/opt/openhab2/send_cul.sh

 #!/bin/bash 
 debug=0 
 pipe=/opt/openhab2/send_cul.fifo 
 cul="/dev/ttyCUL0" 
 function clean_up { 
 # Perform program exit housekeeping 
 rm $pipe exit $1 
 } 
 trap clean_up SIGHUP SIGINT SIGTERM 
 stty -F $cul raw ispeed 38400 ospeed 38400 cs8 -ignpar -cstopb -echo (cat < $cul )& 
 mkfifo -m 666 "$pipe" 
 while true; 
 do 
 while IFS= read -r cmd; 
 do IFS=\ read address ohcommand <<< $cmd 
 if [ -n "${ohcommand}" -a -n "${address}" ] 
 [[ debug -eq 1 ]] && echo got message: $ohcommand $address 
 then 
 if [[ x"${ohcommand}" = "xON" ]] then 
     [[ debug -eq 1 ]] && echo F"${address}"10 to $cul 
     echo F"${address}"10 > $cul 
 elif [[ x"${ohcommand}" = "xOFF" ]] then 
     [[ debug -eq 1 ]] && echo F"${address}"00 to $cul 
     echo F"${address}"00 > $cul 
 fi 
 fi 
 sleep 0.2 done < "$pipe" 
 done 
 clean_up

item configuration

Switch WallSwitch4 "Steckdose4" (gLicht) {exec="*:/bin/sh@@-c@@echo CCCC04 %2$s >> /opt/openhab2/send_cul.fifo"}

/opt/openhab2/start.sh

!/bin/sh (/opt/openhab2/send_cul.sh)& [...]

/etc/udev/rules.d/cul.rules

ATTRS{idVendor}"1a86", ATTRS{idProduct}"7523" SYMLINK+="ttyCUL0" MODE="0666"