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Six point six foot USB-A to DB9 serial adapter cable with interchangeable nuts

StarTech.com

STARTECH USB to Null Modem Serial Adapter Cable 6.6ft

SKU CH-RHRS-P3M1Z

Connects USB ports to RS-232 serial equipment with a 6.6ft cable and interchangeable DB9 hardware

  • 6 ft cable reaches distant serial ports easily
  • USB-A to DB9 RS232 connects legacy gear to modern PCs
  • FTDI chipset keeps COM port settings after reboot
  • Interchangeable DB9 screws or nuts secure the link
  • Works with Windows, macOS and Linux out of the box

What the adapter does

This StarTech USB to Null Modem Serial Adapter Cable adds a DB9 RS232 port to a computer that lacks a native serial interface. It suits engineers, technicians and hobbyists who must configure routers, switches, industrial controllers or legacy lab equipment over a direct null-modem link.

Interface limits

The connection uses USB-A on the host side and a male DB9 on the device side, with FTDI chipset handling the USB-to-serial translation. Cable length is 6.6ft (2m), so the linked equipment must sit within that distance; longer runs need a powered repeater or a different medium.

Installation notes

Driver support covers Windows, macOS and Linux, and the FTDI device usually enumerates automatically on modern kernels. The DB9 connector ships with interchangeable screws and nuts; mismatched hardware is the most common snag, so verify the mating panel before tightening. COM-port retention keeps the same port number across reboots.

How it compares

Measured against everything we stock in Other Adapters & Couplers, at today’s prices. Recalculated every night.

Price $32.99
Pricier than about 80% of the 1,755 comparable items (median $18.99).

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Specifications

Product
Brand nameStarTech
Size & build
Shipping weight0.45 kg
Package size229 × 155 × 84 mm

Questions about this item

Should I pick the 6.6ft cable or a shorter length for my serial device?

The 6.6ft length gives enough reach for most bench or rack setups without excess slack.

What does the FTDI chip actually do when the adapter is plugged into a real machine?

It presents a virtual COM port so legacy RS232 gear appears as a standard serial device to the OS.

Which serial standard does the DB9 end follow and what does that limit in practice?

The DB9 connector follows RS232 signalling so voltage levels and cable length stay within that specification.

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