How to ensure EMC of pre-installed cables for I/O modules?

Ensuring the EMC performance of prefabricated I/O module cables requires comprehensive control throughout the design, material selection, production, and testing processes. The EMC requirements for the cables, such as shielding type, shielding coverage, and characteristic impedance, should be clearly defined during the design phase. High-quality shielding materials should be selected, such as high-coverage braided layers combined with aluminum foil shielding. The internal cable structure should use twisted pairs, with the twist pitch optimized according to the signal frequency. Connectors must be metal-shelled or have an effective shielded connection structure.

During production, ensure reliable termination of the shielding layer at the connector, achieving a 360-degree low-impedance connection, and use stress-relief mechanisms to protect the termination points. For specific applications, ferrite cores or filter connectors can be integrated into the prefabricated cables. Each batch of products should undergo sampling testing, including: shielding layer transfer impedance testing to evaluate its shielding effectiveness; characteristic impedance testing; and actual EMC performance testing, such as connecting the cable to the module for radiated emission testing. Furthermore, the cables should be clearly labeled with type, length, and orientation to facilitate correct installation and use.