Making your own EMS sensor definitons

[dynonsupport]

SkyView has the capability for customers to create their own sensor definitions for the EMS. This way we can "support" a huge variety of installs without needing to do custom software. For low volume sensors where Dynon can't justify doing work ourselves, a customer can make their own assuming they have data about the sensor.

You can find the documentation for the sensor.sfg file here:
http://wiki.dynonavionics.com/Making_your_own_sensor_definitions

 

[Ken_Kopp]

I'd like to have a fire detector in the engine compartment. Can I connect one of your CHT or EGT thermocouples to any of the spare type A EMS pins and then set an alarm at say 500 deg? Thanks!

Ken

 

[dynonsupport]

There's only one pin pair (27/28) that supports a thermocouple, but yep, you can do that without having to change anything in the sensor configuration files.

 

[flybuddy]

I have an RV with a tachometer transducer (product description here-http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1271983553-452-501&browse=ei&product=vans-tach

Can I attach the Skyview ems tach function wires to the transducer as oppossed to the mag P-leads??? thank you Tom

 

[dynonsupport]

Yes, you just use the normal higher voltage rpm inputs (either one of them) for this.

 

[tucsonphil]

Can I display the Flap Position from the IFC-1 (Intelligent Flap Controller) made by http://www.tcwtech.com/IFC-1-page.htm

If this simply a voltage output from the Controller to drive the SkyView Flap Position?

OR

Do I need the RayAllen flap position sensor?

Phil

 

[dynonsupport]

If it outputted a 0-5DC variable voltage with position information, that would work. But it doesn't look like it does, from their diagram.

 

[rgcrothers]

I have been studying the EMS file definition programming and need some help.

The latest sensor definition file has everything I need with the exception of one important gauge that I really want to include in my engine monitoring. The gauge is an air fuel ratio meter and gets it's signal from a wide band oxygen sensor in the exhaust, similar to EGTs which I use as back up to this gauge. The big difference is that this gauge puts out a voltage signal from 0 to 5 volts, 0 volts correlating to 7.35, and 5 volts correlating to 22.39.  It is linear in between. It is basically a volt meter that reads out in a slightly different scale equating the the air fuel ratio the engine is running on.

I understand that I will need to create a new definition and add it to the file that gets loaded onto the system, as you cannot just add a new definition to the system, you must add to the file and then load the new file onto the system. I am OK with that. If I can just get that one definition I can append it onto the file and load it and be good to go!

The file has pre defined sensor definitions for everything else I need, except this one that I need to have custom made...

I understand most of what is needed as far as characterizing the gauge but coming up with numbers to plug into the polynomial part is over my head. My attempts to get help from Dynon tech support were not successful. I am told they might be able to help me in late January. I guess this means they are way busy..

If someone could help me to write this one program I can handle adding it to the definition file and loading it into the system. Has any body out there figured this out and had any success with it? I understand they are working on a more user friendly method of creating sensor definition files, but in the mean time I could really use some programming help with this.

Anyone willing to help?
my email is rgcrothers@gmail.com

Thanks in advance!

Skyview system retrofit on RV7A with Subaru power. Getting rid of the old Blue Mountain system.

 

[skysailor]

Since you have the voltage numbers and a linear function, you should have all the information you need. I think they just recommend you put the information into a spreadsheet to determine the values you need to input. It looks like the example they give may cover your circumstance as long as you have an input that can handle the 22.39v at the top end.

 

[rgcrothers]

I am interested in learning how to get the calculations needed in a spreadsheet, and get the results needed. Can you tell me more?

At 0 volts, I want the gauge to read 7.35, at 5 volts, it should read 22.39, and linear in between. In practice I keep my air fuel ratio around 12 to 1 at high power to maybe 13.5 to 1 at low power settings.

Randall

 

[mmarien]

Since it is a linear conversion you may be able to use one of the level or position definitions and put the conversion in the EMS file as a user calibration. That way you wouldn't have to mess with the sensor*.sfg file.

