Serial and parallel adapters connect older RS-232 and parallel (printer) equipment to modern computers, or convert one standard to another. Our range of over 40 models covers USB-to-serial and parallel adapters, converters and interface cables from EFB Elektronik, Micro Connect, Delock, Zebra and HP.
They suit offices, workshops and shops that still run label printers, scanners, tills, CNC machines or network equipment.
How to choose a serial or parallel adapter
Connection on the computer. Most laptops and desktops now offer only USB, so a USB-to-serial or USB-to-parallel adapter is the usual route. If you need several ports in one machine, check whether a multi-port adapter or an expansion card suits your setup better.
Port standard on the device. RS-232 is the common serial standard, but some industrial equipment uses RS-422 or RS-485, which need a different adapter. Parallel printers typically use a Centronics or DB25 connector, so check the plug on the old device before ordering.
Connector type and gender. Serial ports come as 9-pin (DB9) or 25-pin (DB25), as male or female. A mismatch means a second gender changer or adapter cable, so compare both ends against your equipment.
Driver and chipset support. The chipset inside a USB adapter decides how well it works with Windows 11, macOS or Linux. Look for a stated operating system list on the product page, especially if the adapter drives a measuring instrument or a machine where a dropped connection causes problems.
Cable length and build. A short adapter hangs from the port, while a cable version puts the converter closer to the device. For fixed installations, choose a sturdy housing and secure screw-down connectors.
Serial and parallel adapter brands we carry
- EFB Elektronik: a German supplier of cables and connectivity accessories, and the largest brand in this category in our range.
- Delock: known for interface adapters, converters and expansion cards for many connection standards.
- Digitus: the in-house brand of ASSMANN Electronic, focused on network and connection cabling.
- EXSYS: a German manufacturer specialising in serial interface cards and industrial I/O products.
- Roline and Value: both are Secomp brands for cables and adapters, aimed at office and installation use.
- Zebra and Datalogic: both are best known for barcode scanners and label printers, so their items here suit point-of-sale and warehouse equipment.
- HP: a major maker of PCs and printers, with connection accessories for its own hardware.
Also in our range: Micro Connect, Gembird and InLine.
Frequently asked questions about serial and parallel adapters
Can I connect a serial device to a laptop with only USB ports?
Yes, a USB-to-serial adapter does this. It creates a virtual COM port in the operating system, which most older software can use. Check that the adapter has drivers for your Windows or macOS version.
What is the difference between RS-232 and a parallel port?
RS-232 sends data one bit at a time over a few wires, while a parallel port sends several bits at once over many wires. Serial is used for modems, scanners, tills and machine controls. Parallel was mainly used for older printers.
Will a USB-to-parallel adapter work with any old printer?
It works with most printers that use a standard Centronics interface, but not always with every function. These adapters are designed for printing and often do not support scanners or dongles that need direct port access. Check the product notes before buying.
Do I need a null modem cable or a straight cable?
Use a straight cable when connecting a computer to a peripheral such as a modem or scanner. A null modem cable swaps the transmit and receive lines and is needed to connect two computers, or two devices of the same type, directly. The device manual usually states which one applies.
