| Product Type | Serial Adapter Card |
| Form Factor | Plug-In Card |
| Chipset | ASIX AX99100 |
| UART Type | 16950 UART |
| FIFO Buffer | 256 byte FIFO per port |
| Maximum Data Rate | 921.6 Kbps per port |
| Bracket Type | Standard profile (low profile bracket included) |
| External Cable | Breakout cable for 4 x DB9 serial ports |
| Weight | 76 g |
| Power Output on Pin 9 | Selectable 5V / 12V / None (up to 2A total) |
| Operating System Support | Windows, Linux |
StarTech 4-Port PCIe RS232 Serial DB9 Adapter Card PEX4S953

Key Benefits
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- Offers high-speed, bi-directional serial connectivity for up to four devices via one PCIe slot, boosting efficiency and reducing expansion overhead.
- Built-in voltage selection per port (up to 2A shared) supports a wide range of powered serial equipment without external adapters.
- Includes full and low-profile brackets plus cross-platform support (Windows/Linux), enabling seamless deployment across varied hardware setups.
Product Overview
4 port PCI Express RS232 serial controller card w/16950 UART/ASIX AX99100 - Bi-directional speeds 921.6Kbps/port / 256 byte FIFO / 9th data bit - Pin 9 pwr out 5v/12v/none w/up to 2A total - Std bracket (low profile incl); Breakout cable - Win/LinuxSpecifications
Product Overview
Physical & Environmental
| Dimensions (W x D x H) | 120 mm x 92 mm x 18 mm |
| Operating Temperature | 0°C to 55°C (32°F to 131°F) |
| Storage Temperature | -20°C to 85°C (-4°F to 185°F) |
| Humidity (Operating) | 5% to 95% RH (non-condensing) |
Cloud Management & Licensing
| Management Interface | |
| Cloud-based Management | |
| Included Licensing |
Interfaces
| Interface Type | PCI Express 1-lane (PCIe x1) |
| Port Type | DB9 male |
| Number of Ports | 4 |
| Compatible Slot | PCI Express x1, x4, x8, x16 |
| Serial Protocol | RS-232 |
| Connectivity Technology | Wired |
Compliance & Origin
| TAA Compliant | Yes |
| Country of Origin | Taiwan |
| Certifications | CE, FCC, RoHS, REACH |
Advanced Security Features
| Integrated Security | |
| Surge Protection | 15kV ESD protection on all signal lines |
| Isolation | None |