Can anyone inform what I need , to connect my 1992 Mazda MX6 V6 OBD to a Laptop via the RS232c socket (ie RS232c pins for input voltage od 12V).

I know that on the car there is a Bat +12v socket and one marked FEN, by placing a 12v led between these, the LED flashes the codes. It must be possible to transfer the intermittant voltages to the RS232. However I don't know the maximum voltage input for the common RS232c, will I need to reduce the voltage by resistors?

I would like to create a VB program to display the codes on the laptop.