This article covers StarTech.com シリアル 4ポート増設 PCI Expressインターフェースカード 4x RS232Cポート拡張用 PCIe x1接続ボード 16550 UART内蔵 PEX4S553.
Overview
StarTech.com’s PEX4S553 is a PCI Express x1 interface card that adds four independent RS-232C serial ports to any compatible desktop. It targets users who need to connect legacy industrial equipment, point-of-sale terminals, or scientific instruments to modern PCs that no longer include built-in COM ports. Each port supports data rates up to 128 Kbps and is backed by a 16550-compatible UART with 128-byte FIFO buffers for both transmit and receive, ensuring reliable communication without overwhelming the host CPU.
Connectivity & Compatibility
The card uses a PCIe x1 connector (rev. 1.1 compliant) and can be installed in any available PCIe slot — x4, x8, or x16. A low-profile bracket is included in the package, which makes it suitable for compact cases and rack-mount chassis. The standard full-height bracket is pre-installed, so it fits right into typical ATX towers out of the box. Driver support covers Windows, Linux, and macOS; most modern operating systems recognize the card automatically, while official drivers can be downloaded from StarTech’s support page if needed.
Product Info
The PEX4S553 has been available for years and remains in active production. On Japan the price hovers around ¥7,981 (tax included). The standard warranty is two years, and extended coverage may be available through manufacturer registration. Package contents: the card itself, a low-profile bracket, and a quick-install guide. In terms of market positioning, this is a niche entry-to-mid-range product — not for mainstream consumers, but indispensable for professionals who need to bridge old serial hardware with current computing platforms.
Best Use Cases
First and foremost, this card is for engineers and technicians in factories, labs, or broadcast facilities who rely on RS-232 to communicate with legacy test equipment, CNC machines, or industrial controllers. Adding four ports on one card lets them consolidate connections without occupying multiple expansion slots. Second, it suits hobbyists working on embedded development, amateur radio, or retro-computing projects — a dedicated serial port provides more reliable console access than USB adapters. For typical home or office use (connecting a serial mouse or printer), a simple USB-to-serial cable is cheaper and easier — this card is overkill for those scenarios.
