At first my english could be much better, but I'm sorry, it isnt.
If got a problem with the communication between a commerciel software on my computer and an Arduino Mega ( Clone).
ports of mega: Serial is connectet to computer for the debugging messages of the Nextion TFT. Serial1 is connected to the Nextion Display, Serial2 is connected to a UNO (RX- RX / TX-TX reset Pin to Ground) and with USB cable to the computer Serial3 is connectet to a USB TTL adapter (RX-TX/ TX-RX) stuck in my computer.
the software on my computer transmits and recieves strings to Serial2 and other strings to Serial3.
In this constellation everything works fine.
Now I want to change the UNO to another USB TTL adapter. I tried different one with multiple chips on. At least I diceded to take the one with the CH340 wich would be the same as the UNO. But the communication between the software and the mega does not work. The adapter works fine (tested with a bridge on RX TX and the Arduino serial monitor).
Now my question:
what could be the difference in the behavior of the UNO (used as adapter) and the USB TTL adapter? Why does the software accept the uno, but not the adapter?
I checked everything twenty times. There must be a little difference I didnt know. Could it be something with the reset pin on the uno. How can I transmit this behavior to the adapter?
Thanks a lot.