Serial Cables

Serial cables and RS-232 leads for the equipment that has never stopped using them — PLCs, barcode scanners, receipt printers, till systems, UPS management ports, switch consoles, laboratory instruments and building management panels.

Straight-through or null modem

This is the decision that decides whether the link works at all. A straight-through DB9 lead connects a computer to a peripheral — a DTE to a DCE — and passes each pin to its opposite number. A null modem lead crosses transmit and receive so that two DTE devices, two computers or two controllers, can talk to each other. The connectors are identical and the cables are frequently unmarked, which is why most serial faults on a bench turn out to be the wrong one of the two. Both types are stocked, in male-to-female and male-to-male, with DB-25 to DB-9 leads for older instrumentation.

USB to serial converters

Few machines still ship with a COM port, so most new serial work runs through a USB adapter. The chipset is what you are actually buying. FTDI parts have the broadest and best-maintained driver support across Windows, macOS and Linux, and are the safe choice for anything that has to keep working after an OS upgrade. Prolific parts are commonly cheaper and are fine for general use. USB-C to RS-232 leads cover current laptops directly. Where an adapter has to stay bound to the same COM number across reboots, look for COM port retention — it is the difference between a configured application and a support call every time the device is unplugged.

Brands

StarTech.com, Microconnect, Manhattan, Aten, VivoLink, Moxa, iogear, Honeywell and Zebra, in lengths from 0.3 m to 30 m.

Trade pricing and business accounts are available for UK organisations, and bulk orders are welcome — request a quote.