RS-232 Communications Adapters
Written by Michael Cone
Updated at January 29th, 2026
Many USB to serial adapters have incomplete or incorrect RS-232 implementations. There are many that we have tested and have found to be defective.
The Keyspan (below) is the only USB to RS-232 device we recommend for adding single serial ports to your computer.
MOXA makes devices that are usually very good. The multi-port unit is shown below.
Tripp-Lite Keyspan - USB to Serial Port Adapter
| The brand that we know works well is the Tripp-Lite Keyspan. We've fully tested this device in a variety of situations and have found that it handles all the important RS-232 lines. https://www.tripplite.com/keyspan-high-speed-usb-to-serial-adapter~USA19HS/ |
|
MOXA UPORT - USB to Multiple Serial Ports Adapter
| In the MOXA Uport line, you can purchase units that go up to 16 ports through a single USB port. https://www.moxa.com/product/UPort_1610-16.htm |
 |