Rockwell Automation 1756-L6x_L7x ControlLogix System User Manual - Manual (Page 178)

178 Rockwell Automation Publication 1756-UM001O-EN-P - October 2014
Chapter 12 Redundant Systems
System Considerations When you are configuring a redundant ControlLogix system, these
considerations to modules in the redundant chassis must be made.
For complete information about to design and plan modules for use in your
redundant ControlLogix chassis, see the ControlLogix Enhanced Redundancy
User Manual, publication
1756-UM535 .
Items in Primary and
Secondary Chassis Consideration
ControlLogix controller • When configured for redundancy, the secondary controller automatically receives
and buffers data.
• A redundant controller uses twice as much data memory and I/O memory space as
a nonredundant controller.
• A redundant controller has a longer scan time than a nonredundant controller.
• The ControlLogix Enhanced Redundancy User Manual, publication 1756-UM535 ,
provides detailed information about minimizing the scan time impact.
• You do not need a redundancy-specific version of Logix Designer software, but it
must match your Enhanced Redundancy System revision level.
Communication modules • In an enhanced redundancy system, as many as seven communication modules can
reside in a controller chassis in any combination of EtherNet/IP modules and
ControlNet modules.
• To connect to other networks, bridge through another ControlLogix chassis outside
the redundant system.
• For best results, use a separate network for HMI and I/O communication.
I/O modules • All I/O is remote from the redundant controller chassis.
• Beginning with Enhanced Redundancy System revision 19.50, EtherNet/IP
networks in redundant systems can be used for remote I/O or produced/consumed
data.
Redundant power supplies The 1756-PA75R and 1756-PB75R redundant power supplies provide reliable chassis
power.
Redundant ControlNet media Redundant media provide more reliable ControlNet communication.