different modbus frames between the native port and the Arduino

I wrote a program to establish a connection between the arduino due and my pc in modbus protocol via the native port.
With the native port I have the desired frame but when I established the usb connection via the programming port my frame is completely different.
I do not know the reason because it's the same program but I just replaced "SerialUSB with Serial"
please someone can help me?

Define “completely different”! Some example frames may help.

Post your program! (don’t forget to use code tags, that’s the </> button in the editor)

Post links to the used libraries (if they’re not part of the IDE).

thanks for answering but i have already solved the problem