Allen-Bradley 1747-SN Remote IO Scanner Module

The Allen-Bradley 1747-SN Remote I/O Scanner Module is the SLC 500 PLC’s master on the Remote I/O (RIO) network, handling communications between the central controller and distributed I/O racks. Compatible with SLC 5/02, 5/03, 5/04, and 5/05 processors, it translates PLC-5 addressing to RIO addressing and organizes the remote I/O image into M0 and M1 memory areas with the G-file defining address mapping. The scanner supports RIO data transfer at 57.6 Kbaud or 115.2 Kbaud, enabling either standard or higher-speed operation for larger installations. A 1/2-watt terminating resistor is included and must be installed across line 1 and line 2 at each end of the RIO link to ensure proper signal integrity. The 1747-SN’s remote I/O image is divided into logical racks, providing scalable I/O coverage when paired with AB remote I/O adapters and remote rack modules. The SLC 500 I/O data table has a practical limit of 4,096 I/O points, and the 1747-SN enables this capacity to be extended across distributed I/O while remaining configurable from RSLogix 500. In typical setups, the scanner sits in the SLC chassis and communicates with remote racks via the RIO link, with the controller issuing reads and writes to the remote modules and the scanner handling data transfer and diagnostics on the network.