Don't have a serial port?

You need THIS USB CONVERTER:

Keyspan  # USA-19HS

That is the only one that works well with this system.
All of the other brands we have tested have worked poorly, or not at all.
Sitck with the Keyspan USA-19HS and you should not have any problems.
It is available from many retailers, worldwide.

Amazon usually has it for $30 or so:  Here
If the link does not work (due to Amazon changing the site), just
email support@obdtool.com and we can locate it for you.

To find out where else to buy Keyspan USA-19HS, see:
http://www.tripplite.com/en/products/check-prices.cfm?sSKU=USA-19HS

Please do not ask about ANY other adaptors.  We have tried all
of the cheap ones and they do not work with this system.

They can also be found on ebay.  Just make sure you get the right model #.
Unfortunately, we do not stock the Keyspan USA-19HS at this time.