EJ9404 by Beckhoff

The EJ9404 is a power-distribution plug-in produced by Beckhoff within the EJ EtherCAT Plugins series. Designed to inject auxiliary power into the EtherCAT backplane on a machine-specific signal distribution board, the unit supplies additional power to connected electronic terminals. By stabilizing the voltage rail for downstream devices, the module supports reliable fieldbus communication and consistent sensor and actuator operation in distributed industrial automation cabinets.

The plug-in can deliver up to 12 A of continuous E-bus current, which is the maximum load it can share among connected I/O slices without overheating the copper planes. The internal regulator maintains the E-bus potential at 3.3 V, matching the logic level required by neighboring EtherCAT devices. This rail uses a single common ground as its reference point, simplifying board layout and noise management. The incoming supply must meet SELV/PELV requirements, allowing the module to operate from a safety extra-low-voltage or protective extra-low-voltage source without additional isolation hardware. Its assigned module function is an additional E-bus supply, so it reinforces the power rail rather than forwarding data between terminals.

The housing clips onto the designated signal distribution board section while maintaining the bus pitch and keying used by other EJ plug-ins. The device supports a standard mounting position, allowing vertical or horizontal installation without derating. A front-edge pin supports an optional reset line that momentarily disconnects the E-bus when triggered. This reset input can be used for brownout testing or controlled restart sequences during system setup and maintenance. The compact housing is 12 mm wide, allowing the module to fit into densely arranged signal distribution assemblies without requiring additional board space.