How Door Access Control Systems Work — A Breakdown by MTSS Group

At MTSS Group, we design and install access control systems that offer security, flexibility, and accountability. Whether you're protecting a corporate office, industrial site, or restricted government facility, understanding how these systems operate can help you make the right decisions.

1. What Is a Door Access Control System?

A door access control system regulates who can enter a building or restricted area using electronic credentials like swipe cards, fobs, or mobile devices. Unlike traditional keys, these systems offer programmable permissions, audit trails, and integration with alarms and CCTV.

2. Card Readers – Wiring and Protocols (Wiegand vs. OSDP)

Card readers are the user interface for the system—installed next to doors, they read credentials and send signals to the controller.

• Wiegand Protocol: One of the most common standards, typically uses 4 core wires:

  • +12V – Positive power supply

  • GND – Ground/negative

  • D0 – Data 0 line

  • D1 – Data 1 line
    Wiegand is unidirectional and lacks encryption, which makes it vulnerable in higher-security environments.

• RS-485 OSDP Protocol: A modern and secure protocol using encrypted two-way communication. OSDP readers also generally use 4 wires:

  • +12V

  • GND

  • RS-485 A (or +)

  • RS-485 B (or -)
    OSDP allows for advanced features such as reader supervision, real-time diagnostics, and configuration over the network.

At MTSS Group, we prioritise OSDP for new systems, particularly when security and scalability are key concerns.

3. Electronic Lock Types and Wiring

Locks are the physical components that secure a door until access is granted. Common types include:

• Electric Strikes: Unlock the door when energized. Often used with swinging doors.

• Magnetic Locks (Maglocks): Hold the door shut using electromagnetism; they require continuous power to remain locked.

• Turnstiles & Speedgates: Control pedestrian flow and prevent tailgating, ideal for secure lobbies or staff entrances.

Wiring for locks is usually simpler than readers:

• +12V or 24V (depending on lock type)

• GND (negative)
  Some may include monitoring outputs (e.g., lock status sensors), but the basic operation usually requires just power.

The door controller sends a signal to energise or de-energise the lock based on access permissions, either momentarily or continuously, depending on the setup.

4. Door Access Controllers – The Logic Core

Door controllers are the intelligent units behind the scenes. These circuit boards:

• Interpret signals from card readers

• Decide if access is allowed

• Activate the correct lock relay

• Monitor door position sensors and alarms

• Log access events and system alerts

They are connected to a local or cloud-based server and are programmed using intuitive software interfaces, allowing system administrators to manage users, schedules, access levels, and integrations with CCTV, alarms, or intercom systems.

5. Platforms We Use

MTSS Group integrates world-class platforms depending on your site's size and complexity:

• Inner Range Integriti – Powerful, modular, and ideal for enterprise-level deployments.

• Inner Range Inception – A compact, all-in-one system for SMBs with web-based management and mobile app control.

• Genetec Synergis – A unified, IP-based access platform that seamlessly integrates with CCTV, intrusion, and analytics for total situational awareness.

Contact MTSS Group to learn how we can customise an access control system to meet your operational needs, security standards, and future expansion plans.