A commercial access control system decides who may open a door, when, and for how long, and it records every attempt. The working parts are the credential, the reader, the controller, the locking hardware and the power supply. Door hardware and power are where most systems quietly fail.
A mechanical key cannot tell you who used it. A card, fob or phone credential can, and it can be revoked from a desk in the time it takes to walk someone out of the building. That difference is the real reason a business moves from keys to access control, and it is also why a badly designed system creates more work than it removes.
We design from the doors outward: how each door is used, what it is made of, how people leave the building, and who needs to change permissions. Readers and software are chosen after that, not before.
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| Option | Reasonable fit | What to watch |
|---|---|---|
| 125 kHz proximity card | Interior doors where cards already exist | A fixed number that a handheld reader can copy |
| 13.56 MHz smart card | Main entrances and multi-tenant buildings | Reader and card must use the same secure format |
| Mobile credential | Staff who always carry a phone | Phone battery, app updates and visitor coverage |
| Keypad PIN | Low-traffic doors with no card issue | Shared codes and watching over a shoulder |
| Biometric | Cash rooms, pharmacies, records storage | Enrollment time and a higher cost per door |
What the system actually controls
The reader is the visible part. Behind it sits a controller that stores permissions for its doors, a lock the controller releases, and a power supply that keeps both running when utility power drops. Above those sits the management software where people are added, schedules are set and the event log is read.
A small site can run from a single door controller. A multi-building site distributes controllers so a network or server fault does not lock out a campus. In both cases the decision is made at the door, which keeps doors working during an outage.
- Credentials: proximity cards, fobs, mobile credentials or biometrics.
- Readers at each controlled door, inside and out where anti-passback matters.
- Controllers that hold permissions and keep working through a network fault.
- Locking hardware matched to the door type and the egress requirement.
Choosing credentials and reader technology
Credential technology decides how easily a lost card can be copied. Older 125 kHz proximity cards carry a fixed number that a handheld reader can clone. 13.56 MHz smart cards support mutual authentication and encrypted data, and mobile credentials move the decision onto a phone using Bluetooth or near-field communication.
Reader protocol matters as much as the credential. Wiegand is a one-way signal with no encryption and no way for the reader to report tampering. OSDP is bidirectional and encrypted, so the controller can tell whether a reader has been removed or swapped. Where the controller supports it, OSDP is the better long-term wiring decision.
- Smart cards and mobile credentials where duplication is a real risk.
- A keypad or biometrics as a second factor for server rooms, cash offices and pharmacies.
- Hands-free or long-range readers for parking gates and loading doors.
- Credential formats that will still be available when the current card stock runs out.
Door hardware decides whether it works
A system can be specified correctly and still fail at the door. An electric strike needs a frame that can be cut and a door that closes squarely. A maglock holds almost any door but fights egress. Electrified mortise hardware is the cleanest option on a hollow metal frame and the most expensive to install.
Every controlled door should have a door position switch so the system knows whether it actually closed, and a request-to-exit device so someone leaving does not have to badge out. Without those two inputs, held doors generate nuisance alarms and forced-door events go unnoticed.
- Strike, maglock or electrified hardware chosen per door, not per project.
- Door position switches and request-to-exit sensors on every controlled opening.
- Closers and coordinators adjusted before the lock is blamed for a jam.
- Weather-rated hardware and drip protection on exterior doors.
Free egress is a life safety function
No access decision may trap an occupant. On fail-safe hardware such as a maglock, removing power unlocks the door, so a fire alarm interface, a request-to-exit sensor and a manual release are part of the design rather than options. Fail-secure hardware stays locked without power, which suits a records room and is wrong for a main exit.
Delayed egress, door-held alarms and lockdown change how people leave a building. We write those behaviors down and walk them with the site before programming, because the authority having jurisdiction sets the requirement and the system has to meet it.
Power, cable and controller placement
Locks draw current in bursts, and voltage drop over a long cable run is the usual reason a strike buzzes instead of releasing. A dedicated access control power supply with battery backup, correctly sized cable and a separate circuit for lock power prevents most callbacks.
- Battery capacity sized for the lock load and the outage the site expects.
- Cable gauge checked against run length and current, not against habit.
- Controllers and power supplies in a locked, ventilated, accessible space.
- A documented process for adding a door, a person or a schedule change.
Working with an existing access control system
Many sites already have readers, controllers and credentials worth keeping. We audit what is installed door by door and test whether the existing credentials can move to a new system without reissuing every card.
Where the hardware is sound we extend it: add doors, replace failed locks, correct egress problems and bring reporting back into one place. Where it is not, we say so before quoting and separate what can be reused from what has to be replaced.
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Frequently asked questions
Can access control trigger our cameras?
Yes. A door event can pull live video or a recording clip into the access control screen, and a forced or held door can raise an alarm with the matching footage attached. The link is configured per door, so only the events that matter produce a pop-up.
What happens during a network outage?
Controllers keep their stored permissions and schedules, so doors continue to work from the last configuration they received. Management software and remote reporting stop until the network returns, and events are buffered on the controller where it supports that.
Do we have to replace our existing cards?
Often not. Cards can frequently be reused when their format is one the new readers support, which avoids reissuing every credential. We test a sample card and confirm the format before promising reuse.
Are mobile credentials as reliable as a card?
They depend on the phone battery, the reader and the app. Mobile is convenient for staff who always carry a phone and awkward for contractors or anyone who may not. Many sites run mobile credentials alongside cards rather than instead of them.