FSXA KEAS Variable

TooLowGear · 2 Jul 2009

I am trying to make a simple xml that will save an L: variable, no switches this time. I seem to be having difficulty and I am not sure why

Code:

0(&gt;A:AIRSPEED TRUE , KNOT)
if{ 
(A:AIRSPEED TRUE , KNOT) (A:AMBIENT DENSITY , SLUGS) 0.002378 / * sqrt (>L:KEAS , NUMBER) }

I also tried

Code:

(A:AIRSPEED TRUE , KNOT) != (L:KEAS , number)
if{ (A:AIRSPEED TRUE , KNOT) (A:AMBIENT DENSITY , SLUGS) 0.002378 / * sqrt (>L:KEAS , NUMBER) }

but I get a 0 value for L:KEAS.

Thanks in advance for any help.

Vitus · 2 Jul 2009

The first snippet don't work because you are trying to assign a value to a A:variable which is not possible.

The if-part of the second snippet is in the wrong order. Try:

Code:

(A:AIRSPEED TRUE , KNOT) (L:KEAS , number) !=
if{ 
  (A:AIRSPEED TRUE , KNOT) (A:AMBIENT DENSITY , SLUGS) 0.002378 / * sqrt (>L:KEAS , NUMBER) 
}

Regards
Vitus

TooLowGear · 3 Jul 2009

Using this code L:KEAS , NUMBER is still being returned as 0.

If I understand correctly, the gauge is instructing:

If (A:AIRSPEED TRUE, KNOT) is not equal to (L:KEAS , NUMBER) then

(L:KEAS , NUMBER) = sqrt((((A:AIRSPEED TRUE, KNOT)*(A:AMBIENT DENSITY , SLUGS))/0.002378)

Code:

<Gauge Name="keas">
   <Element>
      <Select>
         <Value> 
			(A:AIRSPEED TRUE , KNOT) (L:KEAS , NUMBER) !=
			if{ 
				(A:AIRSPEED TRUE , KNOT) (A:AMBIENT DENSITY , SLUGS) * 0.002378 / sqrt (&gt;L:KEAS , NUMBER)
			}
      </Value>
      </Select>
   </Element>
</Gauge>

I tried (A:AIRSPEED TRUE , KNOT) 0 >= . . .
and
(A:AIRSPEED TRUE , KNOT) 0 != . . .

but every time the L value always comes back 0

it should be (L:KEAS , NUMBER) = sqrt( ( ( (A:AIRSPEED TRUE , KNOT) * (A:AMBIENT DENSITY , SLUGS) ) / 0.002378 ) )

Even

Code:

			(A:AIRSPEED TRUE , KNOT) (L:KEAS , NUMBER) !=
			if{ 
				2 (&gt;L:KEAS , NUMBER)
			}

returns L:KEAS as 0. I am very lost

Vitus · 3 Jul 2009

I am not sure about that, but try lowercase for the units. I found that sometimes lowercase seems to be required for that. So for instance instead of:

Code:

(A:AIRSPEED TRUE , KNOT)

try:

Code:

(A:AIRSPEED TRUE , knots)

err... yes. knots with s!

But this is just a wild guess, I don't know if it will solve your problems. Check if the A:AIRSPEED TRUE variable returns a value != 0 in the first place.

Vitus

TooLowGear · 3 Jul 2009

Thanks! Tried that too. I am going to see if TAS returns a !=0

at 49.77 TAS, KEAS should be reading 40.92. but it is still 0.

Code:

(A:AIRSPEED TRUE , knots) 0 !=
if{ 
	(A:AIRSPEED TRUE , knots) (A:AMBIENT DENSITY , slugs) * 0.002378 / sqrt (&gt;L:MYAIRSPEED , number)
}

that makes according to the infix to postfix converter: (L:MYAIRSPEED , number) = sqrt( ( ( (A:AIRSPEED TRUE , knots) * (A:AMBIENT DENSITY , slugs) ) / 0.002378 ) );

Can someone else try running it. Maybe its somehow on my end?

