StarTech.com
4 Port PCI Express RS232 Serial Adapter Card
Best expansion solution for connecting multiple legacy serial devices to PCs.
Expand your computer's connectivity with the StarTech.com 4 Port PCI Express Serial Adapter Card. This card seamlessly adds four native RS232 (DB9) serial ports to your system via a PCIe slot, ideal for connecting devices like card readers, printers, and modems. It supports high-speed communication up to 921.6Kbps and offers broad compatibility across Windows and Linux operating systems. Installation is flexible with included full-profile and low-profile brackets for versatile mounting options. This adapter is designed for reliable performance and easy integration into your existing setup.
$77.00
Owner Satisfaction
4.6
/ 5
Category Rank
110
/ 1154
#110 in Computer Interface Cards & Adapters
Price vs Category Average
-86%
Below average
Number of Ports
4
Who it's for
- Industrial technicians managing multiple legacy serial devices
- System builders integrating hardware into modern motherboards
- IT professionals requiring stable, long-term driver support
Who should skip it
- Users uncomfortable with opening their computer chassis
- Budget-conscious buyers needing only basic serial connectivity
- Owners of compact cases with limited internal space
Performance breakdown
Data Throughput
High-speed 921.6Kbps transfer handles demanding industrial serial communication with ease.
System Efficiency
Significant CPU load reduction ensures your host system remains responsive under pressure.
Installation Versatility
Included low-profile brackets make this a perfect fit for compact workstations.
OS Compatibility
Broad driver support spans modern Windows, Linux, and legacy server environments.
Signal Reliability
The 256-byte FIFO buffer effectively prevents data loss during heavy traffic.
Power Flexibility
Pin 9 power output simplifies connectivity for specialized peripheral devices.
Key Specs
Number of Ports
4
Interface Type
Serial (RS-232)
Bus Type
PCI Express
Maximum Baud Rate
921.6 Kbps per port
FIFO Buffer Size
256 Bytes per transmitter and receiver
Connector Type
4 - DB-9 Male
Chipset ID
ASIX AX99100
Form Factor
Standard Profile PCIe Card (Low Profile Bracket Included)
Features
- Adds four native RS232 serial ports via PCIe
- Supports high-speed data transfer up to 921.6Kbps
- Includes 256-byte FIFO buffer per port
- Provides 5/12V power output on Pin 9
- Compatible with Windows and Linux
- Includes low-profile bracket for versatile installation
- Utilizes industry-standard 16950 UART
- Reduces CPU load by up to 46%
What customers say
Users consistently praise this serial adapter card for its exceptional compatibility and ease of installation. Professionals report a true plug and play experience, noting seamless driver recognition across numerous Windows and Linux operating systems, which greatly simplifies deployment. A dominant theme is the card's robust performance and stability, making it ideal for critical applications like industrial automation and specialized diagnostics. The ability to maintain consistent, error-free communication across all four ports ensures high operational reliability. While the initial cost may be higher than generic options, customers feel the investment is justified by the superior build quality and dependable functionality, offering significant peace of mind.
Know before you buy
Yes. The card includes both full-profile and low-profile brackets, making it compatible with both standard desktop towers and compact, small form factor systems.
Yes, this card supports 5V or 12V power output on Pin 9, which is useful for powering specific serial peripherals like barcode scanners or specialized card readers without needing an external power supply.
This card provides a native RS232 serial connection via the PCIe bus. Using a native 16950 UART chipset ensures better reliability and lower CPU usage compared to USB-to-serial adapters.
The adapter is widely compatible with modern systems, including Windows 11, Windows Server editions, Linux (kernel 2.6.x and up), and macOS 10.12 and later.
Each of the four ports supports high-speed data transfer rates of up to 921.6Kbps, which is sufficient for most industrial and legacy serial communication requirements.
No. Because it utilizes an industry-standard 16950 UART and handles data processing on the card itself, it can reduce CPU load by up to 46% compared to older or software-based serial solutions.
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