Bulletin 1756 ControlLogix® Redundancy Modules support fully redundant controller architectures with no additional programming required. Programs are cross-loaded automatically from the primary to the secondary controller. The primary automatically updates the secondary with data changes to maintain controller synchronization. If the primary fails, control switches to the secondary automatically, and highest priority functions are guaranteed a ‘bumpless transfer.' Controller redundancy is transparent to any devices connected over an EtherNet/IP™ or ControlNet™ network. Select the ControlLogix extreme environment redundancy module for applications that must run in extreme environments