1. Fundamentals & System Architectures
Every access control system, from a 4-door clinic to a 2,000-door tower, does the same four things: identify the person (credential), decide (controller database and rules), act (release the lock) and report (door state back to the head-end). Where the decision is made is what separates a robust system from one that locks the building when the server reboots.
Click any block in the hierarchy
Each block shows what it does, where it lives on site, what cable feeds it and what typically goes wrong at handover.
Network loss test (do this at every SAT)
Pull the uplink and present cards. A properly designed system keeps granting from the controller's local database and buffers events.
Architecture comparison
| Item | 2-Tier | 3-Tier | Cloud-hosted |
|---|---|---|---|
| Where the grant decision is made | Intelligent door controller (local DB) | ACU holds DB, RSI/sub-controller is only an I/O and reader interface | Edge controller caches DB, cloud holds master |
| Typical bus | TCP/IP from controller to server | TCP/IP to ACU, RS-485 from ACU to RSIs | Encrypted outbound TLS from edge to cloud |
| Offline behaviour | Full: grants, APB local, buffers events | ACU offline: RSIs drop to degraded mode (facility code only or locked) | Edge keeps cached DB, schedule and events; changes wait for reconnection |
| Best fit | Mid-size commercial, hotels, retail | Large campuses, high-rise with many doors per riser | Multi-site retail, small offices, portfolio owners |
| Site snag I see most | Controllers all on one unmanaged switch with no UPS | RS-485 run without termination, RSI addresses duplicated | Customer IT blocks outbound ports, nobody owns the firewall rule |
Reader protocol: Wiegand vs OSDP v2.2
| Parameter | Wiegand 26 / 34 / 37-bit | OSDP v2.2 (IEC 60839-11-5) |
|---|---|---|
| Physical layer | D0 / D1 open collector, 5 V pulses | RS-485 half duplex, differential pair |
| Max distance | About 150 m (500 ft) with 18 AWG, less with 22 AWG | 1,200 m (4,000 ft) on twisted pair |
| Cores needed | 6 to 8 (D0, D1, +V, 0V, LED, buzzer, hold, shield) | 4 (A, B, +V, 0V) plus shield |
| Topology | Point to point, one reader per port | Multi-drop, up to 126 addresses per bus (practical 4 to 8 readers per port) |
| Direction | One way, reader to panel | Bidirectional: panel polls, reader reports, LED/buzzer/text commands |
| Security | Clear text, card number can be sniffed and replayed with a cheap tap | Secure Channel AES-128, session keys, MAC per message |
| Tamper / supervision | None. Cut wires look like an idle reader | Reader is polled; offline or tamper alarms within seconds |
| Consultant position | Accept only for retrofit or low-risk internal doors | Specify as default for all new readers, Secure Channel enabled at SAT |
Wiegand frame builder (see why Wiegand is weak)
2. Credential Technologies & Mobile Access
The credential is the weakest link on most projects I review. Specs say "smart card" and the contractor supplies MIFARE Classic because the old card printer supports it. Name the technology, the key management and the reader configuration in the spec, then check the sample card at submittal stage.
Card technologies
| Technology | Frequency | Security | Clone risk | Notes for submittal review |
|---|---|---|---|---|
| 125 kHz Proximity (HID Prox, EM4100) | 125 kHz LF | None. Fixed ID broadcast | High: cloned in seconds with a handheld copier | Reject on new projects. Allow only as dual-tech card during migration. |
| MIFARE Classic 1K/4K | 13.56 MHz HF | Crypto1 (broken since 2008) | High: keys recovered offline | Reading UID only is worse than prox. Not acceptable for secure doors. |
| MIFARE DESFire EV1 | 13.56 MHz | AES-128 / 3DES, mutual auth | Low if diversified keys used | Fine for most commercial work. Confirm the reader reads the secure file, not the UID. |
| MIFARE DESFire EV2 / EV3 | 13.56 MHz | AES-128, proximity check, transaction MAC | Very low | Preferred for new builds. EV3 adds secure dynamic messaging. Multi-application (canteen, lockers, printing). |
| HID iCLASS (legacy) | 13.56 MHz | Global master key, compromised | High | Treat like prox. Migrate to iCLASS SE or Seos. |
| HID iCLASS SE / Seos | 13.56 MHz | SIO data object, AES-128, Seos secure messaging | Very low | Check if the project uses HID elite keys (site-specific) or standard keys. Elite is recommended for high-security clients. |
Mobile credentials
BLE (Bluetooth Low Energy)
Phone talks to reader over BLE. Read range adjustable from about 10 cm (tap mode) to several metres (hands-free / gesture "twist and go"). Good for car park barriers and accessible doors.