I tested != 0

using

Code:

			(A:AIRSPEED TRUE , knots) 0 !=;
			if{ 
				1 (&gt;L:TAS , number)
			}

Result on black box was 0

i tried

Code:

			(A:AIRSPEED TRUE , knots) 20 &lt;
			if{ 
				1 (&gt;L:TAS , number)
			}

while not moving and TAS was 0 in black box

L:TAS was still reporting 0

Vitus · 3 Jul 2009

I didn't check your complex example but the last code snippet you posted. The result: the same. It didn't work. BUT if you delete the blanks before and after the decimal point, it will work.
Try:

Code:

        (A:AIRSPEED TRUE,knots) 20 &lt;
        if{
          1 (&gt;L:TAS,number)
        }

YES: XML coding is strange indeed.

Regards
Vitus

TooLowGear · 3 Jul 2009

Vitus

How are you testing the value? In Black box I am still getting a 0 value. Do I need to make a text readout that is in the panel? Is there a limitation on Black Box that I was unaware of?

Thanks for all the help!

Vitus · 3 Jul 2009

I don't use blackbox - I programmed a small debug gauge for these purposes. It consists of several GaugeString Elements that show the status of various variables.
I added the code posted above to an update object and added the line:

Code:

TAS:..................%((L:TAS,number))%!1.1!

to my debug gauge. And it showed 1.0.

Are you sure that the gauge/element that contains your code is embedded in your panel.cfg and updated?

TooLowGear · 3 Jul 2009

I tried putting the gauge in the 172 in place of the flaps gauge and i have the same results

Black Box code string looks similar

Code:

<String>%((L:TAS,number))%!13.2f!%(' L:TAS')%!-6s!</String>

It just reads the variables in the gauge. Maybe I am missing something more basic. But I will try to place the string in a real gauge right now.

Code:

<String>%((A:AIRSPEED TRUE , knots) (A:AMBIENT DENSITY , slugs) * 0.002378 / sqrt)%!3.0f!</String>

It works when I replaced the default KEAS string gauge with the new but I am still worried why I could not get black box to read.

I have a feeling the issue is currently the one typing this message.

Well now that issue is resolved, back to the EGT gauge which is still giving me a similar issue.

Thank you very much Vitus for your wonder patience and help.

TooLowGear · 3 Jul 2009

I lied

Code:

<string>%((A:AIRSPEED TRUE,knots) (A:AMBIENT DENSITY,slugs) 0.002378 / sqrt *)%!3.0f!</string>

is the correct equation, which makes the string useless and the gauge disappear

it is supposed to be TAS x sqrt((ambient density/0.002378))

TooLowGear · 3 Jul 2009

So for (A:Ambient Density,slugs) I am getting a reading of 0.03 which at 33,000 feet it is actually 0.0077 - in FS according to FS.

What variable would tell me the density of the air at the altitude of the aircraft?

Im going to take a break. Been working too long at this.

n4gix · 3 Jul 2009

Vitus said:
I didn't check your complex example but the last code snippet you posted. The result: the same. It didn't work. BUT if you delete the blanks before and after the decimal point, it will work.

YES: XML coding is strange indeed.

Regards
Vitus

Actually, XML syntax follows very precise, literal rules, and spaces are critical!

For example, in this example, the trailing comma delimits the end of the variable name:

(A:AIRSPEED TRUE , knots)

Consequently, it will fail because the space between the E and the , becomes part of the variable's name, which is not recognized by the parser!

In the example below, the extra spaces after the comma delimiter are ignored, so the expression will still be parsed and evaluated correctly.

(A:AIRSPEED TRUE, knots)

beatle · 3 Jul 2009

Well, to be technically acurate, XML doesn't care about whitespace at all. The sections you guys are talking about aren't technically XML, they are just payload data in an XML element (in this case, RPN script code). It's the RPN Script parser that both the panel and animation systems use that is picky about spaces (why whoever did the XML gauge system originally thought allowing spaces in the var names was a good idea, I have no idea; but then again, I also haven't figured out why they thought RPN was a good idea either :-> ).

n4gix · 3 Jul 2009

Okay, I should have been more explicit. The schema used for gauge XML script is fussy about white space(s).

In any event, xxx , is invalid; xxx, is valid.

BTW, you've conflated this thread with another, as this has nothing to do with payload stations... :stirthepo

TooLowGear · 25 Jul 2009

Wow Thanks a lot. That has been very informative. Thank you for all the help. I noticed whitespace is critical in xml....grr.