enable serial communication

i can enable serial communication. without connected usb to arduino mega??. i want use serial1 port!!!! when i connected the usb is working. but when i use a external power. the serial1 don't work!!!!

What are your trying to send Serial data to when you are not connected to the computer?

i what to connect xbee direct to arduino when a use the usb the serial1 send and received data and de wireless is working but when a change to external power dont work. the serial1 not send and received data.

Arrch: What are your trying to send Serial data to when you are not connected to the computer?

yes

What wires have you connected to what exactly? Are the ground wires connected?

leinadlopez:

Arrch: What are your trying to send Serial data to when you are not connected to the computer?

yes

That wasn't a yes/no question.

There's definitely something in the air tonight. He read your question as:

What, are you trying to send Serial data when you are not connected to the computer?

xbee arduino

rx > tx i use voltage dividers pin 18 tx > rx pin 19 3.3 v >3.3v gnd > gnd

PaulS:

leinadlopez:

Arrch: What are your trying to send Serial data to when you are not connected to the computer?

yes

That wasn't a yes/no question.

i trying to send Serial data for the serial 1 of mega without usb. is working with the usb the xbee is send and resieved data when i change to a external power don't send and resieved data

thanks i changed the arduino mega and is working but i found was the external power i don't know why. was a dc adapter 12v i changed to a battery 7.4 an is working

the external power i don't know why. was a dc adapter 12v

Wired correctly?