Allen-Bradley 1756-CNB - System Layout and IO Placement

Publication 1756-UM523F-EN-P - December 2006
28 Design the System
Laying Out the System
ControlLogix Redundancy Requirements and Recommendations
C
N
B
E
N
B
I/O Modules
D
N
B
D
H
R
I
O
M
V
I
Other Networks
Remote location for all:
• I/O
• DNB, DHRIO, & MVI
communication modules
Assign the lowest node numbers
to nonredundant nodes.
An additional node can be:
• a second CNB module in the same remote chassis or in a different remote chassis.
• any other ControlNet device (not required to be keeper capable).
ControlNet network:
• Set NUT ≤ 90 ms
• Set RPIs ≤ 375 ms
• If multiple ControlNet
networks, set NUTs
≤ specified values.
For unscheduled communication,
use ≤ 4 PanelView terminals per
controller.
At least 2 nodes in
addition to the CNBs in
the redundant chassis
Multiple redundant chassis
pairs are OK.
Use separate networks for unscheduled and scheduled
communication.
• For unscheduled communication (HMI, workstations,
message instructions), use either an EtherNet/IP or a
ControlNet network.
• For scheduled communications (I/O, produced/consumed
tags), use a ControlNet network.
To connect a computer to the
network via an NAP, use a remote
node.
EtherNet/IP ControlNet
ControlNet
or
Unscheduled Communication
Scheduled Communication