page_title: Access control
section_title: Access control topology
hierarchical_section_title: Access control / Physical security / Access control topology
caption_attribution_description: English: Access control door wiring diagram
context_page_description: In the fields of physical security and information security, access control is the selective restriction of access to a place or other resource while access management describes the process. The act of accessing may mean consuming, entering, or using. Permission to access a resource is called authorization.
  Locks and login credentials are two analogous mechanisms of access control.
context_section_description: Access control decisions are made by comparing the credentials to an access control list. This look-up can be done by a host or server, by an access control panel, or by a reader. The development of access control systems has observed a steady push of the look-up out from a central host to the edge of the system, or the reader. The predominant topology circa 2009 is hub and spoke with a control panel as the hub, and the readers as the spokes. The look-up and control functions are by the control panel. The spokes communicate through a serial connection; usually RS-485. Some manufactures are pushing the decision making to the edge by placing a controller at the door. The controllers are IP enabled, and connect to a host and database using standard networks
caption: Typical access control door wiring
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