USB cable from the 6700 directly to a USB port on the Raspberry PI 3

Is there a question lurking in there somewhere?

As far as I know from Alpha you must use an FTDI approved chipset device.  I see where your going here, I think your gonna need a couple of serial interfaces, one for the flex and one for the Pi...  then interpret the data coming into the Pi via serial...  I think...

Mark, but maybe we can found a solution that Flex and PA can communicate via LAN. Then no need for a USB connection.

And still open question is: need a good Amp a interface connection to TRX - if PA always check the frequency , switch automatically Band and Auto Tune do his work alone .... 

.... mark please buy onother Raspi now - maybe it push FRS again for new things :-)

Back of the napkin function for discovery (haven't tested this but it should work)

#!/bin/python

import select, socket

def discoverRadios():
"discovery"
port = 4992 # Flex VITA-49 port
bufferSize = 1024

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind(('', port))
s.setblocking(0)

result = select.select([s],[],[])
msg = result[0][0].recv(bufferSize)

radio = dict(s.split('=',1) for s in msg.split(" "))
return radio

How you call it:

while radio is None :
radio = discoverRadios();

radio will be a dict object, for example if you want the radio's IP it will be:

print radio ['ip']

Similarly you can use tcp streams to get the per slice frequency.

Ria Edit: oops, looks like GS destroyed my indentation. Oh well, if you know python you can figure it out