Watch for: reader range set too long, so a person walking past opens the door. Set range per door at commissioning and record it.
NFC
Phone emulates a card (HCE) or uses the secure element. Range 0 to 5 cm, same user habit as a card. Works with phone locked on most platforms (express mode).
Watch for: reader firmware must support the mobile credential applet, older 13.56 MHz readers do not.
Wallet provisioning
Employee badge in Apple Wallet or Google Wallet. Provisioned from the access control or identity platform, revoked remotely. Usually works for a few hours after the phone battery dies (power reserve).
Watch for: licence model per user per year. Put it in the tender BOQ, not as an afterthought.
Biometrics
| Modality | How it reads | Typical vendor FAR / FRR | Spoof prevention | Field reality |
|---|---|---|---|---|
| Optical fingerprint | Light image of ridges via prism | FAR ~0.001% / FRR 1 to 3% | Limited, fooled by good latent copies | Struggles with construction workers, dry or worn fingers, dust and outdoor sun |
| Capacitive fingerprint | Measures charge difference ridge / valley | FAR ~0.001% / FRR 1 to 2% | Better, needs live conductive finger | Wet hands and ESD sensitive. Keep indoors. |
| Multispectral fingerprint | Surface and sub-surface imaging | FAR ~0.0001% / FRR <1% | Liveness built in | Best fingerprint option for GCC labour camps and plant rooms |
| 3D face (NIR + visible) | Depth map plus IR texture | FAR 1 in 1,000,000 / FRR <1% | Rejects photos, screens, most masks | Fast, touchless, handles glasses. Check backlight at glazed lobbies. |
| Iris | NIR image of iris pattern | FAR 1 in 1,000,000+ / FRR ~1% | Strong with liveness | Data centres and vaults. Slower enrolment, user positioning matters. |
| Palm vein | NIR absorption by venous blood | FAR 0.00008% / FRR 0.01% | Very strong (internal feature) | Hygienic, contactless models available. Higher cost per reader. |
FAR / FRR threshold trade-off
Move the match threshold. Raising it lets fewer impostors in (FAR down) but rejects more genuine users (FRR up). The crossing point is the Equal Error Rate.
3. Complete Door Hardware & Locking Mechanics
Pick a device. You get the holding force, the fail mode, real current figures at 12 V and 24 V, and the mounting details I check on site. Most lock failures I see are not the lock, they are alignment, the wrong bracket, or the door closer fighting the lock.
Holding force vs side load
Maglock ratings are tested pulling straight off the magnet face. In real life the door is pushed at the lever position, with leverage about the hinges. Use this to see what a person at the handle can actually do.
Mounting accessory selector
4. Door Auxiliary Devices (DPS, REX, Break-Glass)
The lock gets all the attention in design reviews, but the small devices decide whether the door is safe and whether the head-end knows what is going on. A door with no DPS cannot report forced or held open. A maglock with no hardwired break-glass is a Civil Defence failure.
Door Position Switch (DPS)
- Surface magnetic contact: retrofit, visible, cheap. Gap rating 15 to 25 mm.
- Heavy-duty surface contact: armoured lead, roller shutters and loading bays, gap up to 75 mm.
- Flush recessed contact: drilled into frame head, preferred for new builds, tamper resistant.
- Roller / plunger switch: mechanical, for doors where magnet alignment drifts.
- High-security balanced contact: multiple reed switches balanced against a bias magnet, defeats external magnet attack. Needed for Grade 3 / 4 areas.
Request-to-Exit (REX)
- PIR REX (curtain pattern): mounted above the door on the secure side, aimed down the door face. Shunts DPS so exiting does not trigger forced door.
- Touchless optical button: IR proximity, hygienic, common in healthcare and offices.
- Mechanical push button: green "Push to Exit", with timer module or controller timing. For maglocks it must break lock power directly as well as signal.
- Lever / handle switch: microswitch in mortise lock, best REX for strike-locked doors because egress is always mechanical.
Emergency Break Glass (EBG)
- Green resettable call point, "Emergency Door Release".
- Double pole changeover: Pole 1 is in series with lock power and cuts it directly. Pole 2 signals the controller input so the event is logged.
- Signal-only EBG relies on the controller to release. If the controller has crashed or the cable is cut, the door stays locked. Not acceptable on any egress door.
- Mount 1.0 to 1.2 m AFFL on the egress side, within reach of the door. Confirm the exact height with the local authority drawing review.
