What "Serial" Means in Industrial Computing
In industrial and commercial computing, "serial" almost always refers to a serial port — a legacy-but-still-essential communications interface that sends data one bit at a time over a single pair of wires. The most common physical implementation is the RS-232 standard, usually presented on a 9-pin DB9 connector and addressed by the operating system as a COM port (COM1, COM2, and so on). RS-232 remains the default language of barcode scanners, weighing scales, label printers, PLCs, energy meters, medical devices, GPS receivers, and countless pieces of installed equipment that will keep working for decades.
Serial is also the reason many buyers search for industrial hardware: USB and Ethernet are faster, but they are not always electrically rugged or deterministic enough for factory floors, outdoor kiosks, or legacy retrofits. Serial ports are simple, cheap to cable, tolerant of long runs (especially RS-485), and free from the driver churn that affects USB adapters. For equipment that must be polled every few milliseconds or that must survive a power dip, a native hardware serial port is often the most reliable option available.
RS-232, RS-485 and RS-422 Compared
The three standards share a data format but differ in electrical behaviour, distance and topology. Choosing the right one determines how far you can run cable, how many devices you can address, and how well the link survives electrical noise.
| Feature | RS-232 | RS-485 | RS-422 |
|---|---|---|---|
| Signalling | Single-ended | Differential | Differential |
| Typical distance | ~15 m | ~1200 m | ~1200 m |
| Max devices on |
