Schneider Electric AS-B840-108 Programmable Logic Controller Module

Schneider Electric AS-B840-108 is an eight-point reed-relay output module for the Modicon 800-Series I/O family, delivering eight independent NO/NC outputs for discrete control of relays, indicators, and similar loads. Each output uses a mercury-wetted relay, isolated from the I/O bus and from the other outputs, with RC snubbers and internal protection to guard against arcing and overload; the module is rated to switch AC or DC loads from 0 to 230 VAC (47–63 Hz) or 0 to 300 VDC, with a per-point current capability of up to 2 A and an overall module current limit of 24 A (up to 100 VA per output). The AS-B840-108 occupies a single backplane slot and weighs about 1.19 kg (2.62 lb). It requires power from the backplane via on-board rails, typically +5 V at 67 mA and +4.3 V at 400 mA. The eight outputs are organized as eight groups (one output per group), making it suitable for applications needing robust discrete switching in manufacturing automation, packaging lines, material handling, and process instrumentation when paired with a compatible Modicon controller. This I/O module is part of Schneider Electric’s Modicon 800-Series ecosystem, designed for use with 984-series controllers and other 800-Series I/O modules to provide reliable, isolated switching for field devices while integrating with the standard 800-Series I/O bus.