Egress test bench
Set up the door the way the contractor wired it, then try to get out. This is the test the Civil Defence inspector does.
5. Interactive 2D Single-Door Cable Diagram
A typical secure single door: OSDP reader outside, maglock on header, DPS in frame, PIR REX and exit button inside, green break glass in series with lock power, all landed on a 2-door intelligent controller with a separate 12 V DC lock PSU that drops on fire alarm. Click any device or terminal for the terminal designation, cable type and the faults I usually find.
Select a device
Every node is clickable.
Fault injection
Cable schedule for this door
6. Multi-Door & Riser Topology Visualizer
Size the controllers floor by floor and see the riser. RS-485 buses need a 120 Ohm resistor at each physical end only, a daisy chain (never a star), and should stay within 1,200 m and 32 unit loads. IP edge controllers on PoE+ remove the RS-485 problem but move the risk to the network switch and its UPS.
7. Interactive Anti-Passback (APB) Simulator
Anti-passback stops one card being handed back through the fence to let a second person in. It only works if every way in and out of the area has a reader, which is why it is a design decision, not a software tick box. Pick a mode, pick a person and present their card at a reader.
8. Mantrap / Airlock Interlocking Simulator
A mantrap only lets one door be unlocked or open at a time. The interlock is decided on door position (DPS) and lock sense, not just on "the other door is not unlocked". Try the faults: a jammed DPS should make the interlock refuse, not guess.
9. High-Rise Elevator Access Control (Low-Level vs HLI)
Lift access control limits which floors a card can select. Two ways to do it: low-level, where a relay per floor per car sits in series with each COP button through the travelling cable, or high-level interface (HLI), where the access server talks to the lift group controller or destination dispatch system over a software API. Either way, fire service and recall must override access control every time.
Low-level vs high-level: what to write in the spec
| Item | Low-level relay interface | High-level interface (HLI) |
|---|---|---|
| Hardware | Relay boards in each car or machine room, one dry contact per floor per car, in series with COP button common | Gateway or server-to-server link, no relays at the COP |
| Travelling cable | Needs spare cores per car (reader data, power, and relay commons if relays are in the controller room). Check spare cores before awarding. | Only the reader cable, or none if readers sit at lobby DCS terminals |
| Destination dispatch | Not practical. DCS has no floor buttons in the car. | Native. Card at the DCS terminal books allowed floors only. Lift vendor publishes the API (for example a JSON / REST or vendor SDK). |
| Fire recall | Lift controller fire input must bypass relays. Relays should be wired so that loss of power enables all buttons (fail-safe to free access) unless the client accepts otherwise. | Lift controller ignores access commands in fire mode. Confirm in the interface matrix. |
| Who owns the risk | ELV contractor, with lift vendor approval of the wiring interface | Lift vendor and ELV contractor jointly. Get the interface control document signed early, licences are often extra. |
10. Turnstiles, Speed Gates & Barrier Lane Calculator
Lane count is the number architects always get wrong because they size for population, not for the morning peak. Size for the busiest five minutes, use the gate's real throughput with your reader's processing time, then add the accessible wide lane on top.
| Type | Typical throughput (persons/min) | Security level | Lane width | Where it fits |
|---|---|---|---|---|
| Optical speed gate (glass swing) | 25 to 35 | Medium, tailgate detection by beam arrays | 600 mm standard, 900 to 1000 mm wide lane | Grade A office lobbies |
| Flap barrier (retractable) | 30 to 40 | Medium | 550 to 650 mm, 900 mm wide | Metro, universities, large offices |
| Tripod turnstile | 20 to 30 | Low to medium, easy to climb | 500 mm | Labour camps, factories, stadium outer gates |
| Full-height turnstile | 12 to 20 | High, one person per rotation | Single or double rotor | Site perimeters, data centres, ports |
| Security revolving door / portal | 6 to 12 | Very high, weight or 3D sensing | Drum 1.6 to 2.4 m | Banks, data halls, government |
Lane calculator
11. Advanced Lock Power & Voltage Drop Calculator
Low voltage locks are less forgiving than people think. A 12 V maglock on a 60 m run of 0.5 mm² may only see 10 V, and holding force drops roughly with the square of voltage. Enter the devices on one cable run from the PSU and check what the far device actually gets.
Devices on this run
Conductor size comparison at this load
12. Power Supply (PSU) & Battery Standby Sizing
Size the lock PSU on continuous load plus inrush and spare, then the battery on the autonomy the spec or authority asks for. Remember the trick of access control: fail-safe maglocks draw current all day while locked, so they dominate standby. Fail-secure strikes draw only when released.
