Help With Westerboer VW 921 Needed

Is there anyone out there who is intimately familiar with a VW 921 flight
computer? If willing, would you please contact me directly? I am trying to get
a CAI Model 20 GPS to communicate to a VW 921, but have been unsuccessful. I
have had someone double-check the cable for correct design and continuity. All
appears well with the cable. The GPS also seems to be working properly.

The VW 921 was returned to the factory this past summer for software and
hardware upgrades, and was pronounced to be in good working order.

I am hopeful that there is some little trick or setting I am not aware of. I
have also contacted the Westerboer factory. They suggested a couple of things,
but nothing helped. I want to be certain that the problem is in the 921 before
I send it back to Germany.

I also was wondering where I could find the pin-out specs on the DB9 connector
on the Model 20? Is that listed on a website somewhere?

Thanks in advance for any help (useful help appreciated even more).

Chuck