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[Noob] Export (readonly) LVars to the outside without gauge?

F

_f4l0_

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2
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germany
Hello FSDeveloper,

I need to read some LVars from an external program. I read the 'C Gauges Tutorial', at least one version worked and I saw the gauge in P3D/FSX. However, I like to build a plane independent approach. Something like fsuipc, a module which is loaded at startup. I wonder if there is already such a solution since I read a lot of threads where people asked the same question. Sadly, I was not able to find there a satisfying answer/full example.
I guess a simple example which just reads one LVAR (execute_calculator_code) would be sufficient. Implementing communication to the outside via IPC or TCP should be easy.

The reason: I'm very new to the FSX/P3D SDK usage. Previously I could extract most of the data I need with SimConnect but it seems that some 3rd-party plane developer (eg Majestic Dash8) doesn't eg. provide RPM data via SimConnect.

I hope this question was not answered already.
I appreciate any tip or pointer to the solution!

Thanks
Olaf
 
Check the Cabin Comfort example in FSX/P3D SDK. Could be useful as a starting point.

Tom
 
I have such a module mostly written. I got bogged down getting a named pipe to provide all the functionality that I was looking for.
I can trim it down to be a module that will load into FSX and retrieve LVars. You can add whichever type of interface you want to retrieve the information from outside FSX.
I'll try to post the source code here in a day or two.

Doug
 
Here is a basic dll file with functions to work with LVars.
You will need a dll.xml entry like this to load it:
Code: 
<Launch.Addon>
<Name>lvar interface</Name>
<Disabled>False</Disabled>
<ManualLoad>FALSE</ManualLoad>
<Path>.\modules\lvar_interface.dll</Path>
</Launch.Addon>

Doug
 

Attachments

Hi @ddawson, i've test your dll file and works very well.

I have a question:

There's in gauges.h a way to create or "subcribe" to an event like "6hz" event in simconnect?

I try to avoid de use of multi threading.

Thanks.
 
The Cabin Comfort example Tom referred to does define "Update" methods in a couple of the classes it uses. These should get called at 18Hz. that would, in my opinion, be an overly complex way to get such a result.
Why not use a Windows timer? Straightforward and simple.
You could also use SimConnect, as you suggested. You can use it within a gauge or module.
 
Thanks @ddawson for your reply.
I chose to use SimConnect. I agree with you, the Update methods in the Cabin Comfort example are too complex and I don't need a gauge type interface. So, with SimConnect, I have the possibility to send messages to the FS and maybe some menu to control some options (debug, reset, etc).
I use the 6hz event of SimConnect instead a Windows timer because (i think, i'm not sure yet) this event is more frame-friendly.

Thanks again, regards.
 
Data transfer rates via SimConnect are extremely fast.

Using 6hz as a data update rate is horribly inaccurate.
 
WarpD said:
Using 6hz as a data update rate is horribly inaccurate.
Click to expand...
@WarpD thanks for your comment.
6hz maybe is inaccurate but i have no problem with that. I use it to send data via serial port to a microchip pic based display. Is working realy fine. On the other hand, I try to do this task using multi-threading, launching a thread in the module_init method of the dll and I can't use the execute_calculator_code function (I only use that to retrive the PCSTRINGZ with the name of the VOR/ILS tuned).
Using the 6hz method, i only use a thread to listen the serial port and send the commands to the FS.
 
Ok... there are far better and more accurate means that have zero frame rate issues... but... (shrug)
 
Hello DDawson. Thank you for files. Do you know why the below code works for FSX but not FS9? Is it possible that FSUIPC v3.999z9 can't do ipc.readLvar? Is there a function way to readLvar, and if so, what is the syntax?

Code: 
while 1 do

  FDValue = ipc.readLvar("L:CpitCmdrSetValue")
  ipc.writeDBL(0x66D0,FDValue)
  ipc.sleep(50)

end

With FSX, I found out that FSUIPC v4.84 could not run the code below but 4.975 could because v4.84 did not have the feature of event.Lvar so FSUIPC v3.999z9 certainly did not:

Code: 
function writeFDCmdr(varname, value)
    ipc.writeUW(0x66D0, value)
    end

event.Lvar("L:CpitCmdrSetValue",100,"writeFDCmdr")

oops! Well, don't I feel a bit silly. I had forgotten that I had assigned the throttle axis to 66D0. I did this so I could use the throttle axis to control up to 4 engine throttles, either together or separately as well as prop pitch, mixture, cowl flaps, flaps and spoiler. Re-assigned 0x66E0 and life is good again.
 
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