The Allen-Bradley 1747-BSN is a Backup Scanner module designed for the SLC 500 programmable controller platform. It provides critical redundancy for remote I/O (RIO) communication links. Operating in tandem with a primary 1747-SN Remote I/O Scanner, the 1747-BSN monitors the health of the primary scanner and its communication network. In the event of a failure, the 1747-BSN automatically and seamlessly takes control of the I/O link, ensuring continuous operation and minimizing system downtime. This module is essential for high-availability applications where control system integrity is paramount. It mounts in any available slot of a 1746 I/O chassis and features status indicators for easy diagnostics.