The arduino usb to serial adapter

hi there
I purchased a arduino usb to serial adapter the other day to upload code to my uno and mega 2560 but i can not get this to work tho, i had been using a uno with out the atmega328 in it and that works fine, have i bought this on the right intense? or do i need to update the ATmega16U2 or something?

thanks Joe

Why do you need a USB to serial adapter to uploaded code to your Uno and Mega 2560, when the Uno and Mega 2560 both have one built in?

How do you have it wired? Any pictures to show us? Did you do the loop back test?

Why do you need a USB to serial adapter to uploaded code to your Uno and Mega 2560, when the Uno and Mega 2560 both have one built in?

there not on a arduino pcb

How do you have it wired?

TX - RX
RX - TX
EXT RESET - RESET
5V - 5V
GND - GND

Did you do the loop back test?

No what is this and how would i do it?

Thanks Joe

think i have figured it you need a 0.1uf in line of the reset pin, don't no by it is not on the PCB but o well

thanks Joe