Proximity readers
A proximity reader is an RFID reader mounted at an access point — a door, gate, or turnstile — that reads a card or key fob presented by the user and signals the connected locking hardware to release if the credential is authorised. Unlike a keypad encoder, there is no PIN to enter: the user simply holds their card or fob close to the reader face and the door opens.
HDWR proximity readers are designed specifically for door-control applications. They differ from the general-purpose RFID readers used for time-attendance and identification in that they output a Wiegand signal (rather than USB-HID keyboard emulation), making them natively compatible with access control panels and controllers.
Supported credential types
| Credential | Frequency | Standard | Notes |
|---|---|---|---|
| Proximity card | 125 kHz | EM4100 / Unique | Most common legacy credential |
| Key fob | 125 kHz | EM4100 / Unique | Pocket-sized equivalent of the card |
| Smart card | 13.56 MHz | MIFARE Classic, MIFARE Plus | Supports encrypted sectors; higher security |
| Smart card | 13.56 MHz | ISO 14443, ISO 15693 | Broad compatibility standard |
| NFC-capable phone | 13.56 MHz | NFC / ISO 14443 | Smartphone acts as credential where supported |
| Dual-frequency card | 125 kHz + 13.56 MHz | Both | Works with mixed-credential environments |
Output interface: Wiegand
HDWR proximity readers for access control output credentials using the Wiegand protocol over two open-collector data lines (DATA0 and DATA1). The two most common formats are:
- Wiegand 26 — 26 bits total: 1 parity bit + 8-bit facility code + 16-bit card number + 1 parity bit. Supports up to 255 facility codes and up to 65,535 card numbers per facility.
- Wiegand 34 — 34 bits total: expands the card-number field to 24 bits, supporting over 16 million card numbers. Required for large installations where 16-bit card numbers are insufficient.
The reader's Wiegand format must match the format expected by your access control panel or controller.
Relation to general RFID readers
Proximity readers (this category) and RFID readers use the same underlying radio technology but serve different roles:
- Proximity readers output Wiegand, are designed to be wired to a door controller, and typically mount flush to a wall using a standard electrical back-box.
- RFID readers output USB-HID (keyboard emulation), connect to a PC or time recorder via USB, and are used for identification, time-attendance, and software integration.
If your goal is to open a door, use a proximity reader. If your goal is to log a tag ID into software on a PC or time clock, use an RFID reader.
Installation notes
- Mount the reader on the unsecured (outside) face of the door at a comfortable height (typically 90–120 cm from the floor).
- Keep the reader at least 20 cm away from metal surfaces and other readers — metal backing reduces read range and adjacent readers can interfere with each other.
- Use shielded cable for Wiegand runs longer than 5 m; keep the run under 150 m.
- Power the reader from the same 12 V DC power supply as the electric strike where possible — this simplifies the installation and ensures that both devices go offline at the same time during a power event.
Proximity readers FAQ
What is a proximity reader and how is it different from a keypad encoder?
A proximity reader authenticates a user by detecting the RF field signature of a card or key fob held near the reader face — no keystrokes are involved. A keypad encoder requires the user to type a PIN code (and, on combined models, may also read a card). Proximity readers are faster to use, require no memorised secret, and are harder to shoulder-surf. Keypad encoders work when a user has forgotten or lost their card. In practice, many installations use combined keypad + RFID units that support both methods.
What is the read range of a proximity reader?
125 kHz proximity readers typically read cards at 5–15 cm and key fobs at 3–10 cm. 13.56 MHz readers have a similar or slightly shorter range under normal conditions. The actual range depends on the reader's antenna size, the card/fob antenna size, and nearby metal or RF interference. Thick metal doors, metal-clad back-boxes, and nearby power cables all reduce range. Test the reader in its intended mounting position before finalising the installation.
Which frequency should I choose — 125 kHz or 13.56 MHz?
Choose the frequency that matches the cards or fobs already in use at your site. If you are starting a new installation: 125 kHz (EM4100) cards are cheaper and very widely available, making them a good choice for cost-sensitive environments. 13.56 MHz (MIFARE) cards support encrypted data sectors, making them harder to clone and preferable for higher-security applications. Dual-frequency readers support both and are useful when migrating from a legacy 125 kHz system to 13.56 MHz without replacing all cards at once.
What is the Wiegand interface and why do proximity readers use it?
Wiegand is a simple, robust two-wire signalling protocol (DATA0 and DATA1) that has been the standard interface between access control readers and control panels for decades. When a card is presented, the reader sends the credential as a series of low pulses on the DATA0 and DATA1 lines — a '0' bit is a pulse on DATA0, a '1' bit is a pulse on DATA1. Because almost every access control panel and controller supports Wiegand, using it ensures that an HDWR reader is compatible with virtually any panel on the market. The two common formats are Wiegand 26 (supports up to 65,535 card numbers per facility) and Wiegand 34 (supports over 16 million card numbers).
Can I use a smartphone or NFC-enabled card to open a door?
Yes, provided the proximity reader supports 13.56 MHz and your access control software or panel supports NFC credential enrolment. Modern smartphones with NFC can emulate MIFARE Classic / ISO 14443 credentials using host-card emulation (HCE). However, not all access control panels support HCE-based credentials, and the level of security depends heavily on the panel software. For straightforward smartphone-based access, check whether the panel manufacturer explicitly supports NFC phone credentials before purchasing.
How do I enrol a new card or fob into the access control system?
Enrolment is handled by the access control panel or controller — not by the proximity reader itself. The reader's only job is to read and forward the credential to the panel; the panel stores the list of authorised credentials and makes the access decision. Enrolment procedures vary by panel manufacturer: typically you enter an 'add user' mode on the panel (via software or keypad), present the new card to the reader, and the panel stores the card's Wiegand number. Refer to your panel's manual for the specific steps.
Can I clone proximity cards, and how do I prevent it?
125 kHz EM4100 cards contain a fixed, unencrypted identifier that can be copied with widely available low-cost devices. If card cloning is a concern, switch to 13.56 MHz MIFARE cards — particularly MIFARE Plus or DESFire — which support cryptographic sector authentication, making cloning significantly harder. You can also add a PIN requirement (using a combined reader/keypad) so that a cloned card alone is not enough to gain entry.
Does the proximity reader work with any access control panel?
Any HDWR proximity reader with Wiegand output will work with any panel that accepts the same Wiegand format (26-bit or 34-bit). Wiegand is an industry-standard interface, so compatibility is very broad. The only potential mismatch is the bit format: confirm that the reader's Wiegand format matches what the panel expects. Some panels auto-detect the format; others require manual configuration. If the panel expects a different format (for example Clock-and-Data or RS485 OSDP), you will need a reader that supports that interface instead.