Description
Product Overview
The StarTech.com 4‑Port Serial Card (model PEX4S953) is a PCI Express adapter that adds four full‑profile DB9 RS232 ports to any compatible desktop or server. Built around the ASIX AX99100 chipset, each port supports bi‑directional data rates up to 921.6 kbps and includes a 256‑byte FIFO buffer for smooth data flow. The card measures 2.95 x 2.48 x 0.59 inches, weighs 1.76 oz, and ships with both a standard bracket and a low‑profile bracket for versatile installation.
Usage
Designed for point‑of‑sale terminals, PLCs, factory automation, scientific sensors, medical devices, scanners and oscilloscopes, this card excels in environments that require stable, high‑speed serial communication. Whether you are integrating legacy equipment into a modern Windows or Linux system, the configurable 12 V/5 V power pins allow you to power external devices directly from the card, reducing cable clutter and simplifying setup. 
Why Choose Us
StarTech.com is known for rigorous quality testing and long‑term support. This serial card benefits from driver updates for Windows XP and newer, as well as major Linux distributions, ensuring compatibility across a wide range of operating systems. The dual‑bracket design means you can fit the card into both full‑height and low‑profile chassis without additional modifications, and the included DB44‑to‑4×DB9 breakout cable streamlines wiring.
Key Features
- Four high‑speed RS232 ports up to 921.6 kbps per port
- Individually configurable 12 V, 5 V, or no power on pin 9 (up to 2 A total)
- Standard and low‑profile brackets included for flexible installation
- Compatible with Windows (XP and later) and Linux operating systems
- Compact PCIe form factor with 256‑byte FIFO buffers for reliable data handling
FAQ
Can each port be powered separately?
Yes, each of the four ports can be set to 12 V, 5 V, or left unpowered via pin 9, allowing up to 2 A total current across the card.
Is a driver required for Linux?
The card works with the built‑in ASIX driver in most modern Linux kernels, but StarTech provides optional driver packages for enhanced functionality.
What operating systems are supported?
Supported OSes include Windows XP, Vista, 7, 8, 10, 11 and major Linux distributions such as Ubuntu, Debian, and Red Hat.
Does the card fit in a low‑profile case?
Yes, a low‑profile bracket is included, enabling installation in cases with a 2.5‑inch height limitation.
Is the breakout cable included?
Yes, a DB44‑to‑4×DB9 breakout cable is packaged with the card for immediate deployment.




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