Physical Access Control System (PACS)
The complete electronic system that manages credentials, readers, controllers, locks, door status, and access events.
What is Physical Access Control System (PACS)?
A physical access control system, or PACS, is the complete system used to decide who may enter a controlled opening and when. It includes credentials, readers, controllers, power supplies, locking hardware interfaces, request-to-exit devices, door-position monitoring, management software, and the network connecting those pieces. Cloud-managed platforms may move the application layer off site, but field devices and life-safety interfaces still require coordinated installation. A PACS scope must be coordinated door by door. The access-control contractor, Division 8 hardware supplier, electrician, fire alarm contractor, and GC each may own different components. The sequence of operations should state what happens on valid access, forced entry, door held open, fire alarm, power loss, and emergency egress. Pricing depends on opening type, lock and power requirements, pathway, head-end capacity, software licensing, credentials, integrations, and commissioning—not simply the number of readers.
Frequently asked questions
Published references
Use the current project documents and adopted code. These links identify the standards owner, regulator, or manufacturer behind this article.
Where EIG PRO uses this
Related terms
Access Control
Electronic systems that grant or deny entry to doors, gates, elevators, and amenity spaces.
Mag Lock vs Electric Strike
Two methods of electrically controlling a door: a magnet that holds the door closed, vs a strike that releases the latch.
OSDP (Open Supervised Device Protocol)
A modern, encrypted communication standard for access control readers and controllers.
REX (Request to Exit)
A device — typically a motion sensor or push button — that signals the access control system to allow free egress.
Wiegand Protocol
A legacy one-way communication standard between access control readers and controllers, now largely superseded by OSDP.