Hi Thomas,
I solved the receiving problem as well. I wrote a python script which uses pyserial to read the information of the cul in an endless loop. If a specific code (e.g. i512345 = on) is written, the scripts updates the switch status by using the HA api. The script runs on startup of my raspberry.
Pro:
the serial port is already open, so you can simply send messages via echo to the cul (unix e.g. echo “is00FFFF0FFF0F” > /dev/ttyUSB0). This works in no time! You don’t have to open a serial port or use a pyhton script to send a command to the stick.
Con:
very basic implementation at the moment. If I want to include new switches in HA I have to implement them on the python script as well. But it’s working well so far 
If you need any further information. Let me know…