The Allen-Bradley 1771-SN Sub I/O Scanner Module is a PLC-5 I/O expansion device that serves as the sub I/O scanner interface between a PLC-5 controller and remote I/O devices. It enables scalable I/O by supporting up to 896 digital remote I/O points and up to 16 Remote I/O adapters on a universal remote I/O link. This model operates at 5 V DC and draws about 1.2 A, reflecting its power requirements for field wiring and logic. In PLC-5 installations, the 1771-SN functions as a sub I/O scanner module, interfacing with remote I/O via the Remote I/O protocol to collect inputs and distribute outputs.
