Q420-M QR code + RFID access reader, angled front view with blue backlit label, scan lens and card area

Q420-M QR Code + RFID Access Reader, Wiegand 26/34, RS485, Slim 86-Box

Q: Can the Q420-M read QR codes from a phone screen?

Yes. It reads QR and 1D/2D codes printed on paper or shown on a phone screen, at 0–20 cm and a 45° reading angle centered on the lens. Scanning starts automatically and takes under 200 ms.

Q: What QR content works over Wiegand?

For Wiegand output the QR content must be a hex card-number string, because the controller only stores card numbers. Have your visitor system generate the number, register it in the controller, then encode it in the QR code. For other QR content, use a serial output (RS232, RS485 or TTL) to a host that parses it.

Q: Can the Q420-M connect to a PC over USB?

USB is not one of its listed outputs: the Q420-M provides Wiegand 26/34, RS232, RS485 and TTL. A PC can take its RS232 output on a serial port. If the reader must type into PC software over USB, choose the Q430-M, which has mini-USB keyboard and virtual COM modes.

Q: What power supply does the Q420-M need?

8–12 V DC rated for 800 mA per reader. Check the controller's reader output rating before powering the Q420-M from it, or use a separate supply with a common ground.

Q: Which RFID cards does it read?

125 kHz EM cards and 13.56 MHz MIFARE cards at 3–6 cm. The reader sends the card number and does not write to cards; the card-reading mode is selected by scanning a setting code.

The Q420-M is an 18 mm slim 86-box wall reader for visitor and staff access. It reads QR and 1D/2D codes, including codes on a phone screen, plus EM and MIFARE cards, and passes them to an access controller or turnstile board. QR range is 0–20 cm, card range 3–6 cm, with Wiegand 26/34, RS232, RS485 and TTL outputs.

Frequency: 125 kHz / 13.56 MHz
Cards / tags: EM cards, MIFARE cards (card number read)
Interface: Wiegand 26/34, RS232, RS485, TTL
Read range: 3–6 cm

Request a quote for Q420-M Order a sample Datasheet (PDF)

✓ Sample units for evaluation
✓ Output format confirmed for your software
✓ Private label & OEM options
✓ Reply within 1 business day

Why integrators choose the Q420-M

QR codes and cards in one reader — reads QR and 1D/2D codes, printed or on a phone screen, plus 125 kHz EM and 13.56 MHz MIFARE cards.
Four output types — Wiegand 26/34 for access controllers; RS232, RS485 or TTL serial for turnstile, elevator and host boards.
Slim 86-box format — 86 × 86 × 18 mm with a zinc-alloy frame and acrylic face, sized for a standard 86 mm wall box.
Configured by scanning — baud rate (9600, 19200 or 115200), card mode, Wiegand format and backlight are set by scanning setting codes.
Automatic sensing — scanning starts when a code is presented; decoding takes under 200 ms, confirmed by buzzer and green feedback light.

Sending visitor QR codes to a Wiegand controller

An access controller stores card numbers, not text, so a QR code has to look like a card to it. For Wiegand output, the Q420-M expects the QR content to be a hex card-number string. Your visitor or booking system generates that number, registers it in the controller as a temporary credential, and encodes it in the QR code sent to the guest's phone.

When the guest shows the code, the reader decodes it in under 200 ms and sends it in the Wiegand 26 or 34 frame chosen by setting code. Staff cards on 125 kHz EM or 13.56 MHz MIFARE use the same output, so one controller input handles visitors and staff.

If the host is a turnstile board, elevator controller or PC rather than a Wiegand panel, use RS232, RS485 or TTL at 9600, 19200 or 115200 baud. See USB vs RS232 vs RS485 vs Wiegand to pick the link.

Q420-M wiring and power

Wire	Signal
Red	+12 V DC
Black	GND
Green	Wiegand D0
White	Wiegand D1
Brown	RS485 A
Orange	RS485 B
Blue	RS232 RX
Yellow	RS232 TX

The table covers power, Wiegand, RS485 and RS232; TTL pin assignment is confirmed with your order. Size the supply for 800 mA at 8–12 V DC per reader, compared with 0–100 mA for the L410-W card reader. Check the controller's reader output rating before powering the Q420-M from it, or fit a separate supply with a shared ground.

