I plan to use the OpenRB-150 controller to operate six MX-28 DYNAMIXEL servos, and I have some questions regarding the power supply configuration.
From the official datasheet, I understand the OpenRB-150 has three power supply options. When the jumper is set to VIN(DXL), supplying 11.1V to the Terminal VIN powers both the OpenRB-150 board and the connected MX-28 motors through the board’s DYNAMIXEL ports.
However, I have encountered information (in previous posts/discussions) suggesting that the OpenRB-150 might experience overheating issues when operating at 12V.
Therefore, I would like to adopt a safer approach: to power the OpenRB-150 board itself with 5V and power the MX-28 motors with 12V.
My question is:
If I supply 11.1V(or 12V) to the Terminal VIN(for the motors) AND supply 5V to the 5V VIN pin on the board (for the controller logic), with the jumper set to 5V,will the TTL output pins still be supplied with the 11.1V (or 12V) from the Terminal VIN for the DYNAMIXELs?
For my OpenRB-150 projects, I never let any 12 V wires “touch” the OpenRB-150 so I don’t even use that PS Terminal Block on the OpenRB-150. So I would power the MX-28 DXLs at 12 V as normal via their own PS and using the regular 3P Molex cables. From the OpenRB-150’s end I put the Jumper on 5V and from the X3P Hub on the OpenRB-150, I used a “modified” X3P Convertible Cable to connect the 150 to the “last” MX-28 of the daisy chain. See this link if you do not have these X3P compatible cables yet.
This cable is "modified" by cutting out the VDD line (which carries the 12 V from the MX-28 daisy chain) >> this way the 12 V circuit is isolated from the OpenRB-150 completely, but the MX-28s still share their GND line with the OpenRB-150, and also their DATA lines (5V TTL) with OpenRB-150 >> therefore you still can use your Arduino code to control the MX-28s.
You can check out my newest application of this approach at this posting for OMX:
If you are interested in more Arduino Applications with OpenRB-150, you can check this free Amazon Kindle sample at this link
However using SIX MX-28s in ONE daisy chain has an additional and different kind of Power & Control Issue also. Please read these two posts also
You can try first with only 1 12V PS and ONE daisy chain. But you most likely will need 2 separate PS at 12 V, each for 1 daisy chain of 3 MX-28s, and two “special” X3P compatible cables coming from the OpenRB-150 to control each of the two MX-28 daisy chains.