O and interlocking data and messaging data. This data transfer capability 
enhances I/O performance and peer-to-peer communication in any system or 
application. 
The ControlNet network is highly deterministic and repeatable and remains 
unaffected as devices are connected or disconnected from it. This ensures 
dependable, synchronized, and coordinated real-time performance. 
The ControlNet network is most often used in these ways: 
•  As the default network for the ControlLogix platform 
•  As a backbone to multiple distributed DeviceNet networks 
•  As a peer interlocking network 
This chapter describes how you can use ControlNet modules in a network 
control system. 
Topic  Page 
Use ControlNet Communication Modules in a Control 
System on page 11 
9 on page 11 
Bridge Across Networks on page 13  11 on page 13 
Exchange Information on a ControlNet Network on page 16  14 on page 16 
ControlNet Network Capacity and Topology on page 22  21 on page 22 
 
You can fit various ControlNet modules into your control system. 
Figure 1 on page 10 shows the following: 
•  The controllers produce and consume tags among themselves. 
•  The controllers initiate MSG instructions that send/receive data or 
configure devices. 
•  The computer uploads and downloads projects to the controllers. 
•  The computer configures devices on the ControlNet network and 
configures the network itself. 
Communication 
Modules in a 
Control System