You're going to have to give us some details of your system before anyone will be able to help you with this. Can you describe the hardware you're trying to connect to for us.

Hello PeteBlacker,

I just research from Google for how to make robot by ROS, for example to make ARM for handling industry procedure, how to connect mechanism and how to control robot for real world use ?

Thanks

I guess that depends on a lot on stuff like which microcontroller you are using, the type of motors you have, no. of degrees of freedom for the arm( the math changes with different configs), the kind of communication you want to setup (wired/wireless) etc. Could you please elaborate on that?