pl2303 (pl2303hx) serial ttl to usb converter review

Summary

If you have certain USB hubs between the pl2303 and the computer the connection stops working after a while.

If you have two USB hubs the connection may in certain cases stop working much quicker, and in other cases the connection will begin to work again.

The hubs / computer I have:

• USB 1 hub (with a Atmel at43301 chip)
• USB 2 hub (with a Genesys Logic GL850G chip)
• USB 3 hub (with a Genesys Logic GL3520 chip)
• Computer with USB 2 ports and one USB 3 port (Toshiba Satellite Pro r50 with Manjaro linux installed 2018)

The combinations I've tested:

• pl2303 - computer: OK.
• pl2303 - USB 1 hub - computer: OK.
• pl2303 - USB 2 hub - computer: Not OK: The connection stops working after about 5 minutes.
• pl2303 - USB 3 hub - computer (USB 2 port): Not OK: The connection stops working after about 2 minutes.
• pl2303 - USB 1 hub - USB 2 hub - computer: Not OK: The connection stops working after about 1 minute.
• pl2303 - USB 2 hub - USB 1 hub - computer: OK.

As a reference I have another usb-ttl converter (built in into the programmer of a Nucleo (development) board). It works at for all cases when the pl2303 fails.

The test

A byte is sent every tenth second (approx) from a development board (Nucleo-F411RE) towards the computer where I output the byte in a terminal window.

If the bytes are still arriving after 20 minutes, then assume that connection is working.

I used the computers USB 3 port all the time except one (see above)

Other

I also get an error message in the system log:

pl2303 ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32

This message comes two times with a few tens of seconds in between. After the first time the connection still works. After the second time the connection stops working.