[Solved] Home Assistant integration with Mysensors on RPi 3 and Arduino Mega - missing all entities

Welcome, perhaps someone has already encountered a problem like the one I am experiencing and can help me solve it.
I have Home Assistant installed on an RPi 3 and to this connected an Arduino Mega via USB with a sketch for 28 relays uploaded. I am using the Mysensors libraries. Theoretically everything should integrate automatically when I add the Mysensors integration, point to the port etc. And up to a certain point it is ok. HA sees the arduino, only that there should be 28 entities (relays), and in fact there is only one entity, and a fake one at that (some battery indicator which is not mentioned in my sketch). The fact is that the relays did show up for me, but after a long time and it was on the basis of the individual entities "flowing" over a period of about 24 hours. However, they never "flowed" more than 21 units. In the logs I have the info: WARNING (MainThread) [mysensors.sensor] child_id 1 already exists in children of node 0, cannot add child - and so on for each relay. I've used the same sketch and hardware before, only with Domoticz and it worked. What could be wrong?

It looks like you have a child_id name conflict, each relay should have a unique child_id. Not sure how it is defined in the Arduino and not sure what the mysensors configuration is, for example:



It is also possible to dump the persisence file, dump everything home assistant and add again.

I'll honestly admit that I'm a total novice in this area so why don't I paste my arduino code here, and below also the mysensors file that generates the Home Assistant. If you could take a look at it and direct me more precisely I would be very grateful.
Mega arduino code for 28 relays with buttons:
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I'm not that familiar with the solution, but throwing your code into GPT4, it recognised that you have a double call to the present() function with the same child_id. Same thing in the for loop.
Maybe remove the repeated call to present() and preferably look for another program.

Hello again, thanks for the suggestion. There was actually something wrong with my sketch. In the end, I looked for a completely new one and converted it to my needs and now it is ok. Thanks anyway. Best regards and topic closed.

New sketch for Arduino under the latest MySensors libraries. It works!