Full Duplex TTL to Half Duplex TTL Converter 질문


제가 직접 만든 제어기에 Dynamixel을 연결해서 제어하고자 하는데, 제어기의 output이 통상 사용하는 Full duplex TTL 이라서 Dynamixel을 제어하는데 어려움이 있는 상황입니다.

Dynamixel의 Half duplex ttl이 통상적인 uart 통신과는 달라서, 일반적인 Full Duplex TTL to Half Duplex TTL 컨버터를 로보티즈 혹은 기타 쇼핑몰에서 판매하고 있을 줄 알았는데, 비슷한 제품을 찾지 못했습니다.

제가 할 수 있는 방법은 홈페이지에서 안내한 대로 제가 직접 회로도를 납땜하여 구성하거나, 혹은 Full Duplex TTL을 RS485 로 바꾼후 RS485 to Dynamixel TTL 로 변환하는 모듈을 구매하여 사용하는 것 같은데, 둘 다 그리 좋은 방법은 아닌 것 같아 Full Duplex TTL 을 Half Duplex TTL로 바꾸는 일반적인 모듈을 판매하고 있지는 않으신지 여쭤봅니다.


Hello @gr3658 ,

Does your custom controller have a USB Port available to control Dynamixels? If it does, you can use the U2D2, as the easiest solution:

The ROBOTIS e-manual website does provide the circuitry for converting Full to Half Duplex here:

And I have tried to recreate this circuitry myself, but my soldering skill does not extend to Surface Mounted (SMT) devices (such as the 74LVC2G241) which are too small for me to handle. You can read my post below for a DIP solution.

If your controller is ARDUINO compatible, you also should be able to use the DXL MKR Shield with your custom controller if it has 3.3 V UART Port, please these two posts regarding the use of ESP32 and ESP32 S3 with the DXL MKR Shield:

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Thank you for your kind reply.

Actually, I considered what you suggested, USB port and Arduino Shield.

Unfortunately, My controller is not arduino compatible and doesn’t have USB port.

As you said, soldering the circuit myself is the last option and what I want to avoid.
But as your answer implies, it seems there are no appropirate product to convert full duplex to half duplex.

Thank you

Right now the only non-soldering option is to use the DXL MKR board with 3.3 v UART on your controller and straight DXL SDK software on your controller. Is your controller on Linux? The DXL MKR has its own power circuit for the Dynamixels so that can be handy

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시중에 RS422 to RS485 컨버터 제품을 판매하고 있습니다.

해당 제품을 찾아서 한번 이용해보시는 것도 좋아보입니다.

포털사이트(구글, 네이버 등)에 "RS422 to RS485"를 검색하시면 여러가지 제품이 나옵니다.


Well, my controller is running NuttX RTOS.
But without using library, I think I can control it by sending packet directly to the motor.

But One thing I am curious is that can I control multiple dynamixels at the same time with one tx/rx pin? I know I can designate the address of specific motor and control it, but I am not certain I can do it at the same time.

If I can do it, what is the time difference between each motor’s operation If I give operation to the multiple motor at the same time?

Thank you


제가 하려는 것은 일반 Full Duplex TTL UART 통신 → Dynamixel Half Duplex TTL 인데, 혹시 말씀하신 RS422 to RS485 컨버터는 어떻게 사용되는건지 알 수 있을까요? Dynamixel은 RS485가 아니라 3 pin TTL 통신 (Dynamixel T 모델) 을 사용합니다.

In theory, that is a possibility, but you need to study and apply the Dynamixel Protocol 1 or 2 depending on which DXL actuators you are actually using:

Basically you will need to build your own DXL Library. Are you sure that this is worth your time to reconstruct the ROBOTIS Dynamixel Library?

This person did it for the AX-12A in Python, each DXL has a unique ID 1-253.

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Well I may underestimate the difficulty of communication, but I just think what I only have to do is sending proper packet to dynamixel. For example, I expect just sending example packet in the Communication e-manual will work dynamixel well.

You said whether it is worth or not, and my answer is yes because I think this is the only solution I can do…

I really appreciate with your share of python example of toher people! I will look carefully that code.
Also I appreciate with your really kindness answers!

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