The picture here shows the configuration I have currently on Stella. The heading data from PG500 is received by the master MFD on data port 3. I have connected port 2 output to the Hydra to deliver GPS and heading data which is used by the Hydra. This last connection was made by me when my GP150 failed. My original installation by Amel/Pochon had the GP150 delivering GPS data to the Hydra, but no physical connection to deliver heading data. You will likely need to find a way to make this connection. Hope that makes sense!