HX Analog Input Sharing? What to wire to EFIS 2 as well?

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hplevyak
Posts: 36
Joined: Tue Mar 12, 2013 1:52 pm

HX Analog Input Sharing? What to wire to EFIS 2 as well?

Post by hplevyak »

Guys,
In the Installation manual (Rev A, Feb 2009) page 9-1 it states that an HX will share all inputs with another HX over the Ethernet link, including Weather.

Right now I'm using a number of Analog inputs for my EFIS HX #1 and have wired them to the "B" connector. I have NOT wired any to the EFIS HX #2 "B" Connector.

Is it better practice to also wire the analog inputs directly to the 2nd EFIS "B" connector as well?

I'm considering the case where EFIS #1 has a display failure. I'm assuming the ethernet link would still work and if needed, I'd be able to see those analog inputs on display #2.

What are folks doing in this scenario?

Thanks for your guidance here.

Howard (final finishing of EFIS wiring)
Bobturner
Posts: 444
Joined: Mon Mar 11, 2013 6:34 pm

Re: HX Analog Input Sharing? What to wire to EFIS 2 as well

Post by Bobturner »

I only wired analog inputs to one DU, because I have nothing critical there. I can always look outside to see the flap position! If you choose to wire to both for redundancy, then you will also need to furnish an external bias resistor for a resistive sender. If you use the internal pull up resistors, the calibration will be off if one unit fails. (depending, of course, on the exact failure mode.)
hplevyak
Posts: 36
Joined: Tue Mar 12, 2013 1:52 pm

Re: HX Analog Input Sharing? What to wire to EFIS 2 as well

Post by hplevyak »

Thanks Bob. I don't have any critical inputs either...so looks like I'll only wire them to EFIS #1.

Howard
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