StarTech.com 4 Port PCIe Serial Adapter Card with 16550

Elevate legacy device connectivity with four independent RS-232 serial ports brought to life through a single PCIe expansion card. The PEX4S553 delivers robust, reliable serial communication by leveraging a native PCI Express design and four 16550 UART engines, making it an ideal upgrade for workstations, industrial PCs, and control systems that rely on dependable RS-232 interfaces. With one PCIe slot, you can consolidate multiple serial connections into a compact, cost-efficient solution without sacrificing performance or compatibility. Whether you’re integrating POS peripherals, CNC controllers, test equipment, or industrial automation devices, this 4-port adapter is designed to simplify your setup while preserving the signal integrity and stability that RS-232 serial communication demands.

• 4 RS-232 ports in one PCIe card: Expand your system with four full-featured RS-232 serial channels (DB9 connectors) from a single PCI Express slot. Each port operates independently, enabling you to connect multiple devices such as barcode scanners, POS terminals, PLCs, GPS receivers, modems, and other legacy equipment without contention. This consolidated solution reduces clutter and frees up valuable motherboard I/O while ensuring reliable, discrete serial paths for each device. The versatility of four ports makes it an excellent fit for laboratories, data centers, manufacturing floors, and field-deployable systems where serial communication remains a cornerstone of operations.
• Native PCIe design for high performance and reliability: The PEX4S553 employs a native PCI Express architecture that communicates directly with the system bus, minimizing latency and CPU overhead. By avoiding bridging or emulation layers, this card delivers predictable timing and stable operation for time-sensitive applications such as instrument control, real-time data logging, and synchronous serial workflows. This design also helps reduce IRQ sharing conflicts and improves system responsiveness, making it well-suited for high-demand environments where consistent serial throughput is essential for mission-critical processes.
• 16550 UART per port for robust serial communication: Each of the four RS-232 ports is backed by a 16550-compatible UART engine with per-port FIFOs, enabling smooth data bursts and reduced risk of data loss in noisy environments. The 16-byte FIFO per port minimizes interrupts and keeps CPU utilization low, while standard RS-232 signaling ensures broad compatibility with a wide range of devices and software. This architecture supports reliable command-and-control, telemetry, and data transfer across multiple serial devices at steady, predictable performance, making it a dependable backbone for industrial automation, research labs, and enterprise applications.
• Broad OS compatibility with straightforward driver support: StarTech provides driver options and setup utilities designed to accelerate deployment across common operating systems. Windows users typically experience quick, plug-and-play recognition, with drivers that integrate smoothly into existing port configurations. Linux environments are supported through vendor-provided drivers that enable seamless enumeration of the four COM ports and straightforward port configuration. The DB9 connectors maintain compatibility with countless serial devices and legacy software, ensuring you can configure and test ports with familiar tools without extensive reconfiguration.
• Versatile, scalable serial expansion for industrial and legacy devices: Whether you’re integrating CNC machines, PLCs, POS peripherals, network equipment with console ports, or other RS-232-based devices, this 4-port PCIe card provides a scalable, future-proofed expansion path. It preserves essential RS-232 interfaces while leveraging modern PCIe performance, enabling you to consolidate devices into a single expansion card and simplify cabling, inventory, and maintenance. The result is a cleaner workspace, easier asset management, and improved reliability for demanding environments such as manufacturing floors, laboratories, and data centers.

Technical Details of StarTech.com 4 Port PCIe Serial Adapter Card with 16550

• Model: PEX4S553
• Ports: 4 x RS-232 serial ports (DB9)
• Interface: PCI Express (PCIe) expansion card
• UART: 16550-compatible per-port serial controllers (4 total)
• Bus Power: Powered by PCIe slot; no external power connector required
• Form Factor: Standard PCIe expansion card
• FIFO: 16-byte per-port FIFO for efficient data handling
• Operating System Compatibility: Drivers available for Windows and Linux (check StarTech for latest support)

How to Install StarTech.com 4 Port PCIe Serial Adapter Card with 16550

• Power down your computer, unplug the power cord, and remove the side panel to access the motherboard and expansion slots.
• Identify a vacant PCI Express slot (preferably PCIe x1) on the motherboard. Remove the corresponding screw from the chassis standoff area to secure the card later.
• Ground yourself to prevent static discharge, then align the card with the slot and firmly insert it until it seats fully. Attach the bracket to the case with the screw to secure the card in place.
• Reconnect power and boot the system. If the operating system detects the device automatically, you may be prompted to install drivers from StarTech’s website or your OS installation media.
• Install the appropriate StarTech drivers. Visit the StarTech support site to download the latest Windows and Linux drivers, or use the drivers supplied with the card. Follow the on-screen prompts to complete installation and reboot if required.
• After booting, connect your RS-232 devices to the four DB9 ports on the card’s bracket. Use your operating system’s device manager (Windows) or a serial port utility (Linux) to verify port assignments (e.g., COM1–COM4) and ensure each port becomes available to applications.
• Open your terminal or application and test each port with a loopback or by communicating with connected peripherals. Adjust baud rates, parity, and flow control as needed to match device specifications and ensure reliable data exchange.

Frequently asked questions

• Q: How many RS-232 ports does this card provide? A: Four independent RS-232 serial ports accessible via a single PCIe card, suitable for connecting multiple serial devices simultaneously.
• Q: What PCIe slot type is required? A: A single-lane PCI Express slot (PCIe x1) is sufficient for operation and performance.
• Q: Are external power connectors required? A: No. The card is powered directly from the PCIe slot, eliminating the need for additional power cables in typical desktop deployments.
• Q: Which operating systems are supported? A: The card ships with drivers for Windows and Linux. For the latest compatibility and installation instructions, consult StarTech’s support site.
• Q: What kinds of devices can connect via these ports? A: A broad range of RS-232 peripherals, including POS terminals, CNC controllers, PLCs, modems, instrument panels, GPS receivers, barcode scanners, and other legacy devices requiring RS-232 communication.