Do a backup of your Skyview and then look for a file called *ems*.dfg. If you have done a fuel level or flap position calibration there should be a "user_cal={" section like this:

user_cal={
valid=1
name=FLAPS POSITION
num_points=4
point={
volts=2.49874
value=0
}
point={
volts=2.29713
value=10
}
point={
volts=2.06589
value=35
}
point={
volts=1.77456
value=70
}
}

In your case you only need two points:

user_cal={
valid=1
name=AIRFUEL POSITION
num_points=2
point={
volts=0.0
value=7.35
}
point={
volts=5.0
value=22.39
}
}

The AIRFUEL is the NAME of the pin and widget that appears on the screen. Create the pin ranges where ## is the pin connected the device to.

c37_p##={
valid=1
name=AIRFUEL
id=POSITION
alarm_type=OFF
range={
max_display=23
min_display=7
range1_valid=1
range1_top=23
range1_bot=18
range1_name=R1
range1_color=RED
range2_valid=1
range2_top=18
range2_bot=15
range2_name=R2
range2_color=YELLOW
range3_valid=1
range3_top=15
range3_bot=13
range3_name=R3
range3_color=GREEN
range4_valid=1
range4_top=13
range4_bot=11
range4_name=R4
range4_color=YELLOW
range5_valid=1
range5_top=11
range5_bot=7
range5_name=R5
range5_color=RED
}
}

Then create the widget in one of the screen layouts. I think you should be able to create the widget ranges and widget style with Skyview once you load this file back with the user calibration in it.

Worth a try.

 

[rgcrothers]

Thanks for the detailed reply. It sounds like I may need to wait until I have calibrated my fuel sendors or something to be able to use this method. I do appreciate you taking the time to help! I will make the backup like you suggest and look for that file to see what I find.

 

[mmarien]

Ok. You have my interest as I'm adding electronic fuel injection this winter and need an oxygen sensor to tune it so I did some reading. I believe the linear formula for 0 volts=7.35, 5 volts=22.39 is AFR = 3.008 x volts + 7.35 where 3.008 is the slope (X1) and 7.35 if the Y intercept (X0). So the sensor file is:

sensor={
     id=AIR FUEL RATIO
     function=POSITION
     pins=C37_P8 C37_P22 C37_P31
     name=AFR
     min_val=7.35
     max_val=22.39
     resolution=1
     round=0.1
     is_piecewise=0
     low_coeff={
           c_x4=0
           c_x3=0
           c_x2=0
           c_x1=3.008
           c_x0=7.35
           }
     low_resistance=NONE
     low2high_cross=0
     high_coeff={
           c_x4=0
           c_x3=0
           c_x2=0
           c_x1=0
           c_x0=0
           }
     high_resistance=NONE
     high2low_cross=0
     window=.2
     shift=3
     age=16
     }

The last three values are just copied from other sensors so I don't know if they will work. I'm not sure what function to use. It should be RATIO but there are only 7 allowed functions:

                + PRESSURE (PSI)
                + TEMPERATURE (F)
                + VOLTS (VOLTS)
                + AMPS (AMPS)
                + CONTACT (VOLTS)
                + LEVEL (VOLTS)
                + POSITION (VOLTS)

Using LEVEL will probably result in GALS as the unit so POSITION is probably a good choice as there are no units. I'm not sure what widgets can be used with POSITION. Next time I'm at the plane I'm going to use my flap position pin C37_P22 with this sensor and see what widgets it will allow. The voltage range for my flaps is 1.77456 to 2.49874 so with any luck the widget should read from 12.7 to 14.9

 

[rgcrothers]

Hey, now we are getting somewhere.  When I set up my Blue Mountain sensors I had to manually calibrate each one. The process was tedious and labor intensive but much much simpler than this. For the temp sensors I used water and then oil and physically measured the fluid temps and created a reference table that was used by the EFIS to display properly.

Thank You for putting this together. If I ever make the change back to a real airplane engine , I will also use EFI.  I know Robert from his Subaru days and suspect his product will be excellent. I am using Simple Digital Systems on the Sube and have been quite happy with it for around 200 hours of flight time. Easy to program and as the name implies, it is simple. I use the mixture control knob that will override the programming, using the AFR gauge as my guide.

It is important to have a good guard on the mixture knob...

 

[mmarien]

Thanks Randall. I'll keep that in mind when I install the mixture knob. I can see that it could be disaster to go lean with WOT. Maybe we can convince Dynon to interface with the SDS system the same way they did with VP-X and manage the SDS ECU from Skyview.

