Rockwell Automation 5720 DriveLogix System - Manual (Page 179)

Publication 20D-UM002C-EN-P - November 2003
Communicating with Devices on a ControlNet Link 7-33
You can configure the 1756-CNB module to use no connection. This is useful
if you configure all direct connections to their associated I/O modules and do
not need a rack-optimized connection.