GRT Avionics

I am just hooking up the elevator trim position sensor and saw this on Vans Forum

2. Nowhere is it mentioned that the HX analog inputs have software-selectable pull down resistors. No need to run power supply wires to flap position sensors, etc

Is there more detail available?

Thanks,

Rocky Morrison

That was my post. If you are using a Ray Allen servo/position sensor, the sensor has 3 wires - one from each end of a rheostat, and one (I think it is green) from the variable slider tap. You can do the following: in either case hook up the green variable slider tap wire to one of your HX's analog inputs. Connect one of the wires from one end of the rheostat to ground. Then (option one) do no more wiring. In the setup menu for that analog port select "pull down on" or whatever the exact words are. Or (option two) connect the other rheostat wire to the regulated 5 volts from your EIS, and in the HX menu select "pull down off".
In either case, you can then power up, fill in the table of volts vs position for display as you run the trim over its full range.

Note (GRT confirm?): it appears the pull down set up uses unregulated buss power, I see slightly different indications with the alternator on, versus off.

Bob & ZuluZephyr,

In response to this and the VAF thread, I just uploaded new Trim/Flap sensor wiring diagrams for HX/HXr and HS/WS. They are located here: http://grtavionics.com/manualsmodules.html The HX/HXr wiring diagram is the same but there is a new note about the internal pull-down resistors.

Bob, I don't know enough to answer your question about unregulated buss power-- maybe Jeff can answer this one. Thanks for the questions!

Hi Katie,

Perfect and just in time. Bob I am using the regulated power line.

Thanks,

Rocky