Serial Ports Aren't Dead
While consumer tech abandoned the COM port decades ago, the industrial world still runs on it. PLCs, CNC controllers, barcode scanners, and environmental sensors rely on robust, deterministic serial communication.
| Standard | Topology | Max Distance | Signal Type |
|---|---|---|---|
| RS-232 | Point-to-Point | ~15m | Single-ended |
| RS-422 | Multi-drop (1 Tx, 10 Rx) | ~1200m | Differential |
| RS-485 | Multi-point (32 nodes) | ~1200m | Differential |
Why RS-485 Survives
RS-485 uses differential signaling over twisted pair wiring. If electrical noise (EMI) from a massive factory motor hits the cable, it affects both wires equally. The receiver looks at the difference between the wires, effectively canceling out the noise. This allows for massive cable runs across factory floors.