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G3X discrete pins

Guilhermepilot

Guilhermepilot

Well Known Member
hello,
who has an discrete pins working, like external master warning, it can be canceled by pressing enter on GDU370 or do I need to have an external press to cancel button?
 
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Hello Guilherme,

In the G3X system, the external master caution and master warning lamps are simply there to call attention to the on-screen CAS (Crew Alerting System) messages on the PFD display. You can acknowledge these by pressing the ENT key, or by touching the on-screen message if you have a G3X Touch system. When an alert is acknowledged, the corresponding master caution or master warning lamp will cease flashing.

- Matt
 
Thanks Steve, can I conect it with a 12v cable or is it digital? another questions is there a way to have an external low oil pressure light via those discrete pins?
 
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Guilherme,
The master warning and master caution lights can be set to be triggered by any of the inputs to the g3x (oil pressure, fuel pressure, fuel level, etc.). This is done in the setup menu. The g3x pulls the pin to ground, so the other side of the light requires power. There are limitations to the amount of current the pins are capable of, so check the install manual before selecting the light.
There is not currently a way to trigger a separate oil warning light. The easiest way to accomplish this is to purchase a separate oil transducer and hook up a completely independent oil warning light. This is what I did as a backup.
Don't confuse the 2 discrete outputs with the discrete inputs.....
 
I have been using them with the g3x with success. I think I measured them a while back and they were under 5 ma
 
Russ,
To clarify, I used LED bulbs, these light bases can also be used with an incandescent bulb, and I believe this may be how ACS sells them. If you use the incandescent T1 3/4 bulb, it is 1.1 watts, which is 80ma@14V. I just verified that the LED T1 3/4 bulb runs 7 to 14ma depending on the color of the led light. White is 14ma. These lights and bulbs can also be ordered from Newark Electronics the EAO P/N is 31-040.005.
http://www.newark.com/eao/51-040-005/lamp-indicator-incand-t-1-1-3/dp/30B4245
And the bulbs are here
http://www.newark.com/lamps_incandescent/bulb-size/t-1-3-4/pg/810033151
and Here
http://www.newark.com/eao/10-2j09-1069/led-bulb-midget-groove-white-t/dp/82K8967?ost=10-2J09.1069
 
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Is there a way to test the annunciators (G3X Touch System) without an alert currently active? Just want to make sure they're wired up properly.

Thanks,
Russ
 
You should have power going to one side of the annunciation and the other side goes to the G3X respective pin. To test the light, ground the pin going to the g3x. If you used LED lights, polarity matters. If it doesn't light you probably have the polarity reversed.
 
grayforge said:
Is there a way to test the annunciators (G3X Touch System) without an alert currently active? Just want to make sure they're wired up properly.
Click to expand...

Good evening Russ - if you power on your PFD1 display in config mode and select the GEA 24 from the system info page (the first config mode page) you should see a button to allow you to test the annunciator outputs.

- Matt
 
Thanks Bill, but I've already tested the annunciator lights by connecting them to a 12v power supply. I want to illuminate them via the G3X Touch/GEA 24 to make sure everything is set up correctly.

Matt, I found the button. Worked perfectly (see below). I searched the Installation and Pilot's manuals... did I miss it? Also, it'd be nice if there were a way to test them while not in configuration mode to make sure they still work, say during preflight. There are annunciator lights that you can push to test, but mine aren't that type.

Thanks!
Russ

DSC01558.JPG
 
G3X discrete voltage sense

Resurrecting... I have set up a discrete input to signal the activation of the fuel pump. A "sense" wire is hooked up to the +power circuit of the fuel pump, so when it is energized (pump switched on,) that wire supplies +12v to disc #2 pin. I have configured the CAS message to be a green "FUEL PUMP," and it is set up as "active high."

This setup works - halfway. When I engage the pump, the green FUEL PUMP message displays as desired. However, when I turn the pump off - and it is actually off - the message remains. I had hoped that the message would turn on and off with power applied/disconnected to/from the pump. Is it possible to use a discrete input in this manner, and if so, what have I done wrong?

C.
 
maus92 said:
I have set up a discrete input to signal the activation of the fuel pump. A "sense" wire is hooked up to the +power circuit of the fuel pump, so when it is energized (pump switched on,) that wire supplies +12v to disc #2 pin. I have configured the CAS message to be a green "FUEL PUMP," and it is set up as "active high."

