Rx Tx and External Power Supply Problem with Arduino Due

Hello everyone.

I am using Arduino Due to send number to computer over RS485 and USB. Sending is not an issue with USB cable plugged in. When i unplugg the USB cable and use power supply 9.0V, rx,tx are not working. I am using Rx as pin 0 and Tx as pin 1. I tried almost everyting, using resistors, capacitors, disabling AutoReset but they did not work for me. I do not know why but the maybe the Arduino Due works different from other boards.

Anny Suggestion ?

Thank you Best Regards.

Use one of the other serial ports - the Due has 4, and you're using the one that is connected to the USB Serial adapter.

The non-connected serial adapter dangling off those pins is preventing it from functioning I suspect.