does sending commands via telnet have any effects to the receiver? Can you for example turn it on/off manually via telnet?
/bin/echo -ne PO\\r | nc -w1 $IP $PORT | head -n 1
For more detailled logging information, please set the loglevel of the binding to debug by adding this to your configuration/logback.xml:
<logger name="org.openhab.binding.pioneeravr" level="DEBUG" />
And post the output from startup.
From time to time my VSX-921 simply hangs up and won't accept commands either. Then power cycling the hole thing (really pulling out the power cord, normal standby is not sufficient) is the only way to get it back working. Happens once a month or so with my AVR.
Regard,
Rainer