Q420-M or Q430-M?

Choose the Q420-M when the reader should stay slim on the wall surface: it is 18 mm deep, with a zinc-alloy frame and flying leads. The Q430-M is 42 mm deep, terminates on a rear terminal block and adds mini-USB output for PC software. Both read QR codes at 0–20 cm and EM or MIFARE cards at 3–6 cm. Other serial-output models are listed under RS232 and RS485 RFID readers.

Q420-M specifications

General
Model	Q420-M
Type	QR code + RFID access control reader
Form factor	Slim 86-box wall mount
Housing	Zinc-alloy frame, acrylic panel
Color	Black panel, silver frame

Cards & reading
Card frequency	125 kHz / 13.56 MHz
Card standards	EM4100; ISO/IEC 14443A (MIFARE)
Supported cards	EM cards, MIFARE cards (card number read)
Codes	QR codes and 1D/2D barcodes, including codes on a phone screen
Barcode decoding	Image decoding
Card read range	3–6 cm
QR code read distance	0–20 cm
Reading angle	45°, centered on the lens
Read speed	< 200 ms
Scan trigger	Automatic sensing, buzzer prompt

Interface & output
Interfaces	Wiegand 26/34, RS232, RS485, TTL
Serial baud rate	9600 / 19200 / 115200 (set by setting code)
Configuration	Scan setting codes: baud rate, card mode, Wiegand format, backlight
Host OS (serial)	Windows XP / 7 / 8 / 10, Linux
Wiring	Red: 12 V; Black: GND; Green: D0; White: D1; Brown: RS485 A; Orange: RS485 B; Blue: RS232 RX; Yellow: RS232 TX
Indicators	Blue work light, green feedback light

Physical & environment
Power supply	8–12 V DC, 800 mA
Dimensions	86 × 86 × 18 mm
Weight	150 g
Operating temperature	-20 °C to +70 °C
Humidity	10–90 % RH

Specifications of Q420-M as supplied for the standard version. Read range depends on the card or tag, mounting surface and environment — we can test your own cards before you order.

Download the Q420-M datasheet (PDF, A4)

Card, tag and system compatibility

Works with

✓125 kHz EM (EM4100) cards
✓13.56 MHz MIFARE (ISO/IEC 14443A) cards, card number read
✓QR codes and 1D/2D barcodes, printed or shown on a phone screen
✓Access controllers with a Wiegand 26 or 34 input
✓Turnstile, elevator and host boards with RS232, RS485 or TTL serial; Windows XP/7/8/10 and Linux hosts

Not designed for

✕Writing or encoding cards (read-only)
✕USB output to a PC (not a listed interface) — the Q430-M adds mini-USB keyboard or virtual COM output
✕TCP/IP or Ethernet networking
✕Free-text QR content over Wiegand — use serial output, or issue QR codes that carry a hex card number

Card not listed? Send us the card type or a photo and we will confirm compatibility before you buy.

Integration in 4 steps

1
Fix the reader over a standard 86 mm wall box and wire an 8–12 V DC supply rated for 800 mA to red (12 V) and black (GND).
2
For an access controller, connect green to D0 and white to D1. For a serial host, connect brown and orange to RS485 A and B, or blue and yellow to RS232 RX and TX.
3
Scan the setting codes for Wiegand 26 or 34, the serial baud rate (9600, 19200 or 115200), card mode and backlight.
4
Test with a staff card and a visitor QR code. For Wiegand, the QR content must be a hex card-number string already registered in the controller.

OEM / ODM options for Q420-M

◆Wiegand 26 or Wiegand 34 output, selected by setting code; give your controller's format in the RFQ and we confirm the configuration in your quotation
◆Serial baud rate of 9600, 19200 or 115200 to match your turnstile or elevator board
◆Card-reading mode and panel backlight, both set by setting code
◆Choice of Wiegand, RS232, RS485 or TTL wiring on the same reader, so one part number covers door, turnstile and host projects

How OEM/ODM projects work →

Typical applications

Q420-M FAQ

Can the Q420-M read QR codes from a phone screen?