Using Arduino Uno as USB to Serial UART Converter

Hi

I have a 4d µLCD-144(GFX) display, for which I would like to update the pmmc using the 4d PmmC Loader. This site recomends me to also buy a USB to Serial UART Converter, but can the arduino board not do the same if I remove the ATMEGA chip? It is an Arduino Uno I am trying to use.

I have tried to connect the two like this: Connected 5V from Arduino to VIN on the display. Connected GND from Arduino to Both GND on the display. Connected TX from Arduino to RX on the display in series with 1k Ohm. Connected RX from Arduino to TX on the display. Connected the Reset pin from Arduino to the RES on the display. I think the RES should be connected to DTR, but I don't know where this is on my arduino.

But when I try to load the new pmmc file the RX led just keeps flashing and the uploading nerver starts.

I come someone can give me some advice, thank you in advance.