Transmit image file thougth the TX TR serial line I have a digital camera with a USB port for image dowload from the camera SD card.

I will like to be able to capture this image files store in the camera SD card using the Arduino  TX TR lines (serial) then transmit this image file to the computer from the USB connection from Arduino to Computer. 

The reason need this scenario responds to that the camera dissables the shutter when sensing a USB cable conneted to computer. I do not knwo why this happens but I suspect is an underdeveloped feature of the camera.

Basically, I will like to use Arduino as a USB hub for external devices but at the same time to power down the line when no longer need the device using the Arduino TX and TX line . This will give tha camera a sense that the camera is been unplugged.







simulate this circuit &ndash; Schematic created using CircuitLab
You cannot. The TX and RX lines are UART. UART is not USB. USB is a very complicated protocol, and you need a proper understanding of how it works. It's not a simple serial protocol like UART.

Add to that the fact that the Arduino can in no way handle the amount of data involved in video, and you're already on a non-starter.