How to resolve the interference between the intelligent controller PAC IO and motion control?

To resolve the mutual interference between the I/O and motion control circuits (such as pulse output and encoder feedback) of the intelligent controller PAC, frequency separation and physical isolation are required. The high-frequency motion control signal (>1MHz) and the low-frequency I/O signal are separated by a ground plane for isolation. The motion control signal uses differential transmission (such as LVDS) with a common-mode inductor (CMZ20212A-900T). The I/O signal uses optocoupler isolation. The power supply provides independent windings for motion control and I/O, and uses a ferrite bead (PBZ1608A-102Z0T) for isolation.

On the PCB, the motion control area uses a complete ground plane, and traces are avoided below the I/O area. In software, the refresh cycles of motion control and I/O are staggered. Tests show that this solution can improve motion control accuracy (positioning error less than ±1 pulse), reduce the I/O malfunction rate to 0.001%, and meet the IEC61000-4-4 EFT 4kV and IEC61000-4-8 power frequency magnetic field immunity tests.