Grand Rapids HARS/EIS OAT Connection

[R.P.Ping]

I know this post is very specific but it would be nice to get this job done instead of waiting to call GR on Monday.
I'm wiring up my EFIS/EIS and I find the installation manuals for both the AHRS computer and the EIS have an input for the OAT. Which one should I use? I would tend to think the HARS would have priority, maybe it doesn't make any difference since they are connected through a serial port? Also, do both EFIS serial out wires (green/white) connect to the same serial in wire (yellow/white) of the EIS?
Any information would be greatly appreciated.

Thanks

[f1rocket]

The OAT wire is connected to the EIS. Leave the EFIS OAT pin unconnected.

I don't have my EFIS documentation with me, but I do remember the green/black wire from the EIS to the the serial port called out for in the plans. I don't remember which wire it was because I pin extracted the duplicate wires like this to avoid another connector.

My wiring diagrams can be found on my website if you want to see how I connected things up.

[Ironflight]

I am not sure if I actually hooked up the serial link FROM the EFIS to the EIS - not sure if it does anything - but I know that you can't tie two outputs (out from each MDU) to a single input. The two signals will conflict, and you'll get garbage.

Paul

[f1rocket]

Yes, that's true.

Also, there is no serial connection FROM the display unit to the EIS, only the other way. The green/black output serial connection from the EIS should be connected to one of the serial inputs of the primary display (if you have two). The interdisplay serial connections on pins 23 and 25 will transfer the EIS data to the other display.