How to ground the shielding of I/O module field cables?

Properly grounding the shielding layer of I/O module field cables is crucial for maximizing its shielding effectiveness. The basic principle is that the shielding layer should be grounded at a single point, either at the interference source or the receiving end, avoiding grounding at both ends to prevent ground loops. Grounding at the control cabinet or I/O module end is typically preferred as it is usually cleaner and more controllable. The grounding method must be a 360-degree low-impedance connection, such as using cable connectors or shielding clips with shielded connection capabilities, evenly pressing the shielding layer onto the metal connector housing, which then makes good contact with the metal housing of the cabinet or module. Never twist the shielding layer into a single strand and connect it to the grounding terminal. For high-frequency interference, grounding at both ends of the shielding layer is sometimes necessary to maintain shielding integrity; however, in this case, a ferrite core or common-mode choke must be installed on the cable to suppress low-frequency interference caused by ground loop currents. For composite cables containing multiple signal groups, each twisted pair should ideally have an independent sub-shielding layer. All sub-shielding layers should be insulated from the overall shielding layer and grounded only at one point. After installation, the continuity resistance of the shielding layer grounding should be checked.