contact sensor config

[alpinestar]

Im fumbling with sensor configurations for two SV EMS contacts... one is for a alternator fail (plane power); I believe a fail condition pulls the lead to ground.

The second is an ignition warning, where a fail results in +12V to typically illuminate a warning light.

I'm confused on the logic of ranges and colors to get the results I'm needing. I THINK i have stumbled on the right config for the alternator but would like to really understand it.

Is a contact the appropriate sensor type for the ignition fail? I hope so, changing to a more capable pin would be a real bummer... wondering if a voltmeter capable pin would have been better; could I "fake" a resistive sensor into working (a "level" sensor?)

 

[Dynon]

Contact would work well for the ignition fail. You'll see 5V on the if the line is open (same as unconnected), and 0V if it's being pulled to ground. Set your ranges to something like 0-2 and 2-5 and you'll be fine there.

The non-voltmeter inputs can only measure up to 5V, so if you need something that can go higher (12V in your case), the voltage inputs are the way to go.

 

[vlittle]

You can't directly input to the EMS with a 12V signal.  The work around is to use a series diode (1N4148, 1N4007 etc.) to allow the signal to pull down the Dynon input, but not drive it high.  It will pulled up to 5V internally.

I've done this with signals that drive annunciator lamps to 12V as well as the Dynon input.

EMS                         SIGNAL

|           |\ |
|--------| \|-----------o
|           | /|
            |/ |

FMI, see this thread http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1346264116/2#2

Vern

 

[alpinestar]

thanks vern, that's exactly the type of work-around I was looking for. I swapped pins 2 & 9 in the Dsub body to use pin #2 (voltmeter 2) to pick up the 12V signal.... Then discovered that the ignition signal in fact goes to ground, not 12V on failure. so I reverted the pins and can use a contact in a "normal" configuration now. If only that were the only stupid mistake I've made lately!