Capacitent fuel probe to Dynon HDX issues

[LouRubin]

Im trying to mate a capacitent fuel probes to a HDX screen. I understand the frequency has to be converted to voltage for Dynon to recognize it . I used a Red Avionics

EI converter previously called Princeton avionics. I changed to pin locations to 22 and 23 as stipulated in the manual. The sensor option was changed to capacitent probes as well.

I tried to do a calibration, however after the 2nd setpoint Dynon prompted me the voltage didnt increase enough to move to the next setpoint.It gave me the option to use the value and continue which i did.The graph showed the voltage did increase but only around .06 of a volt for each setpoint. I prompted to use the value and continue. i finnally filled the tank and hit the full button.
Dynon showed the setpoint voltages at empty at .5 volts to setpoint 8 at 1.68 volts.
Are the voltages and spreads to low for Dynon to recognize? If so how do i increase them?
The fuel gauge remained inop with a X through it

Empty .6 volts
Set point 2 1.38 volts
Setpoint 3 1.44 volts
Setpoint 4 1.49volts
Setpoint 5 1.54 volts
Setpoint 6 1.58 volts
Setpoint 7 1.62 volts
Setpoint 8 1.68 volts Full tank 37 gallons

 

[Rhino]

If you have current software versions installed, you shouldn't need the voltage converter when using general purpose pins 22 and 23, and that might be your problem. You can connect the sensors to the EMS directly, and set SETUP MENU > EMS SETUP > SENSOR INPUT MAPPING to specify capacitive sensors.

General purpose pins won't read anything higher than 5 volts, so the spread isn't your issue, or certainly not the only one. Also, if the total voltage applied to the enhanced pins is high enough, it may blank out widgets on your screen.

Were I you, my next step would be simply taking the converter out of the system and see if that fixes your problem. You might also try asking Marc Zeitlin about this. He uses capacitive sensors.

 

[LouRubin]

Ok Rhino I’ll try eliminating the converter . I assume I tap off of pin 18 of the EMS for 5 volts output directly to the center connector of the probe? As always I appreciate your help

 

[Rhino]

...I assume I tap off of pin 18 of the EMS for 5 volts output directly to the center connector of the probe?...

Yes.

 

[Marc_J._Zeitlin]

If you have current software versions installed, you shouldn't need the voltage converter ...

This is correct - no converter is necessary to use capacitance senders with the Dynon EMS unit. Just follow the manual's instructions for capacitance senders.

 

[jakej]

This is correct - no converter is necessary to use capacitance senders with the Dynon EMS unit. Just follow the manual's instructions for capacitance senders.

Thanks Mark. Just thought I add this to help others -There is 1 case where an Red Avionics converter is needed is when changing out from the VMS units (ie VM1000 or 800) as their CP10A converts the frequency output to capacitance (0 - 5 volt) usually required by Glass displays & gauges.

 

[LouRubin]

I’ve tried to hook up the capacitance probes with out the Red avionics converter however the voltage is constant at 4 volts when I add fuel. I’m pinned at 22 and 23 on the EMS
And I switched the settings to capacitance probes.These probes are in a Lancair ES 17 years old originally set up for a Blue Mountain Efis . I removed the old converters.

The voltage does increase with fuel added using the Red avionics converter. I get around .6 volts at empty and 2.6 at full. I’ve only done the left tank however the gauge is inop with a Cal icon however the ? mark icon is gone.The screen accepted the calibration data but it won’t show on any indication on the left fuel gauge

 

[chriscalandro]

That spread should be fine. When I did my Mooney the spread was even less than that and the tanks read perfectly.

 

[Dynon]

A couple of comments:

If your capacitance probe has a voltage output (ie, a variable voltage within 0-5V), the advice above holds: you can ditch the converter and use a GP input. If it's actually a frequency output though - which some are - you'll need a converter.

As for the voltage readings: Should be fine. SkyView warns when it sees a minimal voltage change from reading to reading. A few millivolts is pretty narrow, but if it's consistent, it will work just fine. It turns out a lot of the capacitance probes and converters convert to a pretty narrow voltage range.

 

[chriscalandro]

Is there any plan from Dynon to support frequency output?

Does anyone know if CIES makes a pipe mount probe? All I see is the 5 bolt senders.

I have the vision micro probes and I’d really like to not have a bunch of converters.

 

[Dynon]

There aren't currently plans to support frequency output.

 

[jakej]

Is there any plan from Dynon to support frequency output?

Does anyone know if CIES makes a pipe mount probe? All I see is the 5 bolt senders.

I have the vision micro probes and I’d really like to not have a bunch of converters.

You probably already know this - Red Avionics have the CP10A specifically for the VMS probes, I have bought 5 of them recently & they do work. The voltages are similar to what is in Post #1 above.
There are some difficulties setting it up as the instructions aren’t clear enough IMO - PM me if you want more info.
ps - the converters are very compact so don’t take up much space.