Transponder Modes and IDENT command readable by 3rd parties

For MFS to further support hardcore simmers flying on online flight networks (eg. PilotEdge), we need MFS to make the Transponder Modes (ie. OFF/ON/STBY/ALT) and the Transponder ‘IDENT’ command readable by third-party network clients (running in the background).

Currently, simmers need to switch between MFS and external client windows during (critical phases of) flight to change the transponder mode and/or to IDENT to ATC. This greatly interrupts the immersion and effectiveness of doing advanced simming in MFS. Moreover, in MFS VR, this current limitation is worse, since switching to external windows requires snapping in and out of VR …

We LOVE the latest implementation of the ‘dual comms monitor’ feature in SU2 as wished by the community. The above-described wish would make MFS fully compatible (and thus truly practical to use) with online flight training networks, such as PilotEdge.

Please allow third-party apps to read our Transponder Modes and IDENT commands in SU3. Thank you for all the great and hard work so far!

Agreed. Voted

This would be huge!

Agreed and voted.

I guess that this would be a simple thing to add to the sim?

Yup! That, and monitoring COM2. It’s not a sim until it has the basics working…and this is basic.


Def needed , hopefully it’s an easy fix.

Note that the transponder mode is available via the TRANSPONDER STATE simvar. I have not yet found a way to detect when the user presses the ident button through SimConnect. Once I have that figured out, I will add support to vPilot and the PE client.


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Hi Ross, to confirm - am I correct in thinking Transponder State still isn’t supported by vPilot? new to Vatsim this week and noticed the TBM transponder controls weren’t sticking me in mode C, I’ve seen all the historical posts about the lack of FS > vpilot communication on this front, is this still work in progress?


That’s correct, the TRANSPONDER STATE simvar is not yet read by vPilot. I’m waiting to hear back from Asobo about how to detect (through SimConnect) when the user presses the ident button. At that point, I will add support for both the transponder state and the ident button.

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Is this still not solved?

Asobo has added an ident simvar. However, only the WorkingTitle G1000 NXi mod actually has an ident function that sends this information to ATC.

Asobo still needs to implement the functionality into the existing instrument panels.

So the ident button on the G1000 NXi mod works on VATSIM?

Don’t know … it depends on if the mod developers implement the simconnect variable.

Yes, the Working Title mod has worked for quite a while. Asobo implemented functionality in the almost all of the default avionics in SU5 or 6. Of the top of my head, I believe only the G3X avionics (like in the Carbon Cub) still lacks the ident functionality.


Are you reading the TRANSPONDER IDENT simvar for this? I’d like to implement this in the A32NX. How do you interpret the various states of the TRANSPONDER STATE simvar?

-e- implementation:

The logic is:
TransponderOn = mode switch = ON, or AUTO and airborne.
0 if transponder is not powered
1 if transponder mode switch is STBY
3 if TransponderOn and ALT reporting off
4 if TransponderOn and ALT reporting on
5 if mode switch = AUTO and on ground (mode S)

A:TRANSPONDER IDENT is set true (via K event) when the transponder is ON or AUTO and the ident button is pressed (MSFS resets it after 18 seconds).

Does this line up with your implementation?


Yes, that lines up with how I use the vars. On VATSIM, we only simulate two transponder modes: standby and mode C. So I send standby if the “TRANSPONDER STATE:1” simvar is less than 3, otherwise I send mode C.

And if I see a value greater than zero in the “TRANSPONDER IDENT:1” simvar, I trigger an ident. I use my own timer to keep identing for 12 seconds. I only read the value when it changes, so it’s not like another 12 second ident will be triggered if the value is still 1 after my timer expires.

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Brilliant. A32NX should be working perfectly in a few days once the QA testing is done.

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