How to design a motion controller MC with multiple modules sharing a common ground?

Designing a common-ground system for multi-motion controller (MC) modules requires establishing a clear hierarchy and rules. A main grounding copper busbar or backplane ground plane should be set as the system's zero-potential reference. Each module should be connected to the main grounding point via a low-impedance grounding busbar or backplane grounding pin. Differential interfaces are preferred for signal connections between modules. If single-ended signals are used, ensure a good common ground at the transmitting and receiving ends, or connect a common-mode choke in series on the line. The backplane should provide a complete ground plane as a high-speed signal return path.

The power ground of each module should be connected to the backplane ground via a ferrite bead or small inductor to isolate its own switching noise. During installation, measure the resistance between each module's chassis and the main grounding busbar to ensure consistency and low resistance. The system software can add checks and retransmissions for communications susceptible to ground noise. After design, system-level radiated emissions and conducted immunity tests should be performed to verify the effectiveness of the common ground. For distributed systems, fiber optic communication can be used to completely avoid common-ground issues.