Multiple USB2Dynamixels

[HyperCube]

I have a project involving control of two separate arms using AX-18F's, from a single computer running the C++ USB2Dynamixel API.

I'm hoping to run each arm on its own bus. I think I remember reading a tutorial somewhere on how to run more than one USB2Dynamixel on a single computer, but I don't remember the link! (Don't you hate it when that happens?). Since then I've found some posts hinting that it's possible.

Has anyone had any luck doing it? What's involved exactly?

[i-Bot]

Do you really need a seperate bus for each arm ? You could power them from seperate batteries, but still share the ground and signal for a common bus provided you take care with the ground wiring.

Two USB2Dynamixel will appear as two different COM ports. I assume you use the Robotis Dynamixel API. I think the dxl_initialise sets the COM port and it is then used until dxl_terminate. Two COM ports would mean calling this pair quite often, so may be slow.

There is some sourcecode for driving dynamixels which could be modified for two ports.

[HyperCube]

The main reason I'm planning on using two buses is because it will allow me to easily control each robot independently without worrying about how they're sharing the bus. For example, if robot 2 wants to do something simple like poll the temperature for each servo, but robot 1 is hogging the bus because it's doing really tight high-frequency closed loop control, then robot 2 will have to wait until the bus is free (with only one bus).

I've gone through the dynamixel API and have a fairly solid idea of how to do it. All I need now is some hardware to play with....