Best Serial Port Cards Under $50 (2026)
We ranked items under $50 by interface versatility, build/form factor, networking features, power options, and a value score derived from specs and tag relevance
The Verdict
- Best Overall: HF2211 Serial Port Server: RS232/485/422 to Ethernet DTU — Best for networked serial: converts RS232/485/422 to Ethernet with DTU functionality for remote device integration
- Best Value: 2-Port ISA Serial/Parallel Expansion Card — Best for legacy PCs: two-port ISA expansion provides serial and parallel connectivity for older hardware environments
This roundup covers serial port cards and converters priced under $50, focusing on devices that add RS232/RS485/RS422 ports or convert serial to Ethernet for industrial and legacy I/O. Picks were selected by comparing interface support, form factor, build features (DIN-rail, PCIe, ISA), and overall value score from product specifications
Top Picks
-
1
Best Overall HF2211 Serial Port Server: RS232/485/422 to Ethernet DTU
Best for networked serial: converts RS232/485/422 to Ethernet with DTU functionality for remote device integration
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
-
2
Best Value 2-Port ISA Serial/Parallel Expansion Card
Best for legacy PCs: two-port ISA expansion provides serial and parallel connectivity for older hardware environments
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
-
3
USR-DR301 DIN-Rail RS232 to Ethernet Converter
Best for DIN-rail setups: a compact RS232-to-Ethernet device-server designed for industrial rack and control cabinet mounting
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
-
4
RS232/485/422 to RJ45 Ethernet module with POE
Best for PoE deployments: offers RS232/485/422 over RJ45 with Power-over-Ethernet to reduce cabling and external power needs
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
-
5
StarTech 4 Port RS232 PCIe Serial Card with 16650 UART
Best for multitasking hosts: four-port PCIe card with 16650 UARTs for improved buffering and reliable serial throughput
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