VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 04-07-2018, 08:29 AM
TShort TShort is offline
 
Join Date: Jan 2005
Location: Indianapolis, IN (KUMP)
Posts: 784
Default G3X general purpose inputs

I am using several of the general purpose inputs on the G3X for various notifications.
I have used all of the discrete inputs.

I connected both aux fuel pumps (for the extended range tanks) to GP3 and GP4, configured as active hi since they are not controlled through a VPX switch. Based on other threads and discussion with G3X support, I added a resistor and connected the resistor to the ground for each GP pin. These inputs work fine, and generate the desired alert when the pump is switched on. My understanding is that these are "pull down" resistors.

I have an issue with the alert for the main (backup electric) fuel pump. It is controlled by the VPX, so I am configuring it as active low. I understand I need a pull up resistor for this application. I connected this to GP5, with the input to pin 31 and the resistor to pin 30 (POS 5 HI/+5V). For some reason, this doesn't work - the alert stays active all the time.

Do I need to run the pullup resistor to a different pin? The examples in the install manual show pin 50 (Figure 30-2.2), which looks like 12V instead of 5V.

If I need to use pin 50, can I have multiple active low inputs connected to the same pullup resistor?

For some reason this pull up / pull down / active hi/low stuff is the one thing in the install manual that has given me fits.

Thanks in advance for the help.
__________________
Thomas Short
KUMP - Indianapolis, IN
RV-10 N316JS bought / flying
RV-8 wings / fuse in progress ... still
N329TS (had it, lost it, looking for new number)
Reply With Quote
  #2  
Old 04-07-2018, 08:52 AM
g3xpert's Avatar
g3xpert g3xpert is offline
 
Join Date: Sep 2010
Location: Olathe, KS
Posts: 1,959
Post

Quote:
Originally Posted by TShort View Post
I am using several of the general purpose inputs on the G3X for various notifications.
I have used all of the discrete inputs.

I connected both aux fuel pumps (for the extended range tanks) to GP3 and GP4, configured as active hi since they are not controlled through a VPX switch. Based on other threads and discussion with G3X support, I added a resistor and connected the resistor to the ground for each GP pin. These inputs work fine, and generate the desired alert when the pump is switched on. My understanding is that these are "pull down" resistors.

I have an issue with the alert for the main (backup electric) fuel pump. It is controlled by the VPX, so I am configuring it as active low. I understand I need a pull up resistor for this application. I connected this to GP5, with the input to pin 31 and the resistor to pin 30 (POS 5 HI/+5V). For some reason, this doesn't work - the alert stays active all the time.

Do I need to run the pullup resistor to a different pin? The examples in the install manual show pin 50 (Figure 30-2.2), which looks like 12V instead of 5V.

If I need to use pin 50, can I have multiple active low inputs connected to the same pullup resistor?

For some reason this pull up / pull down / active hi/low stuff is the one thing in the install manual that has given me fits.

Thanks in advance for the help.
Hello Thomas,

To begin with, you might want to make sure you are using the latest (Rev. AE) G3X installation manual.

As shown on page 30-5, it does indeed sound like you have done the right thing to use GP5, pin 31 as an active low input, but we question whether or not this is really an active low signal.

You say this pump is controlled by the VPX. Does the VPX apply power to turn it on (active high), or apply ground to turn it on (active low)?

Thanks,
Steve
__________________
Garmin G3X Support
g3xpert@garmin.com
1-866-854-8433 - 7 to 7 Central Time M to F
Please email us for support instead of using Private Messaging due to the limitations of the latter.
Reply With Quote
  #3  
Old 04-07-2018, 09:00 AM
TShort TShort is offline
 
Join Date: Jan 2005
Location: Indianapolis, IN (KUMP)
Posts: 784
Default

The VPX switches are just to ground, no power, so it is active low.

I have the most recent revision (AE).

Thanks for the quick reply!
__________________
Thomas Short
KUMP - Indianapolis, IN
RV-10 N316JS bought / flying
RV-8 wings / fuse in progress ... still
N329TS (had it, lost it, looking for new number)
Reply With Quote
  #4  
Old 04-07-2018, 09:28 AM
TShort TShort is offline
 
Join Date: Jan 2005
Location: Indianapolis, IN (KUMP)
Posts: 784
Default

I should clarify the above.

For this pump, I am generating an alert (reminder) that the boost pump switch is on, not monitoring power to the pump itself (as I can do that with the VPX).

The VPX switch is just a ground, no power, hence this one is active low instead of active high like the two fuel pumps mentioned above.

Thanks
__________________
Thomas Short
KUMP - Indianapolis, IN
RV-10 N316JS bought / flying
RV-8 wings / fuse in progress ... still
N329TS (had it, lost it, looking for new number)
Reply With Quote
  #5  
Old 04-07-2018, 10:12 AM
g3xpert's Avatar
g3xpert g3xpert is offline
 
Join Date: Sep 2010
Location: Olathe, KS
Posts: 1,959
Post

Quote:
Originally Posted by TShort View Post
I should clarify the above.

For this pump, I am generating an alert (reminder) that the boost pump switch is on, not monitoring power to the pump itself (as I can do that with the VPX).

The VPX switch is just a ground, no power, hence this one is active low instead of active high like the two fuel pumps mentioned above.

Thanks
Hello Thomas,

We can do a better job of helping you if you email G3Xpert@garmin.com. We can ask for screen shots of your configuration, wiring sketch, etc.

For the GEA 24 discrete input to register as an active low signal, the voltage on that pin needs to be <3.5Vdc, and we suspect this is not happening when you activate the pump.

Thanks,
Steve
__________________
Garmin G3X Support
g3xpert@garmin.com
1-866-854-8433 - 7 to 7 Central Time M to F
Please email us for support instead of using Private Messaging due to the limitations of the latter.

Last edited by g3xpert : 04-07-2018 at 10:32 AM.
Reply With Quote
  #6  
Old 04-11-2018, 06:50 PM
TShort TShort is offline
 
Join Date: Jan 2005
Location: Indianapolis, IN (KUMP)
Posts: 784
Default

So the answer for those following along at home....

If you want to create an active low alert for one of the VPX switches (which just connect to ground), you need to either:

- use a DPST switch, and isolate the discrete or GP input from the VPX input

or

- use a diode to isolate the switch inputs from each other.

I chose option #1, since I had a switch laying around and I didn't want to cut into my wiring that was already in place for the VPX.

If you choose option #2, the diode is a 1N4005; thanks to Larry Bowen for giving me feedback on the process. He had success isolating both inputs with individual diodes.

Thanks to the G3X guys for the great support!
__________________
Thomas Short
KUMP - Indianapolis, IN
RV-10 N316JS bought / flying
RV-8 wings / fuse in progress ... still
N329TS (had it, lost it, looking for new number)
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 04:30 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.