Serial over 1 wire communication interface

So this is the issue...

Dive computers have the option to download all the data to your computer, but you will have to buy a 100 to 150 dollar cable(which in reality is just a virtual com port)..

my diving computer mares puck air has two terminals, so i wonder if it is serial where is the other teminal since i need 3...

one guy bought the expensive cable and took it appart and he draw the circuit

the software from the manufacturer mares reference to this chip CP210x USB to UART Bridge VCP Drivers

so i was wondering if this is correct, communicate just with 1 wire ( with the reverse diode) and ground via serial to the computer or an arduino?

is this a common practice?

I don't know if it's that common but it should work as far as I can see. There would have to be a pullup resister on DIO, that's probably internal to the puck.