This article covers StarTech.com RS232Cシリアルアダプターカード.

Overview

The StarTech.com PEX2S553 is a PCI Express x1 expansion card that adds two RS232C serial ports to a desktop PC or server. It is based on the ASIX MCS9922CV-AA controller with a 16950 UART, supporting bidirectional communication up to 921.6Kbps per port and a 128-byte FIFO buffer for reliable data transfer.
This card is positioned as an upgrade to the popular PEX2S552, and it is designed for environments where serial connectivity is still essential: POS terminals, PLCs, factory automation, scientific sensors, medical devices, scanners, and oscilloscopes. It ships with a standard bracket installed and includes two low-profile brackets, so it fits both standard and slim chassis without extra purchases.

Connectivity & Compatibility

The card uses a PCI Express x1 interface, so it works in any desktop or server with an available slot. On the external side, it provides two D-Sub 9-pin RS232C ports, each independently configurable.
Power options are set via pin 9: you can choose 12V, 5V, or no power, and each port can be configured separately. This flexibility is useful when connecting devices that require different power levels.
The card supports Windows and Linux. Driver installation is straightforward, and StarTech.com offers free unlimited technical support for the lifetime of the product, which is a strong safety net for IT professionals.

Product Info

The PEX2S553 is available from StarTech.com's official store and major retailers like online retailers. In the market, it sits in the mid-range tier of serial expansion cards, priced higher than basic consumer models but justified by the 16950 UART, independent power options, and low-profile support. It is built for reliability and flexibility, making it a solid choice for professional and industrial use.

Best Use Cases

  • Engineers in factories or labs who need to connect PLCs or measurement instruments to a PC: two ports allow simultaneous control of multiple devices, and the pin-9 power options match different equipment requirements.
  • IT staff upgrading PCs in POS or medical environments where long-term stability is critical: the proven chipset and lifetime support reduce downtime risks.
  • Users with slim or small-form-factor PCs who need serial ports: the included low-profile brackets make installation easy in tight chassis.

Product Disclosure (Amazon)

  • Manufacturer: StarTech.com(スターテック)
  • Seller: fuji.harmotech
  • Fulfilled by: fuji.harmotech
  • ASIN: B0041UJREA
  • Note: This article covers a manufacturer-made product based on Amazon listing details.