Pc+Com+Porta+Serial - PC with Serial Port: Fanless Industrial COM Port PCs

What "PC with Serial Port" Means

A PC with a serial port (also called a COM port) is a computer that exposes one or more RS-232, RS-422 or RS-485 communication interfaces, usually on a 9-pin DB9 connector, alongside standard USB, HDMI and Ethernet ports. Serial ports are the oldest and still the most trusted way to talk to industrial equipment: PLCs, weighbridges, energy meters, barcode scanners, CNC controllers, medical analysers, access-control panels and point-of-sale peripherals. Because the interface is simple, deterministic and electrically robust over long cable runs, it survives where USB and network protocols become fragile. On a modern industrial PC, the serial ports are driven by a dedicated controller rather than a USB-to-serial adapter, which means stable COM port numbering, low latency and reliable operation around the clock.

Serial Standards and Electrical Details

RS-232 is the classic point-to-point standard: single-ended signalling with levels of roughly ±3 V to ±15 V, a maximum recommendable cable length around 15 m and speeds typically from 300 baud to 115200 baud. RS-422 uses differential signalling for full-duplex links up to about 1200 m. RS-485 is also differential but supports multi-drop buses with up to 32 (or 256 with low-load transceivers) devices on the same two wires, commonly in half-duplex mode. Many industrial computers let each DB9 port be configured as RS-232, RS-422 or RS-485, with selectable termination resistors and optional 1.5 kV or 2.5 kV galvanic isolation plus surge and ESD protection — important when a machine is wired across different ground potentials in the same plant.