QR Code + RFID Access Control Readers for Doors, Turnstiles and Elevators

The reader does not decide who gets in. It decodes the code and forwards the content; permissions, validity periods and visitor records live in the controller or the visitor system. A typical flow:

1. The visitor or booking system creates a credential for the guest and registers it in the access controller or turnstile software as a temporary card number.
2. The system encodes that number in a QR code and sends it to the guest's phone, or prints it on a pass.
3. At the door or turnstile, the guest holds the code 0–20 cm from the window, centered on the lens within the 45° reading angle. The reader decodes it in under 200 ms and confirms with the buzzer and green feedback light.
4. The reader sends the content over its wired output. The controller checks it against the registered number and releases the door, opens the gate or enables the permitted floors. Staff cards follow the same path.
5. When the visit ends, the visitor system removes or expires the number in the controller, so the code stops working.

Because the reader only forwards data, one wiring scheme serves staff and visitors. A static QR code can be copied or forwarded like any image, so give visitor codes a short validity in the visitor system rather than reusing one code per guest.

Free-text QR content, such as a URL or a booking reference, cannot pass through a Wiegand controller as a card number. Send it over RS232, RS485 or TTL to a host that parses it, or have the visitor system encode a card number instead.

RS485 is a differential link and handles longer cable runs than RS232, which is why turnstile and elevator boards often use it. Wiegand is one-way, from reader to controller. USB vs RS232 vs RS485 vs Wiegand compares the links, Wiegand 26 vs Wiegand 34 shows the bit layouts, and other serial-output models are grouped under RS232 and RS485 RFID readers.

• Power. Budget 8–12 V DC at 800 mA per reader. Check the controller's reader output rating before powering a QR reader from it, or fit a separate supply with a common ground.
• Wiegand. If a card or code reads but the controller logs the wrong number, check that D0 and D1 are not swapped and that both ends use the same Wiegand format. The Wiegand reader wiring guide covers grounding and cable faults.
• Mounting. Both readers are 86 × 86 mm for a standard 86 mm wall box. The Q420-M is 18 mm deep and sits slim on the wall surface. The Q430-M is 42 mm deep overall, so plan an 86 mm wall box or a turnstile cut-out for its rear terminal box.
• Turnstiles. Place the reader where people can hold a code 0–20 cm from the window, centered on the lens. The Q430-M terminal block suits turnstile cabinets and installers who terminate cable on site.
• Elevators. The reader sends the credential to the elevator access controller over RS485, RS232, TTL or Wiegand, and that controller decides which floors to enable. Confirm that 8–12 V DC at 800 mA is available at the reader position.
• Configuration. Both readers are set up by scanning setting codes: the Q420-M for baud rate, card mode, Wiegand format and backlight; the Q430-M for baud rate and card mode (IC only for MIFARE, or IC + ID for MIFARE plus EM). The Q430-M has a pin-hole Reset button that restores the default settings.
• Environment. Both are rated -20 °C to +70 °C and 10–90 % RH. No IP rating is published for either model; state any enclosure requirement in your RFQ.

Choose the Q420-M for a slim reader on flying leads at doors and turnstiles wired to a Wiegand or RS485 controller. Choose the Q430-M when the same reader must also feed PC software over USB, when cable is terminated on site in a turnstile cabinet, or when you want to ask about a TCP/IP build.

State your controller's Wiegand format, the baud rate of your turnstile or elevator board and your card base in the RFQ, and the configuration is confirmed in your quotation. Integrators who resell under their own brand can review OEM and ODM options. To test with your own visitor codes and cards first, order a sample.