Pinout review becomes especially important when the upgraded machine mixes cameras, PLC communication, IO blocks, and edge gateways. Those devices may all speak Ethernet, but they do not forgive sloppy shielding or pair routing. The engineering team should map the data path from device port to connector, cable, cabinet entry, and switch, then verify the connector pinout and mating interface before procurement signs off. That sounds tedious; it is cheaper than opening a cabinet after a failed factory acceptance test. X-coded M12 connectors are designed to avoid accidental mismating with other codings, and that mechanical distinction helps service teams when several round connectors sit on the same panel. The same thinking applies to documentation. A retrofit should leave behind a clean parts list and a clear connector note for the next maintenance crew, otherwise the plant saves money during installation and spends it again the next time someone opens the panel.