Door Monitoring for Access Control: Contacts, REX and Forced-Door Alarms

Reliable door monitoring is one of the most important parts of a well-designed access control system. Granting access is only half the job: the system also needs to know whether the door actually opened, whether it closed again, whether someone requested to exit, and whether the door was opened without a valid access event.

For New Zealand installers, the key building blocks are usually a door contact, a request-to-exit (REX) device, the locking hardware and the access controller. When these inputs are configured correctly, the controller can distinguish normal entry and exit activity from events such as a door being forced open or left open too long.

What does door monitoring do?

A monitored access-controlled door gives the controller feedback about the physical state of the door. Without that feedback, the controller may know that a credential was accepted and a lock output changed state, but it cannot confirm whether the door opened, whether it shut properly or whether somebody opened it by another means.

A typical monitored door uses several signals:

• Door contact: reports whether the door is physically open or closed.
• REX input: tells the controller that somebody is legitimately leaving through the door.
• Lock output: controls an electric strike, magnetic lock or other locking device.
• Credential event: records an authorised access request from a card, keypad, mobile credential, biometric reader or another approved method.

Used together, these signals allow the controller to make sense of what is happening at the opening instead of treating every door movement the same way.

Door contacts: the foundation of door-status monitoring

A magnetic reed contact is commonly used to tell the access control system whether a door is open or closed. The contact is normally fitted so that the switch changes state when the door moves away from the frame.

For a concealed installation, a recessed contact can provide a clean finish while still giving the controller the door-position feedback needed for event logic.

MS-03R recessed mount reed switch is one example of a recessed door contact suitable for monitoring the physical position of a door.

What is a request-to-exit input?

A request-to-exit input tells the access control system that an exit event is expected. This matters because many controlled doors allow free egress from the secure side. The person leaving may not present a credential, so the controller needs another signal to identify the door opening as authorised.

REX can be provided by several device types, including push buttons, touchless sensors and PIR motion detectors. The correct choice depends on the door, traffic flow, hygiene requirements, accessibility and the behaviour expected from users. For a detailed comparison, see our guide to push-button, PIR and touchless request-to-exit devices.

REX is not the same as an emergency door release. A REX input indicates that a normal exit is expected; the locking and emergency egress arrangements must still meet the applicable building, fire and accessibility requirements. Confirm whether the chosen controller treats REX as a monitoring event, a lock-release command or both, and test the configured behaviour on site.

Touchless REX devices

Touchless request-to-exit devices are useful where users should be able to trigger the exit input without pressing a mechanical button. They can work well in commercial environments with frequent traffic or where reducing physical contact is desirable.

The Trojan Prox-Rex is a touchless egress device designed for access control applications and can be used to provide a dedicated exit request signal.

PIR REX sensors

PIR request-to-exit sensors detect movement in the approach area and can automatically signal an exit request. They are often useful where hands-free egress is preferred, but installers should pay close attention to detection coverage and positioning so normal movement near the door does not create unwanted triggers.

The Risco iREX Plus is a PIR-based request-to-exit device that can be used where automatic movement detection is preferred.

How forced-door alarms work

A forced-door alarm is generated when the controller detects that the door has opened without the access sequence it expected. For example, if the door contact changes to the open state without a valid credential, approved REX event or other programmed release condition, the controller can treat that opening as abnormal.

The exact event logic depends on the access control platform and how the inputs and timers are programmed. A forced-door event should therefore be tested as part of commissioning rather than assumed to work simply because a door contact has been connected.

Door-held-open alarms

Door-held-open monitoring uses the door contact together with a programmed time period. After an authorised access or exit event, the system allows the door to remain open for a defined period. If the door stays open beyond that period, it can create a door-held-open event.

This is useful on doors where leaving the opening unsecured creates a security risk. The timer should be long enough for normal traffic and accessibility requirements while still identifying genuine exceptions.

Door event logic at a glance

The following table shows typical outcomes for a monitored access-controlled door. Actual alarm behaviour depends on the controller, programmed shunt periods, lock type and site-specific egress design.

