Overview
In a traditional deployment of an access control system to a door, there is a door controller connected back to a network (non-IP) or building controller. (different manufacturers use different names for these devices). The door controller typically handles two card readers so it can handle one or two doors depending on whether one door is using a card reader for both entrance and exit. It controls essentially three devices, a door contact (which lets the system know if the door is open or closed), the door lock and a card reader. Above the door frame is a junction box with power that powers each of the devices. The power supply for the controller is typically providing DC power and is provided with a battery back-up.

In the IP-based systems there is a direct network connection to either the door controller or the card reader, with the network connection providing low-voltage power. If the network connection is to the door controller, POE powers the door contact, the lock and the card reader. The door controller is really a gateway at the edge of the IP network, converting the data and protocols from the door devices to an IP format. For example Cisco’s base entry into this market is a gateway door controller that can handle two doors. It has characteristics of typical door controllers such as the capability to buffer events or cache access credentials; features that address reliability and network performance issues.

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