For returns, the following is listed: "Support can be contacted through email at
rma@plxdevices.com or phone at 408-745-7591." Maybe the RMA department can transfer you to the department you need.
You may be able to find more contact info in some of the media downloads at
Media - PLX Devices Inc - USA
And here's their address:
PLX Devices Inc
440 Oakmead Parkway
Sunnyvale, CA 94085
Good luck