Also, refer to the HS34 FAQ.
Wiring and Compatibility Information
Garmin 430/530 Wiring: Serial, ARINC-429, and Analog confirmed to work.
Garmin SL-30 Wiring: Serial confirmed to work.
Garmin X96 Wiring: Serial confirmed to work.
250XL Wiring: Compatibility unconfirmed.
Articles initially adapted from [this thread]
May want to add some info from: http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1183734073/0#14