The Simplex 4090-9001 is a supervised Individual Addressable Module (IAM) designed to monitor normally open dry contacts and associated end-of-line resistors on Simplex IDNet or MAPNET II communication circuits. It receives both power and data over a two-wire addressable loop and provides a single addressable input point to the fire alarm control panel.

The module supports Class B supervised monitoring and allows up to 500 ft (152 m) of wiring between the IAM and the end-of-line resistor (400 ft when used with 2081-9044 overvoltage protectors). It is housed in a thermoplastic enclosure with screw terminals and includes a visible LED that flashes to indicate communication status.

The 4090-9001 mounts in a standard single-gang electrical box and is suitable for indoor environments up to 158°F (70°C), including attic or similar spaces.