NXT-4x4 Documentation

The NXT-4X4 Input/Output Expansion Module provides functionality to any Doors NetXtreme access control system by adding auxiliary I/O that can be used for additional access control functionality, monitoring non-reader doors or other devices, and creating powerful action sequences by linking input triggers to outputs. The module can be connected anywhere along the RS-485 trunk, most commonly at the controller or near a reader. One module can be added per trunk, allowing up to an extra 8 inputs and 8 outputs on an NXT-2D Controller and an extra 16 inputs and outputs on an NXT-4D controller.

The module's relays are re-assignable and interchangeable with the main controller's relays. The module can be mounted next to the door providing local door control and local door alarm functions while minimizing the cable bundle from door to controller. The unit also has a port to plug in a reader interface module (NXT-RMX) to allow Keri MS reader signals to be sent down the RS-485 line.


  • 4 auxiliary Inputs and 4 auxiliary Outputs per module
  • Up to 4 modules (16 Inputs and Outputs) can be added per NXT-4D, up to 2 modules (8 Inputs and Outputs) per NXT-2D
  • Re-assignable/Interchangeable with controller's door I/O
  • 4-State Supervision on Inputs
  • Can be used for Door Forced and Door Held Open Alarms as well as Auxiliary REX Inputs,

    Latch Integrity, Bond Sensor or other general purpose functions

  • Flash Memory for easy upgrades
  • Powered from Controller
  • Status Indicator LEDs for power, communication, and relay position
  • Dedicated Tamper Input
  • Quick Disconnect Connectors
  • Locking Metal Enclosure (optional without)

Please note, NXT is not compatible with the Doors/PXL family of products.


NXT-4x4 Documentation

Keri's Knowledge Base
Keri's YouTube Channel