The 2541 Redundant Processor Manager (RPM) provides an automatic

backup solution for 2500 Series® PLCs. If the active PLC fails, the RPM

will automatically switch the remote I/O to the standby PLC.

Transfer to the standby PLC is bumpless. All remote I/O updates are

mirrored to the standby PLC. In addition, up to 4096 words of user-

defined critical data can be transferred from the active PLC to the 

standby PLC every scan.

Other non-critical data can be transferred over several scans.

The RPM can also switch up to two serially attached operator interface

devices.

IMPORTANT NOTE: Due to extensive component obsolescence issues

and insufficient demand to justify a re-engineering effort, this product

has been matured.  For users needing PLC redundancy in the future,

we have a solution planned based on our new Janus Programmable

Automation Controller which uses two Janus PLCs and a Modbus relay

that switches Remote I/O and Profibus networks from the primary PLC

to the backup in case of a Processor failure.