This setup works - halfway. When I engage the pump, the green FUEL PUMP message displays as desired. However, when I turn the pump off - and it is actually off - the message remains. I had hoped that the message would turn on and off with power applied/disconnected to/from the pump. Is it possible to use a discrete input in this manner, and if so, what have I done wrong?

C.
Click to expand...

Hello C.,

When used in this manner, with an input signal that is switched between 12V and "floating", the GEA 24 discrete input Active High configuration may also be thought of as "Active When Not Grounded". That is to say, it's very common in the electronics world for "a voltage" and "wire not connected" to be treated the same, at least when talking about a high-impedance digital input.

One approach would be to use a pull-down resistor of around 10k ohms (the value is not critical) between the GEA 24 discrete input and ground. This will ensure the discrete input pin is really sitting at a low voltage when the fuel pump switch is off.

Another method would be to use a DPST switch for your fuel pump, with one pole being used to switch power to the fuel pump, and the other pole being used to ground a discrete input pin when the fuel pump is on. That's how I did it in my airplane. This method has the advantage of keeping the fuel pump and annunciator circuits completely separate.

- Matt
 
g3xpert said:
Hello C.,

When used in this manner, with an input signal that is switched between 12V and "floating", the GEA 24 discrete input Active High configuration may also be thought of as "Active When Not Grounded". That is to say, it's very common in the electronics world for "a voltage" and "wire not connected" to be treated the same, at least when talking about a high-impedance digital input.

One approach would be to use a pull-down resistor of around 10k ohms (the value is not critical) between the GEA 24 discrete input and ground. This will ensure the discrete input pin is really sitting at a low voltage when the fuel pump switch is off.

Another method would be to use a DPST switch for your fuel pump, with one pole being used to switch power to the fuel pump, and the other pole being used to ground a discrete input pin when the fuel pump is on. That's how I did it in my airplane. This method has the advantage of keeping the fuel pump and annunciator circuits completely separate.

- Matt
Click to expand...

Hey, thanks for the fast reply. I'm not an electronics wizard as you can tell. Anyway, I have the VP-X switching the FP, so I'm probably not going to go with option #2. I'm trying to wrap my head around option #1 and the concept of the pull down resistor, and how to wire it properly. Are you saying to wire a 10K ohm resistor from the same discrete input pin to ground in addition to the "sense" wire that runs from the pump +12v to the discrete pin?

Thx!
 
Time again for the annual resurrection of this thread.

I have the same setup as post 16, switching the boot pump with a stick switch and VP-X. But, instead sensing 12v at the pump, I'm trying to borrow the signal off of the wire between the stick switch and the VP-X (J2-6). The pump still switches on and off as it should, but the new BOOST PUMP annunciator on the G3X is on regardless of switch position. I'm using Discrete 3, active low, and it's always `active` when the system is powered up. Powered off, using the multi-meter, the circuit tests fine.

How do I make the annunciator accurately represent the stick switch position?

Thanks.
 
If I understand your question and your configuration. In essence you have the sense wire for the G3X connected directly to the VPX pin J2-6. As Matt explained in an earlier response, lacking a hard ground, or "low", a high impedance floating circuit is sometimes interpreted as a "high" (not ground). To correct this a pull-down resistor (10K or so) is sometimes added to assure a proper "low". It seems you have the opposite issue. The G3X is seeing the open circuit on pin J2-6 as a low, regardless of the switch position. One way to solve this would be to use a pull-up resistor on pin J2-6 to ensure it's pin is high when the switch is not pulling it low. Since I am not familiar with the design of the VPX, I am not sure this would be acceptable and not cause other issues. That is something you could take up with the VP tech support.

An alternative would be to connect the sense wire to the high side of the pump. This would accomplish two things. The first and most important is, your annunciation would truly indicate that power is present on the pump. The method you have chosen only indicates the switch position. You have no idea if the pump actually has power, the electronic breaker may be open.
Of course the second reason is that it would be easier to just connect a 10K resistor across the pump or from the VPX output pin to ground, and hook the sense wire to the output pin of the VPX. Set the G3X to sense high, and you are done.
 
Thanks Bill. If I get the "Uh, no. That's not gonna work." from Garmin, I'll do as you suggest.

The VP-X would sense and alert a pump fault, so that aspect of it is covered.
 
Garmin phone support suggests I test the voltage at the discrete 3 pin, and I'll do so as soon as I can.

He also said 0 - 3.5v is considered active lo and 8 - 36v is active hi. The thought is I'm seeing something in the middle on that input. To me, that circuit is binary -- grounded or not. Apparently it's not that simple.
 
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