Mechanical configuration

Another important consideration regarding how, and how much, you can use a network-based approach, is the mechanical organization of your machine. This issue addresses questions such as “How will the machine be serviced if electronics are physically distributed throughout the machine?” The cost reduction anticipated due to reduction in wiring must be compared against the cost of servicing the whole system in the field. Although the traditional card rack that the technician services may be a mess of wires, there is something to be said for

In a flat motion control application, all motors are directly controlled by the central PC.

Axes in a hierarchical motion control applilcation are grouped together and controlled locally.

keeping everything under-one-roof. Serviceability and lifetime ownership cost issues strongly affect control system design choices.

Remember also that distributing the control by placing amplifiers near the motors may not always be feasible for weight, heat, or other environmental reasons. The traditional control rack cabinet can be air conditioned and insulated from the machine environment relatively easily but is often not possible if the controls are distributed.