March 31, 2026 • 15 min read
Security hardware is the physical equipment that controls who can enter a building, a floor, or a room. It includes intelligent controllers, card readers, electronic locks, request-to-exit devices, expansion modules, and the wiring and network infrastructure that ties it all together.
This guide breaks down every major component of a modern access control system — what it does, how it connects, and what to look for when specifying or replacing hardware.
The intelligent controller is the most critical piece of hardware in any access control system. It stores credentials locally, processes access decisions at the edge, and communicates with your access control software platform. When a controller fails, the doors it manages stop working.
The Mercury MP1502 is the current-generation 2-door intelligent controller. It controls 2 doors directly and can expand to 64 doors via RS-485 downstream panels. It is compatible with over 40 access control software platforms, including Genetec Security Center, Avigilon Alta, Lenel OnGuard, Honeywell Pro-Watch, ACRE, and RS2 Technologies.
Axis Communications makes network door controllers with Genetec Synergis firmware pre-loaded at the factory. The Axis A1210-G is a 1-door controller, and the Axis A1610-G is a 2-door controller. Both run on PoE, eliminating the need for a separate power supply.
A reader interface module connects one or two card readers to your intelligent controller over RS-485. The Lenel LNL-1300-S3 is a single reader interface that adds one door to a Lenel ISC. Mercury's MR52 serves the same function in Mercury-based systems. These modules can be daisy-chained up to 4,000 feet from the controller.
The Mercury MR16IN adds 16 monitored inputs, and the Mercury MR16OUT adds 16 relay outputs. Both connect via RS-485 and appear as additional I/O points in your access control software. Up to 32 modules can be multi-dropped on a single RS-485 port.
There are three common communication protocols between a reader and a controller:
This is the single most consequential design decision in any access control system. It affects wiring cost, fault tolerance, scalability, and long-term maintenance.
Centralized: Controllers in a central equipment room with long cable runs to each door. Simpler maintenance but a single controller failure can take many doors offline.
Distributed: Controllers placed near the doors they manage (often PoE-powered). Shorter cable runs, smaller failure blast radius, but more network devices to manage.
Most real-world deployments use a hybrid: Mercury MP1502 panels in central closets for high-density floors, and Axis A1210-G or A1610-G controllers for remote or single-door locations.