Pitot heat to EMS 220

[BlueCH750]

I've got the Dynon heated Pitot/AOA and have configured the Pitot heat status line as a contact type sensor for display on the SV-D700 PFD. I am only seeing 5V on the pin and no variation as I cycle Pitot heat off and on when looking at the sensor debug page. Pitot heat functions as expected via switch position. What's going on? Open to thoughts and ideas from all! Thanks!

 

[BlueCH750]

OK, gathered a bit more info and testing, but could use some additional insight on how best to troubleshoot this issue.  Pitot heat works as expected i.e.; heats when switched on, and does not heat when switched off, inflight the amp draw increases and decreases as controller cycles Pitot heat. I have configured C37 P9 as a general contact type sensor, with a sensor configuration as shown in the installation manual under "Heated AOA/Pitot Status on EMS Page".  Pitot Heat and controller power is wired thru switch and ground is continuous run to firewall ground. White signal wire is directly to the EMS 220.  My problem is that the sensor debug page shows not variation in voltage as I toggle Pitot heat power switch...stays constant at approx 5V.  I expected voltage to vary to indicate the state of the Pitot heat status line (white wire).  Dynon or anybody who could give me a clue as to what might be going on?  The only thing I can think of is running a continuity check on the status line (white wire), but not sure how best to do that?
Thanks for reading my lengthy prose...appreciate any assist!

Dave (still loving my Dynon stuff and customer support!)

 

[Dynon101]

Dave,

I believe the pitot heat status line (white wire) is an GROUND or NO GROUND wire...in other words the voltage output does not modulate.

The PITOT HEAT STATUS line (White wire) is grounded when the controller is turned off or not
functioning properly. The PITOT HEAT STATUS line (White wire) can be connected to an
indicator on the panel, whose other terminal is connected to Switched 12V
When the Heated AOA/Pitot Probe is switched on and functioning properly, the PITOT HEAT STATUS line will be open (not grounded), leaving the indicator light turned off (no current is flowing). The PITOT HEAT STATUS line (White wire) can handle a maximum of 1A current, so choose the type of
indicator carefully.

Check out page 5-12 of the AOA/Pitot Probe and Heated AOA/Pitot Probe Installation Guide Rev. D FOR ADDITIONAL INFORMATION.

DID I READ YOUR QUESTION CORRECTLY?

 

[BlueCH750]

HomeBuilt

Thanks for the reply, I'm not sure how to ask the question differently to make it more clear.  But as I currently understand things, the Pitot Heat Status Indicator (white wire) configured as a contact switch per the SV install should respond as below when I toggle Pitot Heat switch off/on.

HEATED AOA/PITOT PROBE – PITOT HEAT STATUS INDICATOR CHECK (IF INSTALLED)

A simple test ensures that the Heated AOA/Pitot Probe PITOT HEAT STATUS Indicator is working:

Turn off the switch or circuit breaker powering the Heated AOA/Pitot Probe

o The PITOT HEAT STATUS indicator should illuminate
o If displaying PITOT HEAT STATUS on a Dynon Avionics EMS unit or SkyView EMS page, the indicator should be Red.

Maybe Dynon will chip in with some insight... :

Dave

 

[jakej]

Check out pages 15-1 , 15-2 of the Install Manual rev AB (accessory installation & configuration).  I think that's what you need [ch128521]

 

[BlueCH750]

Hi Jake, thanks for the reply...what you reference is what I used for my sensor setup and configuration. Is it your understanding that the status line (white wire) should vary in voltage as I toggle my pitot heat? Thanks! Dave

 

[airguy]

The status wire does not vary its output as the pitot heat cycles on and off. The status wire simply tells you if the pitot heat SYSTEM is active, or not.

 

[BlueCH750]

Airguy, agree!  But, if I switch off power to the pitot heat and controller ("the system") then I thought the state of the wire would indicate loss of power and toggle the contact switch as setup per the SV install instructions.  Otherwise, what cause the sensor to function as a contact switch, i.e.; change from green to red.  What should I be seeing on the sensor debug page?  Right now, I' not sure...I had assumed seeing a voltage change.  Maybe someone with a heated pitot and EMS 220 configured to monitor the status of the pitot heat /controller function could chime in!  Appreciate everyone's input so far.  We'll get it figured out and (I) will learn something from it, I'm sure! 

 

[Raymo]

If you have followed the instructions (15.1-15.2) and it still does not work, I would double-check the wiring to the EMS, confirming the pin number and wire color (brown/blue). If that is good, check continuity from end to end.

Next try a different input pin.

Also be sure you have done the configuration for each screen layout.

 

[BlueCH750]

Ray,  that was my plan on the next warmish day in the hangar... continuity and proper pin check!  Just wanted to be sure I wasn't being a bonehead before I started cutting heatshrink!   :'(

 

[Dynon]

So the white wire doesn't output voltage, but it does switch from open to ground. Because of the way that the EMS module is designed, in one state the EMS should measure 5V (when that line is open), and when in the other (grounded) it will read 0V.

 

[BlueCH750]

Thanks Dynon, will do some pin verification and continuity checks.  Will advise the forum what I discover!