Scrambled console on RPi3

[Rodney W. Grimes]

> A few minutes ago I unplugged and replugged a PL2303 serial adapter in an
> RPi3 running r329495. The serial console announced the disconnection with
> ugen0.4: <vendor 0x067b product 0x2303> at usbus0 (disconnected)
> uplcom0: at uhub1, port 2, addr 4 (disconnected)
> uplcom0: detached
> 
> followed by  a torrent of unprintable garbage. Then it calmly announced
> 
> <vendor 0x067b product 0x2303> at usbus0
> uplcom0 on uhub1
> uplcom0: <vendor 0x067b product 0x2303, class 0/0, rev 1.10/4.00, addr 4> on usbus0
> 
> The displaying host is a Pi3 running the latest Raspbian. It's not clear
> how much, if any, of the oddity is an artifact of the display. Experience
> to date suggests none.
>  
> Far as I can tell the pl2303 and the host RPi3 are working normally. I've 
> never done this experiment before on a Pi3, but have done it many times on
> a Pi2 and nothing of the sort has happened.
> 
> Hope this is of interest to someone...

Do you have which 4 wires connected?
Gnd - should be connected
TX - should be connected
RX - should be connected
Vcc - Do not connect this wire, doing so can lead to odd behavior
      unless you happen to be powering the device this way, and
      in your case, the RPi3 has a higher load current than USB
      can normally supply.

-- 
Rod Grimes                                                 rgrimes at freebsd.org