I feel I'm nearly there. I found out that when I have mincom (the serial monitor) open and I run the commands
root@OpenWrt:~# echo 'SET MyDataDummyClass.Led_13 1' > /dev/ttyS1
root@OpenWrt:~# echo 'SET MyDataDummyClass.Led_13 0' > /dev/ttyS1
They are send to Arduino and Arduino responds and the output is set in minicom
SET started
name MyDataDummyClass.Led_13
Writable 1
Type Uint8_t
Value 1
SET done
SET started
name MyDataDummyClass.Led_13
Writable 1
Type Uint8_t
Value 0
SET done
So All I need now is a SEND URL where I can send my commands to. And a GET URL that can get me the Arduino values.
The SEND URL will take a param that is the actual command to send and echo the command to the serial port.
I need to think about the GET as getting value by value may impact performance.
I know for sure. If it is easy I'm not interested 8)
Best regards
Jantje