Overview

The 1747-BSN Backup Scanner Module provides a high-speed communication

channel between two modular SLC 500™ (5/02 or higher) processors. The 1747-

BSN backup system uses a set of modules, with one or more 1747-BSN modules

residing in the primary system and one or more complementary modules in the

secondary or backup system. The primary system controls the operation of

remote I/O, while the secondary system monitors www.abb-drive.com communications via the highspeed

serial link (HSSL) and is available to take over control in the event of a

fault in the primary system.

Configuration Errors

The module reports the following configuration errors by flashing the fault LED:

• two 1747-BSN modules are configured with the same address

• LSL addresses are not consecutive (addresses must be numbered 0, 1, 2,etc.)

• last LSL switch is not set in the last module in the link

• last LSL switch is set in a module that is not the last in the link, or

• primary and secondary modules do not have the same configuration settings

(secondary module shows the configuration error)

Switchover Conditions

The 1747-BSN module transfers control from the primary to the secondary

processor (switchover) if one of the following fault conditions occurs in the

primary system:

• power failure

• major fault in the processor

• 1747-BSN module fault

• primary processor mode change from Run to Program

Note: In order for switchover to occur, both primary and

secondary modules must be working without faults prior

to the event that triggers the switchover.