Door event	Typical input sequence	Expected controller response
Authorised entry	Valid credential, release, door contact opens and closes	Record normal access and door activity
Authorised exit	Approved REX signal, followed by door contact opening and closing	Allow the programmed exit sequence without a forced-door alarm
Forced opening	Door contact opens without a recognised authorised entry, exit or release condition	Generate a forced-door event if configured
Door held open	Door remains open beyond the configured permitted interval	Generate a door-held-open event if configured
Contact or alignment fault	Door contact reports an unexpected or intermittent state	Investigate wiring, contact alignment and supervision settings

Commissioning note: Do not assume a REX signal automatically releases every lock. Verify the controller’s configured REX behaviour, the lock-release circuit and all independent emergency egress provisions.

Typical event sequence

A correctly configured door can be programmed around a simple sequence:

1. A valid credential is presented, or the REX input is activated.
2. The controller releases the locking hardware.
3. The door contact changes state when the door opens.
4. The system allows an authorised open period.
5. The door closes and the contact returns to its secure state.
6. If the door opens without the expected release event, or remains open too long, the controller creates the appropriate alarm or event.

This event relationship is why door contacts and REX inputs should be treated as part of the access-control design rather than optional accessories.

Installation points that matter

• Confirm the contact state: verify the controller clearly distinguishes door open and door closed.
• Check alignment: poor reed-switch or magnet alignment can cause intermittent door-status reporting.
• Position REX devices carefully: especially PIR devices, so the detection area matches the intended approach path.
• Test timing: confirm unlock time, door-held-open delay and re-lock behaviour under real traffic conditions.
• Test abnormal events: safely simulate an unauthorised opening, using the manufacturer’s commissioning procedure, and confirm the intended alarm event is generated without damaging door hardware.
• Review life-safety requirements: access control must not compromise required emergency egress or fire-door operation.

Door monitoring and access-control system design

Door monitoring becomes particularly valuable as a site grows. A controller that records meaningful door events can give installers and site managers a clearer audit trail than a system that only records credential transactions.

For multi-door commercial systems, this makes it easier to identify doors that are repeatedly left open, unusual openings outside normal access events, or locations where hardware and timing may need adjustment.

Planning a monitored access-controlled door? Browse the Essential Security Supplies access control range for controllers, door contacts, request-to-exit devices and associated door hardware. Check contact type, controller input compatibility and egress requirements before selecting equipment.

Technical references

Door-contact and REX behaviour varies by controller. For examples of the underlying event logic, see the manufacturer’s Kantech door-contact guidance and REX configuration guidance. Confirm actual wiring, alarm logic and egress settings against the documentation for the controller installed on site.

Door monitoring FAQ for installers

Do I need a door contact if the access controller already releases the lock?

Yes, if the project requires actual door-position monitoring. The lock output records the release command; a correctly installed door contact confirms whether the door physically opened or closed.

Can a PIR sensor cause unwanted request-to-exit events?

It can if its detection area covers nearby foot traffic or unintended movement. Confirm the mounting position and detection pattern, then test both expected exit movement and activity outside the intended approach path.

What is the difference between a forced-door and a door-held-open event?

A forced-door event generally means the contact detects an opening without the programmed authorised access or exit sequence. A door-held-open event means the door remains open longer than the permitted time, including after an otherwise authorised opening. The precise definitions depend on the controller configuration.

Which checks should be included in final commissioning?

Test authorised entry, normal exit, a safely simulated unauthorised opening, door-held-open timing, contact alignment and restoration to the secure state. Confirm alarms and event logs at the controller or management software. Independently verify that emergency egress and fire-door operation meet the relevant project requirements.

Key takeaway

A door contact tells the system what the door is doing. A REX device tells the system when an exit is expected. The access controller combines those signals with credential and lock events to determine whether the opening is normal, forced or held open too long.

For installers, the most important step is not simply fitting the devices but commissioning the event logic as a complete system. Test every normal and abnormal sequence at the door so the final event history accurately reflects what is happening in the real world.