Loads on this PSU
13. Intrusion Detection Systems (IDS) Integration
Access control knows who opened a door. Intrusion detection knows someone is in a space that should be empty. On most GCC commercial projects the two are integrated so arming an area locks its doors, and a valid card at the area entry reader disarms it.
| Detector | Principle | Best use | Common false alarm source |
|---|---|---|---|
| PIR | Passive infrared, detects moving heat source across zones | Offices, corridors | AC diffuser blowing on it, sunlight on glazing, mounted above a heater |
| Dual-tech (PIR + microwave) | Both technologies must agree (AND logic) | Warehouses, plant rooms, hot spaces | Microwave range set too high, sees through drywall into corridor |
| Acoustic glass-break | Listens for flex frequency then shatter frequency | Shopfronts, ground floor glazing | Laminated glass not covered, heavy curtains blocking sound |
| Seismic / shock | Detects vibration of drilling or cutting | Vaults, ATM, safes, server cages | Mounted on wall with nearby plant vibration |
| Active IR beams | Beam interruption between transmitter and receiver | Perimeter, fence lines, roof access | Birds, fog, misalignment after wind, sand storms in the GCC |
| Door / window contact | Reed switch and magnet | Every perimeter opening | Poor alignment, loose doors in high wind |
Zone types
| Zone type | Behaviour |
|---|---|
| Entry / Exit | Starts entry delay when armed. Usually the main door contact. |
| Perimeter (instant) | Instant alarm when armed. Windows, fire exit doors. |
| Interior follower | Instant alarm when armed, but follows entry delay if the entry zone opened first (the path from the door to the keypad). |
| Interior (stay bypass) | Bypassed in Stay / Part arm so people can move inside. |
| 24-hour silent panic | Always active, never sounds locally, sends to ARC or control room. |
| 24-hour tamper | Always active, detector cover, cable cut, panel lid. |
Keypad and zone simulator
14. EOL / DEOL / TEOL Tamper Circuit Visualizer
End-of-line resistors let the panel tell the difference between a contact opening, a cable being cut and a cable being shorted. They only work if they are fitted at the device, not across the panel terminals. I fail this on site more often than any other intrusion item.
Truth table for this configuration
15. Fire Alarm System (FAS) Life-Safety Interlock
On fire alarm, every electrically locked door on an escape route must release. The release must be hardwired: a monitored FAIM relay that drops lock power (or the PSU fire input), not a software message to the access server. Software-only release fails the moment the network, server or controller is down, which is exactly what can happen in a fire.
Fail-safe vs fail-secure override matrix
| Door | Normal | Fire alarm | Power loss | Notes |
|---|---|---|---|---|
| Main lobby entrance (escape route) | Card / schedule | Released, free egress | Released | Maglock or EL panic. Hardwired FAIM release. |
| Stair door, office side | Card from stair side for re-entry | Released both sides | Released | Stair re-entry rules apply in high-rise. Mechanical egress always toward stair. |
| Fire rated door with strike | Card | Free egress by lever, latch stays engaged | Free egress by lever | Fail-secure strike so the door still latches for fire integrity. Egress is mechanical. |
| Server / data room | Card + PIN | Egress free, entry stays secured (client decision with AHJ) | Egress free by lever | Never lock someone inside. Exit side is always free. |
| Cash office / vault | Dual custody | Egress free, entry secured | Egress free | Fail-secure entry hardware, mechanical free egress. |
Code references for egress with electric locking
| Reference | What it asks for (summary, verify against current edition) |
|---|---|
| NFPA 101 - Sensor-release of electrical locking systems | Sensor on egress side releases the lock on approach. Loss of power releases. Manual release device within 1,525 mm (60 in) of the door, 1,015 to 1,220 mm (40 to 48 in) AFF, signed "PUSH TO EXIT", releasing independent of the electronics for at least 30 s. Fire alarm or sprinkler activation releases. |
| NFPA 101 - Delayed egress locking | Only where the occupancy allows. Releases after 15 s (30 s if the AHJ approves) of sustained push, irreversible process, local alarm, released on fire alarm and power loss, signage on the door. |
| BS 7273-4 | Categorises the actuation of door release mechanisms by risk (Category A, B, C). Defines how the fire alarm signal must reach the lock power, monitoring of the interface and fail-safe behaviour. |
| UAE Fire & Life Safety Code (Civil Defence) | Means of egress chapter: electrically locked doors on escape routes release on fire alarm and loss of power, with a manual release at the door. Confirm local DCD requirements at design NOC stage. |
| BS EN 13637 / BS EN 1125 / BS EN 179 | Electrically controlled exit systems, panic exit devices, emergency exit devices. The hardware on the door must be certified for the escape route type. |
16. Visitor Management & Barrier Automation
Visitors are where most access systems leak. A good flow pre-registers, verifies ID, issues a time-limited credential that only opens the host's floor, and expires it automatically. For vehicles, ANPR handles visitors and UHF tags handle regular staff at speed.
