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Best Serial Port Cards Under $50 (2026)

We ranked entries under $50 by a value score combining supported serial standards, physical form factor relevance, network features (if any), and verified user ratings

This roundup identifies serial port cards and converters under $50 that deliver the most utility per dollar for interfacing RS-232/485/422 devices with PCs and Ethernet networks. Selections are based on connection types, physical form factor (PCI/ISA/DIN-rail/modules), protocol support and publicly reported user ratings to prioritize value

Top Picks

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    2-Port ISA Serial/Parallel Expansion Card

    2-Port ISA Serial/Parallel Expansion Card

    MOUDOAUER • ★ 3.7/5 • Budget

    Retro ISA interface card with 2 RS232 ports (COM1/COM2) and a 5V powered PCI-like adapter. Works in vintage systems with ISA slots; supports DB15 and pin header COM2. Customer says it works with printers

    • two RS232 ports
    • DB15 and pin header interfaces
    • requires only 5V power
    Check current price on Amazon →
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    RS232/485/422 to RJ45 Ethernet module with POE

    RS232/485/422 to RJ45 Ethernet module with POE

    waveshare • ★ 3.5/5 • Budget

    Industrial data gateway converting serial protocols to TCP/IP, supporting multi-function serial server and gateways. Useful for data acquisition and monitoring. Customer note: reliability is good, though documentation quality and setup ease are mixed

    • POE capable Ethernet module
    • bi-directional transparent transmission
    • serial to TCP/IP with multiple gateway features
    Check current price on Amazon →

Buying Guide

Match interface and protocol

Confirm whether your equipment needs RS-232, RS-485 or RS-422 and choose cards or converters that explicitly support those standards to avoid compatibility issues

Choose the correct form factor

Select between ISA/PCI expansion cards, DIN-rail device servers, or compact modules depending on whether you need a PC add-in, industrial mounting, or inline Ethernet conversion

Prefer Ethernet device servers for networked I/O

If you need remote serial access, pick a serial-to-Ethernet converter or DTU that supports TCP/IP device-server modes to simplify integration with existing networks

Check power and mounting requirements

Look for PoE support, DIN-rail compatibility, or standard PC power constraints so the card or module fits your installation and power delivery options

Review reported reliability and ratings

Use aggregate user ratings and reviews as indicators of consistent performance and firmware maturity, especially for converters handling protocol translations