I have had a PC based system for a long time, but got away from using it. It is purchased based on the manufacturer. I think if you go to OBD2.com, you will see some of the less expensive PC based stuff. I'm sorry I don't remember the brand name.

I bought that system about 12 or 14 years ago, so it might be that there are some better systems available for an IPad.

Hope this helps.