| Technology | Read range | Speed | Weakness | Use for |
|---|---|---|---|---|
| QR code (static) | Contact to 20 cm | 1 to 2 s | Screenshots shared, replayable | Events, low risk |
| QR code (dynamic, rotating) | Contact to 20 cm | 1 to 2 s | Needs app or wallet pass | Visitor and staff mobile access |
| ANPR camera | 3 to 15 m | 0.3 to 1 s per plate | Dirty or non-standard plates, glare, cloned plates | Visitors, deliveries, car park billing |
| UHF RFID windscreen tag (860 to 960 MHz) | Up to 10 m | Free flow | Metallised windscreens block it, needs a tag per car | Staff and residents, VIP lanes |
| Long-range BLE | Up to 10 m | 1 to 2 s | Phone must be on and app running | Residential car parks |
ANPR barrier simulator
17. Biometric & Multi-Factor Access Logic Builder
Assign a security level to each door and test it. Factors are something you have (card), something you know (PIN) and something you are (biometric). Dual custody adds a second authorised person inside a time window. Every factor you add costs throughput, so put the strong modes only where the risk justifies it.
Person 1
Person 2 (dual custody)
18. Interactive 2D Security Floor Map
A typical office floor with readers, door contacts, PIRs, window contacts, panic buttons and cameras. Run a scenario or click any device to trigger it. Watch the alarm stack the way a control room operator sees it, acknowledge, then clear. Linked cameras pop up automatically.
Alarm stack
19. 3D Hardware Inspection Viewer: Intelligent Door Controller Cabinet
Drag to rotate the enclosure, open the door and explode the backplate to see each component. This is the cabinet I open at every inspection: I check the PSU output setting, the battery date and voltage, the tamper switch, earth bonding of the door and the labelling of every field terminal.
Click a component
Every coloured block on the backplate is clickable.
Cabinet inspection points
| Check | Acceptance |
|---|---|
| PSU output voltage (no load and full load) | 13.6 to 13.8 V on 12 V systems, 27.2 to 27.6 V on 24 V systems |
| Battery | Date label within 4 years, terminal voltage above 12.6 V each block after charge, no swelling, correctly fused lead |
| Tamper switch | Opening the door raises a tamper alarm at the head-end within seconds |
| Fire alarm interface | FAIM relay or PSU fire input wired, monitored, labelled, tested with the FA contractor present |
| Earthing | Enclosure and door earth bonded, cable screens terminated at the panel end only |
| Labelling | Every field cable ferruled, terminal schedule taped inside the door, as-built matches |
20. 4D Operational & Time-Based Access Simulation
Time is the fourth dimension of an access system. Doors change state through the day on schedules, holidays override them and night lockdown closes everything. Press play and watch a full 24 hours. The "first person in" rule keeps the main entrance locked until a valid staff card has been used, so a snow day or a public holiday does not leave the lobby open to the street.
21. Testing & Commissioning (T&C) Master Dashboard
The 25-point SAT list I use for access control handover. Tick items as they are witnessed, add remarks for anything that fails, sign off at the bottom and export. Your ticks are saved in this browser.
Sign-off
22. Field Troubleshooting & Maintenance Guide
The faults that actually generate call-outs, in the order I would check them. Filter by symptom or keyword.
Planned preventive maintenance
| Frequency | Task |
|---|---|
| Monthly | Review head-end for offline devices, forced and held-open trends, battery trouble events. Remove leavers. |
| Quarterly | Walk test sample of doors: card, REX, DPS, EBG. Clean maglock faces. Check closers. |
| Six-monthly | PSU output and battery discharge test. Fire alarm release test with the FA contractor. |
| Annually | Full door audit, firmware review, database backup restore test, credential audit, penetration review of controller network. |
23. SIRA (Dubai), GCC Authority & International Codes
Security systems in the GCC are approved by the security authority as well as Civil Defence. Get the authority category for the building early, because it fixes camera counts, recording days, access control and intrusion requirements, and the approved contractor list. The table below is a working summary; always read the current edition issued by the authority.
24. Comprehensive Master Quiz
30 questions across the whole lab. Answer each one to see the explanation straight away. Your score updates as you go.