Allen-Bradley 1756-CNB/E, User Manual

Page: 174 / 186

Publication 1756-UM523F-EN-P - December 2006
174 Series B ControlNet Bridge Modules
The loss of communication happens on the first switchover after you
download the project to the redundant controller.
•
You lose communication with the remote chassis and any
devices to which you were bridging via the chassis, such as the
remote I/O modules.
•
During the communication loss, the I/O modules go to their
configured state for a communication fault.
•
The communication loss is temporary. Communications restore
themselves.
To prevent this situation, use series D or series E ControlNet Bridge
modules.
Communication Stoppage
While Using a Series B
ControlNet Bridge Module All communication on a ControlNet network could stop if the lowest
node is a 1756-CNB/B or 1756-CNBR/B module. This happens if you
unplug or break the tap of the module while it is turned on.
Module Corrective Action
To prevent this situation, use series D or series E ControlNet Bridge
modules.
If Then
Tap of a series B ControlNet Bridge module
becomes unplugged or broken 1. Turn off the power to the module.
2. Replace the tap.
3. Turn on the power to the module.
Communication on the network stops
because of an unplugged or broken tap Cycle power to each primary controller on
the network.