Best Serial Port Cards Under $100 (2026)
We scored products by interface versatility, build and mounting options, UART specifications, power features, and overall value under $100
The Verdict
- Best Overall: HF2211 Serial Port Server: RS232/485/422 to Ethernet DTU — Best for networked serial devices: converts RS232/485/422 to Ethernet for remote DTU communication
- Best Value: 2-Port ISA Serial/Parallel Expansion Card — Best for vintage PC upgrades: two-port ISA expansion combining serial and parallel connectivity for legacy systems
This roundup covers serial port cards and converters priced under $100, focused on reliable RS232/RS485/RS422 connectivity, PCI/ISA/ethernet interfaces, and DIN-rail or PoE options. Selections emphasize value by balancing interface type, build quality, and practical features for industrial and legacy-device use
Top Picks
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1
Best Overall HF2211 Serial Port Server: RS232/485/422 to Ethernet DTU
Best for networked serial devices: converts RS232/485/422 to Ethernet for remote DTU communication
HF2211 converts RS232/485/422 serial interfaces to Ethernet for networked devices. Enables remote access and Ethernet DTU networking with multiple certifications for safety and compliance
- multi-interface serial support
- Ethernet DTU capability
- compliance certifications
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2
Best Value 2-Port ISA Serial/Parallel Expansion Card
Best for vintage PC upgrades: two-port ISA expansion combining serial and parallel connectivity for legacy systems
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
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3
USR-DR301 DIN-Rail RS232 to Ethernet Converter
Best for industrial panels: DIN-rail RS232-to-Ethernet device server suitable for cabinet-mounted equipment
DIN-rail RS232 to Ethernet device server with compact size. Enables remote serial access via Ethernet/Websocket. Customer note hints ease of use
- DIN-rail mounted
- RS232 to Ethernet
- Websocket capable
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4
RS232/485/422 to RJ45 Ethernet module with POE
Best for PoE deployments: RS232/485/422 to RJ45 module with power-over-Ethernet for remote installations
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
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5
StarTech 4 Port RS232 PCIe Serial Card with 16650 UART
Best for multiport PCIe setups: four RS232 ports with 16650 UARTs for reliable serial expansion in modern PCs
Four RS232 ports with high-speed data transfer, featuring 16650 UART and 256-byte FIFO. Includes 4x 30cm IDC to DB9 cables. Suitable for PCI Express systems
- four high speed rs232 ports
- 16650 uart performance
- includes serial cables