The 1771-SDN is a DeviceNet scanner module that belongs to the 1771 series of I/O modules and it is manufactured by Allen-Bradley. The main function of this module is to allow data exchange between the PLC processor and the DeviceNet devices. The Allen-Bradley 1771-SDN DeviceNet Scanner Module is compatible with series A, B, and in some cases with a C version. Prior to the installation of the scanner module, users need to have a personal computer with the Microsoft Windows 95 OS or a newer operating system, the RSLogix 5 software and the RSNetWorx for DeviceNet software, version 2.22 or later. The scanner module is located inside the I/O module chassis. The hardware components required to install the Allen-Bradley 1771-SDN DeviceNet Scanner Module are a local I/O chassis with the PLC processor, an extended local chassis with an adapter module, and a remote chassis. These chassis need to have adapter modules in the leftmost slot.

The Allen-Bradley 1771-SDN DeviceNet Scanner Module communicates through devices with strobe, poll, change-of-state, and cyclis messages. These messages are used to solicit data to other devices. Data received from different devices can be mapped and routed into different module memory locations. Although the installation of the module is not difficult, the technician should be aware of the connection and programming of the module in order to guarantee correct functioning. In order to program the scanner module, the RSLogix 5 software works by means of the included CD.