XY-K485 TTL Serial Port to RS485 Converter Board Module

The XY-K485 TTL Serial Port to RS485 Converter Board Module is a compact industrial-style serial communication interface designed to convert TTL UART signals to RS485 differential signals and RS485 back to TTL. It is suitable for Arduino, ESP32, STM32, AVR, PLC, industrial controllers, sensors, meters and other embedded systems that need reliable RS485 communication.

The module supports 3.3V and 5V TTL logic, while its power input is designed for a wide 3.0V to 30V DC range according to commonly documented XY-K485 variants. It also provides automatic RS485 transmit/receive direction control, so the host microcontroller does not need a separate DE/RE direction-control pin.

Its PCB includes TXD and RXD status indicators, bidirectional TVS transient suppression, thermal recovery fuse protection and RS485 lightning protection circuitry, making it useful for projects where improved noise and transient protection is desirable.

Important: XY-K485 modules are sold by different manufacturers with slightly different specifications. Verify the exact module version before publishing guaranteed values such as maximum transmission distance, operating temperature or baud rate.

Product Highlights

• Model: XY-K485
• Function: TTL UART ↔ RS485 conversion
• Communication: RS485 half-duplex
• TTL compatibility: 3.3V / 5V
• Power input: 3.0V to 30V DC on commonly documented variants
• Automatic direction control: Yes
• TTL interface: VCC, TXD, RXD, GND
• RS485 interface: A+, B-, Earth
• TXD/RXD indicators: Yes
• Protection: Bidirectional TVS transient suppression
• Fuse: Thermal recovery/resettable fuse
• RS485 protection: Lightning/transient protection design
• Matching resistor: 120Ω provision on variants with R0 pads
• PCB size: Approximately 52 × 23 mm
• TTL connector: 2.54 mm-style connector
• RS485 connector: Screw terminal
• Typical applications: Arduino, ESP32, STM32, PLC, sensors, meters, automation and industrial communication

Documented XY-K485 variants commonly specify 110 to 256000 bps, support for at least 40 RS485 nodes, and operation around −40°C to +85°C; these values should be treated as variant-specific rather than universal to every XY-K485 board.

Specifications:

*Specifications can vary between manufacturers and board revisions.

XY-K485 Pinout

TTL Side

RS485 Side

The documented wiring uses the MCU's TXD → module RXD and module TXD → MCU RXD connections. The RS485 bus connects through A+ and B−.