Product Description:

The C9900-M979 is an accessory module manufactured by Beckhoff for the C9 PC Accessories series. It functions as a compact EtherCAT field unit that brings emergency-stop wiring and auxiliary signals directly to a Beckhoff Industrial PC. By embedding the bus interface, power inlet, and signal terminations in one enclosure, the device reduces panel depth and simplifies machine layouts in automated cells that place operator safety controls at the machine frame. It is intended for on-machine mounting, allowing the host controller to communicate with peripheral buttons and sensors over a single industrial Ethernet link.

The module is powered from a 24 V DC supply that is delivered through a 4-pin M12 A-coded connector, and its internal electronics draw no more than 300 mA while the total load never exceeds 7.2 W. Network communication uses a shielded CAT.5 cable as the data medium and supports 100 Mbit/s full-duplex throughput on the EtherCAT segment. Physical connection to a ring or line topology is made with a 4-pin M12 D-coded receptacle that retains sealing when coupled. For input sensing, the device tolerates up to 100 mA AC/DC, allowing proximity switches to connect through the same housing. The gasketed enclosure meets the IP65 protection class, so it can be bolted to moving gantries without additional covers.

Safety circuitry is implemented through an integrated contact block that provides 1 NO / 2 NC channels for an emergency-stop pushbutton. These contacts may be switched between 5 V AC/DC and 35 V AC/DC, accommodating both logic-level and power-level stop chains. Signal presence is detected once at least 1 mA AC/DC flows, while protective components limit the breaking action to a maximum of 250 mW. This arrangement supports direct connection to stop circuits, contact inputs, and related control signals.