# PCIe RS232 Serial Adapter Card 4-port, StarTech PEX4S953, 16950 UART, AX99100, Full/Low-profile

**URL:** https://aio.lv/en/product--startech-pex4s953--3455913
**Data updated:** 2026-03-11 11:43 (EET)
**Category:** I/O Adapters & Controllers
**Manufacturer:** StarTech
**Manufacturer code:** PEX4S953
**EAN:** 0065030888257
**Warranty:** 2 Years
**Availability:** Available for order
**Price:** 148.49 €
**Prices and availability valid until:** 2026-07-18 23:59
**Price without VAT (21%):** 122.72 EUR
**Can be purchased by legal entities:** Yes (invoice)
**Buy:** https://aio.lv/en/product--startech-pex4s953--3455913

## Delivery options

| Delivery method | Delivery time | Cost |
|---|---|---|
| Office pickup (2b. Kengaraga str., Riga, Latvia, LV-1063) | 10.07.2026 | free |
| Pickup points | 15.07.2026 | 1.99 EUR |
| Courier delivery to door | 15.07.2026 | 4.99 EUR |

## Summary description

StarTech PEX4S953 is a 4-port PCI Express RS232 serial adapter card with 16950 UART and Asix AX99100 chipset. It provides four DB9 serial ports via a PCIe host interface, supports up to 921.6 Kbit/s baud rate and 256 B FIFO, and fits full-height and low-profile slots. Certified CE/FCC/WHQL, MTBF 214,358 h. Suitable for industrial devices, legacy equipment, POS and serial peripherals on Windows and Linux.

## Long description

The StarTech PEX4S953 is a 4-port PCIe RS232 serial adapter card that adds four DB9 serial ports to a computer via a PCI Express slot. Based on the Asix AX99100 chipset with 16950-compatible UART functionality, the card supports data rates up to 921.6 Kbit/s and 256-byte FIFO buffers per transmitter and receiver. It ships with a full-height bracket and an optional low-profile bracket for installation in a wide range of system enclosures and is certified to CE, FCC and WHQL standards.
Advantages
This PCIe to serial adapter provides four independent RS232 ports with 16950 UART compatibility, enabling reliable communication with legacy and industrial serial devices. With support for high baud rates up to 921.6 Kbit/s and 256 B FIFO, the card reduces CPU overhead for bursty serial traffic. The inclusion of both full-height and low-profile brackets simplifies fitting the card into standard and small form-factor systems, while broad OS compatibility and industry certifications help ensure predictable integration in professional environments.
Suitable for
Connecting legacy serial peripherals such as barcode scanners, modems and POS devices
Industrial equipment and automation controllers that require RS232 interfaces
Point-of-sale (POS) systems and payment terminals that use DB9 serial connections
Laboratory and test setups requiring multiple serial ports on a single host
Key specifications
Interface: PCI Express (PCIe) host connection
Serial ports: 4 × RS232 (DB9) ports
UART compatibility: 16950-compatible UART
Maximum baud rate: up to 921.6 Kbit/s
FIFO: 256-byte depth per transmitter and receiver
Power output: 5/12 V available on Pin 9 when external power is connected
Form factor support: full-height and low-profile brackets included
Chipset: Asix AX99100
Compliance: CE, FCC, WHQL
Reliability indicator: Mean time between failures (MTBF) reported
How to use
Install the PEX4S953 into an available PCIe slot on the host system, selecting and attaching the appropriate bracket for the case (full-height or low-profile). If required by your serial devices, connect an external power source to enable 5/12 V output on Pin 9 of the DB9 ports. Install the appropriate drivers for your operating system (Windows or Linux) and verify each COM port is recognized in the OS device manager or serial port listing. Configure serial parameters such as baud rate, data bits, parity and stop bits to match the connected equipment before initiating communication.
Usage recommendations
Match the card’s serial port settings to the attached devices (baud rate up to 921.6 Kbit/s, data bits and parity) and, when using power on Pin 9, confirm the connected peripherals accept the provided voltage. Use manufacturer drivers for your OS to ensure stable operation and consult system logs or device manager entries to troubleshoot port recognition or conflicts.

## 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 |
|---|---|
| Compliance 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 PCIe 4-port RS232 Serial Card StarTech PEX4S953 cost, and is it available for purchase?

The price is 148.49 € (valid at the time of publication and already includes all taxes). The item is available for order — 7 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 10.07.2026 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, Bank cards on-line, Apple Pay, Google Pay, Installment. All transactions are 100% secure and encrypted.

### Can PCIe 4-port RS232 Serial Card StarTech PEX4S953 be purchased with a lease?

Yes, the purchase is available both on credit and with an interest-free installment plan. Learn more about installments and credit options: https://aio.lv/en/payment#b3

### 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 PCIe 4-port RS232 Serial Card StarTech PEX4S953?

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/3455913/64216371_large.webp