USB->Serial Adapter (high baud rate)


I recently bought the USB-Serial adapter based on the Prolific PL2303HX Chipset. According to the document, baud rates up to 12Mbps are possible, however nothing above 1Mbps comes across as a valid signal via the oscilloscope. How do you enable or utilize the higher speeds on this adapter? I need to use the adapter at 5Mbps.


Hi Raffael-

Thanks for writing about the challenges with your Prolific Chipset USB serial adapter.

We are aware of the speed limitations, and do our best to specify this as you can see on both our listing pages on Amazon and where we state:

“Programmable baud rate from 75bps to 12Mbps. 256 byte inbound and outbound buffers. Typical speeds 230 Kbps or greater”

I apologize that the speeds advertised by prolific set expectations that we haven’t found to be consistently achievable, and this is why we mention the 230K range as something more realistic. Achieving consistent 5mb speeds isn’t feasible in the real world- it might work in a chip to chip direct environment but in the real world interference and signal degradation make these speeds highly unreliable. Shorter cable runs between adapter and end device *might* help, but I just want to reinforce that the 230k range is where we’ve seen pretty consistent results.

Thanks again for contacting plugable support, we do make efforts to be transparent about the real-wold results using our products, and appreciate your time to detail the limitations you’ve found.

Please do let us know if we can be of any further assistance.

Best wishes-

Jeff Everett