A HID controller (Edge EVO, v1000, v2000) is the main hardware. It's the brains of the hardware system. The controller stores data and makes access control decisions.

A HID panel (v100, v200, v300) is wired downstream of the controller to add functionality to the system. A v100 is a two door panel, v200 adds 16 inputs and a v300 adds 32 outputs.