Product Image



Product Usage

U2D2 is a small size USB communication converter that enables to control and operate DYNAMIXEL with PC.


In case of unstable communication with U2D2, check if there is a reference voltage difference in the communication.
Please check PC and other devices are grounded properly.
Failing to do so might cause damages on the U2D2.









Convert USB and UART

3Pin TTL Level

Connect to the DYNAMIXEL with 3Pin TTL Level Communication.

4Pin RS-485

Connect to the DYNAMIXEL with 4Pin RS-485 Communication.

Status LED

Display status of Power supply, TxD(Data write) and RxD(Data Read).

Micro-B USB

Connect to the PC with USB cable


Communication Error

Reference BPS

Actual BPS






























Less than 3% of the baud rate error will not affect to the UART communication.


Supply Power

U2D2 does not supply power to DYNAMIXEL, therefore, an external power supply should provide power to DYNAMIXEL as below.

Before connecting DYNAMIXEL to an external power supply, please check the recommended voltage for DYNAMIXEL.


Caution for Power Supply

- For a stable power supply, it is recommended to use ROBOTIS controller or SMPS2Dynamixel.

- When connecting cable to DYNAMIXEL, please turn off the power.


[ Using SMPS2Dynamixel ]

In order to operate DYNAMIXEL with SMPS2Dynamixel, please connect DYNAMIXEL to SMPS2Dynamixel, then connect SMPS to SMPS2Dynamixel as shown below image.

Please compare operating voltage of DYNAMIXEL with 12V 5A ROBOTIS SMPS before supplying power.


[ Using ROBOTIS Controller ]

In order to operate DYNAMIXEL with OpenCM 485 Expansion board, please connect DYNAMIXEL to OpenCM485 Exp board, then connect battery or SMPS to the expansion board as shown below image.

Please compare operating voltage of DYNAMIXEL with battery or 12V 5A ROBOTIS SMPS before supplying power.

OpenCM485 EXP board will bypass the input power source to output power.


[ Using Power Supply ]

In order to operate DYNAMIXEL with Power Supply, please configure the power supply for the DYNAMIXEL before connecting cable.

Please check the pinout of the cable to avoid connecting to wrong pins.


Exchanging Communication Data

When data is transmitted from the USB port in PC to peripheral devices(Tx), all connected device will receive an identical data.

On the other hand, when data is received from one of the peripheral devices(Rx), it will be automatically converted as USB communication and sent to the PC. During this process, received data will not be transmitted to other peripheral devices. If data from more than two peripheral devices are received, the received data can be corrupted.

Therefore, when connecting 3Pin TTL Level DYNAMIXEL and 4Pin RS-485 DYNAMIXEL at the same time, all connected DYNAMIXEL should have its unique ID in order to prevent receiving corrupt data. In addition, when using Bulk Read and Sync Read instructions that requires to receive data from multiple DYNAMIXELs, relevant DYNAMIXELs should be connected to the same communication channel or else the instruction will not work properly.


  1. RoboPlus
    RoboPlus supports Windows environment to manage controllers and DYNAMIXELs.
    A. R+ Task 2.0 : R+ Task 2.0 can be used when downloading Task Code to the controller.
    B. R+ Motion 2.0 : R+ Motion 2.0 can be used when downloading Motion file to the controller.
    C. R+ Manager 2.0 : R+ Manager 2.0 is used to connect controllers or DYNAMIXELs and update firmware or test the control table..
    ROBOTIS homepage (http://www.robotis.com)
  2. Dynamixel Workbench
    Dynamixel Workbench supports Linux environment to test control table of DYNAMIXEL.
    ROBOTIS GitHub (https://github.com/ROBOTIS-GIT)
  3. Dynamixel SDK
    Dynamixel SDK supports various programming languages such as C, C++, C#, MATLAB, LabVIEW, Python and Java in order to help developing DYNAMIXEL control software. Dynamixel SDK provides a bundle of functions/methods that can be used for operating DYNAMIXEL with protocols in the form of digital packet. Dynamixel SDK is free to download from GitHub.
    ROBOTIS GitHub (https://github.com/ROBOTIS-GIT)

Additional Features

  1. Internal DIP Switch
    There is a two-pole switch inside of the plastic cover. This switch is set to OFF as a default. Under normal circumstances this default setting is recommended, therefore, the switch cannot be accessed without opening the case. Please open the case and set RS-485 termination resistor and UART 3.3V power switch only after thoroughly understand its usage   

    A. RS-485 Termination Resistor(120Ω) Switch
    Transmission devices are designed to have certain impedances based on design standard and signal reflection or interference can occur when impedance do not match over the transmission lines. The termination resistors at the end of transmission lines suppress such effect by adjusting impedance and allowing constant current flow. However, the termination resistor is not a mandatory, especially in a short RS-485 network with lower communication baud rate.
    If communication is suffering from frequent errors, the termination resistor might be required. The regular 120Ω termination resistor will be applied on the transmission line by shifting the switch to ON. If termination resistor doesn’t resolve the communication issue, the resistance value might need to be adjusted.

    B. UART 3.3V Power Supply Switch
    The peripheral device such as controllers that can be connected to the 4Pin UART usually have an external power source, therefore additional 3.3V power from the UART port #2 pin is not necessary.
    However, when connecting BT-410 that does not have an external power source needs to be powered by the 4Pin UART port #2 pin. In this case, the UART 3.3V power switch need to be turned on.
    If the switch is turned on, second pin of the 4Pin UART connector will be able to supply 3.3V.

  2. Caution for Assembly

    - Bolt for Mount Hole : M2 Tap bolt
    - Distance between two mount holes : 42mm
    - Mount Hole Depth : Valid depth 4.7mm, Depth from the surface 5.5mm