The Allen-Bradley 1747-BSN is a backup scanner module. The 1747-BSN backup scanner is available with redundancy for remote I/O (RIO). The 1747-BSN is equipped with RS-232 channel switching for communication with devices such as operator interfaces. This module also has a DH+ link. This module is a set of complementary modules, with one module located in the main system and other modules in the secondary or backup system. The main module controls all the remote I/O operations. The secondary module is available to take over the control if something goes wrong on the primary module. The backup scanner has the ability to switch between 2 communication channels. The first channel can be configured as RIO or DH +. The second channel is used to replace the RS-232/485 channels to provide connections for the operator's electronic interface. DH+/RIO and RS-232/485 channels can be used together.

The Allen-Bradley 1747-BSN provides a High-Speed Serial Link (HSSL) for writing retentive data from the primary processor to secondary processor. In addition, this module has a Local Serial Link (LSL) to convey status information between several 1747-BSN modules residing on the same chassis. The 1747-BSN has a backplane current consumption of 800 mA at 5V. The Allen-Bradley 1747-BSN’s operating temperature is 32-140 °F and its storage temperature is -40-185 °F. The relative humidity is from 5-95%, noncondensing. Please remember to make sure that you have set the DIP switch correctly before installing the scanner.