The AK-USB-RS485-FD-S is a USB to RS485/422 converter that has Full Duplex capabilities. Usually the RS485/422 protocol allows a single node of the network to either send or receive data, but not both at the same time. The AK-USB-RS485-FD-S board has two “channels”: one for receiving data and the other for transmitting data, achieving full duplex communication just like a traditional “serial port”.

The board is based on the SiLabs CP2102N chip and the RS485/422 channel is seen on the host as a virtual serial port. It comes in two versions: with screw terminals and without screw terminals to directly solder wires to the board (or to use another kind of connector). There is a drop menu up here to choose any of both options.

On the back of the board there is a solder jumper to enable/disable the 120 Ohm termination resistor independently on the “TX” and “RX” channels. The resistor is disabled by default but you can enable it by joining the jumper with some solder. On the top of the board there are two LEDs that blink when data is sent or received.

The board has a mini USB connector and it’s powered directly using the 5V from the USB bus.

We also have this same board but with an FTDI chip (instead of the CP2102N). You can find it here. If you are looking for a traditional, half-duplex, USB-to-RS485/422 converter we ship that too.


  • Full Duplex RS485/RS422
  • USB high speed
  • Based on the SiLabs CP2102N
  • Modbus compatible
  • 3Mbps max. data rate
  • Up to 32 transceivers in RS485 mode
  • Up to 32 transceivers in RS422 mode
  • Selectable 120 ohm load resistor
  • Optional screw terminals
  • Libraries and drivers available for Windows, Linux and Mac.




Additional information

Weight N/A
Dimensions N/A
Screw terminals

Without Screw Terminals, With Screw Terminals



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AK-USB-RS485-FD-S – USB to full duplex RS485/422 converter

An USB to Full-Duplex RS485/422 converter, based on SiLabs CP2102N.


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