Just installed Domoticz on my spare Windows laptop and...

Cable works just fine in Domoticz. Perfect readings...

So why not on the Pi3?

Well I made a cable as described at https://www.domoticz.com/forum/viewtopic.php?f=14&t=4970&hilit=p1+cable . After some fiddling I got the cable working in puTTY. After that I tried to install the cable on my Pi3. But after: sudo cu -l /dev/ttyUSB0 -s 9600 --parity=none I got this message: Line in ...

Found the solution? I'm experiencing exactly the same. Although I had to set te permissions for ttyUSB0 first, but now 'sudo cu -l /dev/ttyUSB0 -s 9600 --parity=none' gives me the right information, just does't show in Domoticz. Output: Connected. /XMX5XMXABCD100003654 0-0:96.1.1 ...