U2D2 vs OpenCM9.04?


MX-106T and MX-64T, U2D2 and OpenCM9.04 + OpenCM485EXP

Issue Description

Not an issue but a question as to which one is better. Are there any perks for using the U2D2 over the OpenCM9.04 or vice versa? any performance differences to take note of?

The U2D2 is just a Serial Converter from USB to Half-Duplex UART, i.e., “no brain” on the U2D2, you still need to use a PC or SBC like RPi to control your servos, and then you’ll have to use the Dynamixel SDK.

The OpenCM9.04 is a Controller board so it does have a “brain” plus the Serial Converter hardware, so you can program/control your servos with it, using TASK or Arduino for example. But its MCU is not powerful as your PC’s. But you can hook all kind of peripherals to the OpenCM9.04 and “nothing else” on the U2D2 (other than your servos).

The U2D2 and Open series of controllers are actually very different devices!

The U2D2 is just a USB to Serial communications converter, not a controller at all. The U2D2 can’t be used on it’s own, and must be connected to a PC or other device that will actually control the connected DYNAMIXELs.

The OpenCM and related controllers, including the new OpenRB-150, are fully featured microcontrollers. They can be programmed to operate DYNAMIXEL actuators on their own, and also support the integration of external sensors through their numerous analog and digital input pins.

Thanks for the response @Jonathon and @roboteer ! The reason why I ask is because I am currently in the fence with which one to use. My hardware application requires a PC/SBC to communicate to the dynamixels via serial communication since the data is modified from a different computer. So even if I use an OpenCM9.04, I still need to have it connected to the PC/SBC for serial communication.

In this kind of scenario, would a U2D2 work better? can the OpenCM9.04 work jsut as well?

In your case a U2D2 is better because the U2D2 can communicate to the DXLs up to 6 Mbps. However don’t forget that the SBC usually has a USB latency of 16 ms that slows the U2D2 down.