UDP DRefs - Does not seem to output any valid data

Question

Hi all,

 

I am trying to use UDP to input/output data with X-Plane 11 Demo(looking to buy full, but trying out what I can do first).

I am using Ubuntu 17.04 64 bit. But was trying it in Windows with the same result.

 

I am able to pass data to simulator using some hardware components like joystick/buttons connected to Arduino and that works fine. When I am trying to receive data from X-Plane 11 all of them are null. E.g.

Bytes:

[68, 82, 69, 70, 43, 0, 0, 0, 0, 115, 105, 109, 47, 99, 111, 99, 107, 112, 105, 116, 50, 47, 99, 111, 110, 116, 114, 111, 108, 115, 47, 112, 97, 114, 107, 105, 110, 103, 95, 98, 114, 97, 107, 101, 95, 114, 97, 116, 105, 111, 91, 48, 93, 0, <0s to fill to 509 bytes>, 0]

String:

DREF+ sim/cockpit2/controls/parking_brake_ratio[0]

Formatted:

DREF0    | REF: sim/cockpit2/controls/parking_brake_ratio[0]    | VAL: 0.0

 

4 bytes that should be responsible for value are always 0, 0, 0, 0. I have to use UDP as it is part of my project.

However, if I try it with X-Plane 10 I am able to receive data without any issues.

Does anybody have the same problem?

 

Kind regards,

Igor

Answer 1

I have an example Android project that you can look at which implements receiving of UDP DataRef packets from X-Plane 11: https://github.com/waynepiekarski/XPlaneMonitor

You need to enable the sending of these packets in the X-Plane settings, and they arrive in a format like this:

["DREF+"=5bytes] [float=4bytes] ["label/name/var[0]\0"=remaining_bytes]

I noticed in earlier versions of X-Plane 11, you would get 0.0 valued floats when you enabled a dataref, and you had to exit and restart X-Plane to get actual updates. This was fixed recently, but would have been a problem when you wrote this question. You might want to try it again.

Just recently I found a great blog post which explains in great detail how to receive datarefs and also how to send them back to X-Plane, which is worth reading through: http://blog.shahada.abubakar.net/post/linux-udp-network-client-library-for-x-plane-10-and-11