Hi Jimmy,
The maximum baud rate for my build-in serial port is 128000 b/s, if the file is 500MB = 500 * 1048576 = 5.24E8 Bytes. Suppose we are using the max baud rate, this transfer will take at least 5.24E8/128000= 4096 seconds = 68 minutes. This is the time you will expect to wait for the transfer. Remember that your devices' baud rates might be different from mine.
So just set the timeout (through the Property Node) to a value of 75 minutes or something, sit tight and wait.
Also, just FYI, we do offer a serial card that has a max baud rate of 2MB/s, that will save you lots of time in applications like this. Hope this works out for you.
Tong