 

[mmarien]

I tried the AIR FUEL RATIO sensor defined above but it needs more work.

I loaded the file and in the EMS settings associated the AIR FUEL RATIO sensor with pin C37_22 which is my Ray Allen flaps potentiometer. On the debug page it shows information changing as I move the flaps up and down, When I select the sensor on one of the layout pages it crashes the system and Skyview restarts. Pin C37_22 reverts to the previous flap sensor.

The other problem is that the POSITION sensor only allows a couple of gauge styles. We need a generic sensor function without any units that will allow all types of gauge styles to be used.

 

[dynonsupport]

Position sensors assume they go through user calibration (like fuel levels, flaps, and trim do). You're probably better off to use "volts". This will read "AFR VOLTS" on the screen, but should work otherwise. Volts also gives you full access to all widget types.

We'll consider the addition of a more generic type that won't add Volts or PSI to the end of the label, but it's not a request we get very often so I can't promise a timeframe for that.

 

[rgcrothers]

All my temperature senders are Westach brand. In talking on the phone it was determined that the Carb Temp definition is a good match for these. In configuring the gauge I find that using carb temp is limited to 170 degrees as the top end of the range. If I edit the line in the definition that reads max_value 170 to a higher number, will the gauge then be configurable for various fluid temp gauges? I will use one for coolant, oil temp, PSRU temp, fuel temp, etc. I probably need a max value of around 260 F for some of these.

I do understand that if I edit one definition I will need to reload the entire file.

Also, I notice two different carb temp definitions in the file. Can you recommend which one to use, or does it matter in my case?

Thanks for help on this..

Bummer about having AFR read "AFR Volts", but at least it sounds like the hard work 'mmarien" did will work, can you confirm?

RV7A with Subaru power, tearing out the Blue Mountain stuff and changing to Skyview, thus the desire to utilize existing sensors. Some are in very tight quarters and larger models will not fit...

 

[dynonsupport]

We don't guarantee that the calibration constants in the file are valid beyond 170 degrees. When you make a polynomial, you need to give it a range where it's valid, and 170 is the top of that range. You'd need to know the resistances of the sender at higher temps and then run these against the polynomial to see how much error you get.

The two carb temp senders are totally different so we can't tell you which one would work right. 100468 is 10,000 ohms at 25C and 100413 is 3,000 ohms at 25C.

 

[rgcrothers]

I continue to try to learn how to get the needed information for creating a sensor definition from excel, but so far my limited education in this kind of math is keeping me from sucess. There is information on the web that gets me close, but I need help to know I am getting this right. In case someone knows how to do this in Excel, or elswhere, and is willing to get the needed information I will copy the data from the sensor below.

This data is from Westach thermistor temp sensors that have two wires each, which I need for proper grounding of the sensors as they get mounted to several different items like radiator, gearbox, engine block etc. I ground them all to the same location. The data below is from Westach. The column on the left is temperature in F, the column on the right is Ohms of resistance.

0 49500
-10 35500
0 25500
10 18700
20 13800
30 9800
40 7840
50 5970
60 4600
70 3570
80 2780
90 2190
100 1750
110 1400
120 1130
130 915
140 745
150 615
160 507
170 422
180 348
190 296
200 251
210 210
220 178
250 113
300 57
400 16

Thanks for any assistance! I have also sent this in via email to Dynon support. All I really need is the correct numbers to plug in for the values of c_x0 through c_x4. From that point I can edit an existing definition, (carb temp should work), then add this definition to the sensor definiton file, load it into the system and things should be good to go for configuring my five different temperature gauges.

For your interest, the temp gauges will be used on a Subaru engine in my RV7A. I have about 300 hours on it in various configurations. It has ben supercharged and turbocharged with super good performance but not so super reliability...  Currently it is normally aspirated with perhaps around 160 HP and good reliability. I intend to build up a turbo motor for it again and get it right this time... I monitor temps for coolant, gearbox, intake air, fuel, and oil. I also monitor 4 EGTs, Air Fuel Ratio, etc. No CHTs of course.

Thanks or any help
Randall