# StarTech.com 4-port PCI Express RS232 Serial Adapter Card PCIe to Serial DB9 16950 UART

**URL:** https://aio.lv/en/product--startech-pex4s953--10974040
**Data updated:** 2025-12-30 15:00 (EET)
**Category:** I/O Adapters & Controllers
**Manufacturer:** StarTech
**Manufacturer code:** PEX4S953
**EAN:** 0065030888257
**Warranty:** 2 Years
**Availability:** Available for order
**Price:** 145.49 €
**Prices and availability valid until:** 2026-07-17 23:59
**Price without VAT (21%):** 120.24 EUR
**Can be purchased by legal entities:** Yes (invoice)
**Buy:** https://aio.lv/en/product--startech-pex4s953--10974040

## Delivery options

| Delivery method | Delivery time | Cost |
|---|---|---|
| Office pickup (2b. Kengaraga str., Riga, Latvia, LV-1063) | 03.07.2026 | free |
| Pickup points | 08.07.2026 | 1.99 EUR |
| Courier delivery to door | 08.07.2026 | 4.99 EUR |

## Summary description

The StarTech.com 4-port PCI Express RS232 Serial Adapter Card features a PCIe interface, supports baud rates up to 921.6 Kbit/s, and is compatible with Windows and Linux operating systems. Ideal for adding multiple serial connections to your system.

## Long description

The StarTech.com 4-port PCI Express RS232 Serial Adapter Card (PEX4S953) adds four DB9 serial ports to a computer via a PCI Express (PCIe) slot, providing native-like serial connectivity with support for baud rates up to 921.6 Kbps. The card is based on the ASIX AX99100 chipset, features a 16950-compatible UART and is compatible with Windows and Linux. It ships with a full-size bracket and an optional low-profile bracket for flexible installation in various system form factors.
Advantages
This PCIe to serial DB9 adapter offers four bi-directional RS232 ports with a 256-byte FIFO for each transmitter and receiver, enabling reliable high-speed serial communication. It supports configurable Pin 9 power (5 V/12 V/none) when external power is provided, and each port can be configured individually. The adapter is PCI Express 1.1 compliant and is supplied with both standard and low-profile brackets for easy installation in different chassis.
Suitable for
Connecting legacy serial devices such as card readers and POS peripherals
Attaching industrial equipment, PLCs and modems
Integrating PIN pads and serial printers in point-of-sale systems
Upgrading workstations or servers that require additional RS232 ports
Key specifications
Model: PEX4S953
Interface: PCI Express (PCIe) — PCIe 1.1 compliant
Serial ports: 4 x DB9 RS232
UART: 16950-compatible (ASIX AX99100 chipset)
Maximum baud rate: 921.6 Kbps per port
FIFO: 256-byte depth per transmitter and receiver
Pin 9 power output: configurable 5 V / 12 V / none (requires external power)
Brackets: full-size pre-installed and optional low-profile
OS compatibility: Windows and Linux
Product colour: green
How to use
Install the adapter into an available PCIe slot on the host computer and secure the appropriate bracket for your chassis. If external power is needed for Pin 9 power output, connect the required power source according to the system documentation. Install drivers for your operating system if needed (Windows and Linux supported) and connect serial devices to the DB9 ports using the included DB44-to-4x DB9 breakout cable or standard serial cables. Configure port settings (baud rate, data bits, parity, stop bits) in your OS or application to match the connected devices.
Usage recommendations
For reliable operation at high baud rates, use short, shielded serial cables and ensure a stable external power supply when using Pin 9 power. Verify driver compatibility with your specific OS version and test each port after installation to confirm proper communication settings.

## Specifications

### Operational conditions

| Feature | Value |
|---|---|
| Operating relative humidity (H-H) | 5 - 85 |
| Storage temperature (T-T) | -20 - 100 |
| Operating temperature (T-T) | -10 - 80 |

### Technical details

| Feature | Value |
|---|---|
| Sustainability certificates | RoHS |

### Ports & interfaces

| Feature | Value |
|---|---|
| Serial interface type | RS-232 |
| Serial ports quantity | 4 |
| Host interface | PCIe |
| Output interface | Serial |
| Expansion card form factor | Full-height / Low-profile |

### Other features

| Feature | Value |
|---|---|
| Quantity | 1 |

### Weight & dimensions

| Feature | Value |
|---|---|
| Weight | 0.05 kg |
| Package weight | 371 g |
| Height | 15 mm |
| Width | 63 mm |
| Depth | 75 mm |

