Allen-Bradley 1756-CN2R

You can use the 1756-CN2R series B modules for standalone or 

redundant control. For standalone control, only one set of modules is 

required. For redundant control, two ControlLogix chassis are 

populated with identical pairs of modules called partners. The chassis 

that performs active control is called the primary chassis and the 

modules in the chassis are called primary modules. The other chassis 

is called the secondary chassis and the modules in the chassis are 

called secondary modules.

These installation instructions discuss both standalone and redundant 

control; read them carefully to distinguish the procedures and 

requirements for each type of control.

If you use redundant control, you must select the same ControlNet 

network address for each set of partner modules (primary and 

secondary). You must also place the partner modules in the same 

corresponding slots in their respective redundant-control chassis 

pair.

The 1756-CN2 and 1756-CN2R series B modules are supported in 

both the local chassis (primary and secondary) and the remote 

chassis (I/O chassis) of a ControlLogix redundancy system, 

revision 16.5x.

The 1756-CN2 series B module is a keeper capable module. This 

means that, if the module has a valid configuration and has the 

lowest address among the keeper capable nodes on the network, it 

becomes the Master Keeper. The Master Keeper is the node that 

distributes network configuration information to other nodes as the 

network is formed or as nodes are added to the network.