fs20 via https://github.com/Nidhoggrr/bulcs/tree/master/lights/modules/rfmsend

define rfmsendFnordlicht notify Fnordlicht "./rfmsend.sh 00 "$EVENT""
rfmsend.sh (visudo: fhem ALL=(ALL) NOPASSWD: /opt/fhem/rfmsend):

 #!/bin/bash
 if [ "$2" == "on" ] ; then 
 sudo ./rfmsend -a $1 -s 10 
 else if [ "$2" == "off" ] ; then 
 sudo ./rfmsend -a $1 -s 00 
 else sudo ./rfmsend -a $1 -s 12 
 fi 
 fi

fhem with TX868-75, 868 MHz module