USB serial module strange behaviour

[tassheloff]

Hi all....
I've a pogoplug pro wifi used to monitoring a solar inverter .
What happen to me is that first serial command (/usr/local/bin/aurora -v -a2 /dev/ttyUSB0) returns
answer (as any other command i could give as i tryed) but second
command, whatever it is give bad error code 'cause receive -1 chars.
I've tryed on my Ubuntu PC and is all right.
Error is in pl2303 module i think that hangs up.... any solution? Have
had somebody my problem?
Thanks in advance