Allen-Bradley ControlNet Compact GuardLogix 1769, User Manual, Page: 19 / 100

ControlNet Overview Chapter 1
IMPORTANT
RSNetWorx for ControlNet software must be run whenever a
scheduled connection is added to, removed from, or changed in your
system.
Control of Scheduled I/O
Scheduled connections let you send and receive data repeatedly at a
predetermined rate. You can use the 1756-CNB or the 1756-CN2 module to
control scheduled I/O when you use it in conjunction with a ControlLogix
controller. When you place the module in the I/O configuration list of a
ControlLogix controller and configure a second ControlLogix chassis with a
remote 1756-CNB or 1756-CN2 module on the same ControlNet network, you
can perform remote control operations on the I/O, or to a second controller in
the second chassis.
In this case, the ControlLogix controller and the 1756-CN2 module in the local
chassis together act as a scanner, while the 1756-CN2 module in the remote
chassis with the I/O plays the role of an adapter.
Understand the Network Keeper
Every ControlNet network requires at least one module to store programmed
parameters for the network and configures the network with those parameters
when the module is started. This module is called a keeper because it keeps the
network configuration. RSNetWorx for ControlNet software configures the
keeper.
To avoid a single point of failure, a ControlNet network supports multiple
redundant keepers. These ControlNet communication modules are keeper-
capable devices:
•
•
1756-CN2 and 1756-CN2R modules
•
1756-CNB and 1756-CNBR modules
•
1768-CNB and 1768-CNBR modules
•
1769-L32C and 1769-L35CR controllers
•
1784-PCICS and 1784-PKTCS cards
•
1788-CN x cards
PLC-5C module
On a multi-keeper network, any keeper-capable module can keep the network at
any legal node address (01...99). The multi-keeper-capable node with the lowest
node address becomes the active keeper provided it is valid. It has been
configured by RSNetWorx for ControlNet software and that configuration is the
same as that of the first keeper that became active after the network was formed
or reconfigured by RSNetWorx software.
Rockwell Automation Publication CNET- UM001E-EN-P - June 2016 19