Ok. In that case you need to find the port number that the pc has issued the serial cable. It will be com1 com2 etc and you'll need to set that in the Intravention downloader software. Think of this as the door number in a street. Get it wrong and the software is talking to the wrong place. Look in device manager and you'll see com ports In the list. You can expand the list and see any installed
The other thing is if you see gibberish on the screen, then the settings of the com port are probably wrong. You can check these by right clicking on the com port, click properties and then you'll see speed etc. the safest best is 9600bps, no parity, 8 bits
If you're lost, I'll take some screenshots from my laptop and post them up later on. I'm on Tapatalk right now