pi@raspberrypi:~ $ rigctl -m 1020 -r /dev/ttyUSB0 -s 4800 -P RIG tand
I played with the rigctl stuff and was able to read the rig's frequency and make changes, so it seems to be communicating over the cable. Of course that was the case with Fldigi, so no surprise there. All I can think of is somehow Direwolf is having a permission problem. Either that, or some sort of group membership problem.
Ok.. I think you highlighted the issue here... "-s 4800"! In your first post in this thread, you stated your direwolf.conf has:
PTT RIG 1020 /dev/ttyUSB0
Notice you're not specifying a speed here as well as the fact that you CANNOT tell Direwolf what speed to use. Looking at the current Hamlib 3.3 stable release (uses RIG 120), the default speed for a Yaesu 817 is:
./rigctl -m 120 -L
. . .
serial_speed: "Serial port baud rate"
Default: 0, Value: 38400
Range: 300.0..115200.0, step 1.0
Hamlib defaults to 0 bps?! That doesn't see right. Will your above "rigctl" tests work without specifying the "-s 4800" parameter (which is the Yaesu FT817's default speed)? If not, that seems like a bug in Hamlib and this also highlights that Direwolf should be able to support any required Hamlib parameters.