### System requirements

| Feature | Value |
|---|---|
| Windows operating systems supported | Windows 10 Home, Windows 10 Pro x64, Windows 10 Pro, Windows 10 IoT Enterprise, Windows 10 IOT Core, Windows 10 Home x64, Windows 7 Enterprise x64, Windows 10 Enterprise x64, Windows 10 Enterprise, Windows 10 Education x64, Windows 10 Education, Windows 10, Windows 10 x64, Windows 7, Windows 7 Enterprise, Windows 7 Home Basic, Windows 7 Home Basic x64, Windows 7 Ultimate, Windows 7 Home Premium, Windows 7 Home Premium x64, Windows 7 Professional, Windows 7 Professional x64, Windows 7 Starter, Windows 7 Starter x64, Windows 7 x64, Windows 8.1 x64, Windows 8.1 Pro x64, Windows 8.1 Pro, Windows 8.1 Enterprise x64, Windows 8.1 Enterprise, Windows 8.1, Windows 8 x64, Windows 8 Pro x64, Windows 8 Pro, Windows 8 Enterprise x64, Windows 8 Enterprise, Windows 8, Windows 7 Ultimate x64 |
| Linux operating systems supported | Y |
| Server operating systems supported | Windows Server 2016, Windows Server 2012 R2, Windows Server 2012, Windows Server 2008 R2, Windows Server 2003 |

### Design

| Feature | Value |
|---|---|
| Internal | Yes |
| Product colour | Green |

### Performance

| Feature | Value |
|---|---|
| Certification | CE, FCC, Microsoft WHQL |
| Mean time between failures (MTBF) | 214358 h |
| Chipset | Asix AX99100 |

### Logistics data

| Feature | Value |
|---|---|
| Master (outer) case height | 240 mm |
| Master (outer) case width | 340 mm |
| Master (outer) case length | 480 mm |
| Products per master (outer) case | 16 pc(s) |
| Harmonized System (HS) code | 84733020 |

### Features

| Feature | Value |
|---|---|
| Baud rate | 921.6 Kbit/s |
| Data bits | 6, 5, 7, 8, 9 |
| Stop bits | 1, 1.5, 2 |
| Parity bit | Even, Mark, N, Odd, Space |
| Flow Control type | XON/XOFF, N, RTS/CTS |
| FIFO (First In, First Out) | 256 |

### Packaging data

| Feature | Value |
|---|---|
| Cables included | Serial |
| Package depth | 210 mm |
| Package height | 50 mm |
| Package width | 150 mm |
| Quick installation guide | Yes |
| Mounting brackets included | Yes |

## FAQ

### How much does the StarTech.com 4-port PCI Express RS232 Serial Adapter Card cost, and is it available for purchase?

The price is 145.49 € (valid at the time of publication and already includes all taxes). The item is available for order — 14 pcs. are in stock, and you can place your purchase right now with delivery across Latvia and Europe or choose pickup at the Riga collection point. We offer favorable purchase terms, including the option to split the payment into convenient monthly installments. Availability and price are updated in real time, so we recommend placing your order in advance.

### If I order this product today, when will I receive my order?

If you place your order today, delivery will be as fast and convenient as possible. You will be able to pick up your order on 03.07.2026 at the Riga pickup point or choose delivery across Latvia and Europe. We carefully inspect every purchase and pack it securely for safe transportation.

### What payment options are available?

AiO.lv offers several payment methods: Bank transfer. All transactions are 100% secure and encrypted.

### Can this product be purchased for a company (with VAT)?

Yes. AiO.lv works with legal entities in Latvia and across Europe. The product price already includes VAT. For certain product categories, as well as for companies from other EU countries with a valid VAT number, a 0% VAT rate may apply. We issue the invoice immediately after the order is placed, support electronic BIS invoices, and automatically generate all necessary accounting documents. You can complete the purchase for a company online — simply select the company profile and choose bank transfer as the payment method during checkout.

### What is the warranty period?

All StarTech products come with an official 2 Years warranty. It covers all manufacturing defects and malfunctions that may occur during use. The warranty is valid at all authorized StarTech service centers and through AiO.lv

### Can the product be returned after purchase?

Yes, you can return the product within 14 days of purchase if you bought it as a consumer (not a legal entity). Returns are possible without giving any reason — the main condition is that the product retains its original appearance and full set of accessories. We will make the process as simple and convenient as possible: just contact our customer support team, and we will help you arrange the return.

### Where should I contact for warranty service?

For warranty-related questions you can contact the AiO.lv (SIA VSPRO) customer support team. More information about warranty service: https://aio.lv/en/warranty

### How can I tell if this product suits my needs?

When making a choice, we recommend paying attention to the key features: host interface, weight, internal, output interface, product colour, compatibility with your devices or usage conditions, material quality, functionality, and warranty terms. These characteristics will help you determine how well the model meets your needs.

### Where can I download the instructions for StarTech.com 4-port PCI Express RS232 Serial Adapter Card?

You can download the instructions in PDF format from the “Instructions” section on the product description page. The file contains complete information about installation, setup, and usage.

## Image

https://aio.lv/img/cache/product/10974040/61396702_large.webp