Hi,
Thank you very much for the solution @hek: this sounds pretty straightforward ;-) and was what I was looking for.
I will check it out this weekend.
It would be fantastic to switch the hole system to mysensors! Since a lot of developing is already done.

I will come back to post my results.

Best regards
Crty

Hi,
Trank you all for your support. I got in running finally.
I reassembled the complete thing on the breadboard. Then I connected the wires directly (rx-tx and tx-rx). After changing the position of the inclusion of mysensors.h for some times and using the standard pins and the preset node id it worked.
Then I went further to test software serial lib which worked great. Then I extended the model to use the rs485 and after some adaptation of the wires (it's always the wires after some frustrating nights) it worked.
For understanding I integrated also two led to signaling the sending via the de pin. This helped a lot.
As this was working correctly I turned up the speed. Ok, 250.000 bps were too much, but 115.200 were running without any complaints. On a breadboard though but without any cable adaption or resistor as final terminator.
So for this topic we can conclude that if rs485 is not even running on 9600 bps on a breadboard, it's not because of the cable or the terminating resistors. In this setting it should work anyway. Unless you have no bug somewhere else....
So for all my followers again thank you very much. I can only suggest to myself to reassemble the test unit completely to rule out any wrong connections....
Bye kduino

Hi, I've cut present, setup and loop not to waist to much space. I edit and add them too...
Unfortunately as you can see, the gateway is not receiving anything and therefore not answering the node.
I will test with different hardware now, if there is something weird.

Wow cool, so the hardware is basically running, but for some reason, the gateway doesn't accept the message.
I'll double-check the signing algorithm (perhaps I comment it to see, if there are arriving unsigned messages) and I will post the result.
Strange thing. Thank you very much!
I'll do this tonight.