The M22-ADC4 is a digital input module manufactured by Eaton. The module is designed to connect digital signals such as switches, reed contacts, and open-collector outputs to an M22 series programmable logic controller. It provides 16 digital inputs and is compatible with a 24 V DC power supply. It has LED status indicators for each channel and comes with a removable terminal block for easy field wiring connections. The module is connected to the system using an M22 power supply and an M22 bus connector. It is rated for use in a Category 3 as per EN/IEC 61131-2 environment.