Serial and legacy cables connect older equipment that predates USB and HDMI, such as DB9 serial ports, DB25 parallel printer ports, PS/2 keyboards and mice, and analogue video outputs like VGA and S-Video. They suit anyone keeping industrial machinery, network switches, point-of-sale hardware or older monitors running. No products are listed in this category at the moment.
How to choose a serial or legacy cable
Connector type and gender. Count the pins and check the shape on both devices: DB9 and DB25 look similar at a glance but are not interchangeable. Then check whether each end is male (pins) or female (sockets), because a cable with the wrong gender will not fit at all.
Straight-through or null modem. A straight-through serial cable connects a computer to a device such as a modem or a console port. A null modem (crossover) cable swaps the transmit and receive lines so that two computers or two similar devices can talk to each other. Check the equipment manual to see which one it expects.
Length and signal quality. RS-232 is designed for short runs, and speed and reliability drop as the cable gets longer. Analogue video such as VGA also loses sharpness over long lengths. Measure the route between the devices and choose the shortest cable that reaches comfortably.
Shielding and build quality. Cables with shielding and metal-hooded connectors handle electrical interference better, which matters near motors, power supplies and other machinery. Screw-in thumbscrews hold a connector firmly in place, so they suit equipment that is moved or vibrates.
Cable or adapter. Most modern laptops have no serial port. If your computer lacks one, you may need a USB to serial adapter rather than a longer cable. Adapters differ in chipset and driver support, so check that the driver works with your version of Windows or Linux.
Brands in this category
- No brands listed yet: there are currently no products in this category, so there is no brand to recommend here.
- What to compare instead: pin count, connector gender, shielding, conductor wiring and stated length tell you more about a legacy cable than a logo does.
Related cables, adapters and other video connections can be found in the neighbouring Video cables and Wires, cables categories.
Frequently asked questions about serial and legacy cables
What is a serial cable used for?
A serial cable sends data one bit at a time between two devices. It is still common for configuring routers and switches, controlling industrial equipment, reading measuring instruments and running some older printers and card readers. The most familiar connector is DB9, which carries the RS-232 standard.
What is the difference between a null modem cable and a straight-through serial cable?
A null modem cable crosses the transmit and receive wires, while a straight-through cable connects each pin to the same pin at the other end. Use a null modem cable to link two computers or two data terminal devices directly. Use a straight-through cable between a computer and a device such as a modem.
Can I connect a serial device to a computer without a serial port?
Yes, a USB to serial adapter adds a virtual COM port to a computer that has none. Choose one that has drivers for your operating system, and check the device manual for the baud rate and settings it needs. Some adapters also need a null modem cable or adapter in addition.
Are VGA and other legacy video cables still worth buying?
They are worth buying if your monitor, projector or industrial display only has analogue inputs. VGA carries video but not sound, and its picture quality depends on cable quality and length. If both devices support HDMI or DisplayPort, a digital cable is usually the better choice.
