Allen-Bradley 1756-CNB User Manual page 176

176 Series B ControlNet Bridge Modules
Restriction
If the lowest node is a 1756-CNB/B or
-CNBR/B module, removing a tap or
breaking a cable could stop all
communications over the network.
Publication 1756-UM523F-EN-P - December 2006
Description
If the lowest node on a ControlNet network is a 1756-CNB/B or 1756-CNBR/B module, all
communications over the network could stop if a tap to the 1756-CNB or -CNBR/D module is
disconnected or breaks and then is replaced while power is still applied to the the 1756-CNB/B or
-CNBR/D module.
If a tap to a 1756-CNB/B or -CNBR/B module becomes disconnected or broken, take these actions.
1. Turn off the power to the 1756-CNB/B or -CNBR/B module.
2. Replace the tap.
If a communication failure occurs because of a disconnected or broken tap, cycle power to each
primary controller on the network.
To prevent this situation, use a 1756-CNB/D/E or -CNBR/D/E module as your lowest node on the
network.