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Stream Deck + and XPlane. rotary knobs for HDG, SPEED etc. Great, but too much latency. [update: SOLVED]


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Got this brand new puppy (Elgato Stream Deck +) based on the notion that I could use the rotating knobs for HDG, SPEED, ALT SEL and BARO, as well as range. Just like in the real airplane, the knobs rotate with a ratcheting feel. It's no problem at all mapping the rotaries to the appropriate keypresses. First assign key sequences to the relevant CL650 FCP 'commands', then assign the same key sequences to the clockwise and counterclockwise actions for a knob in the StreamDeck software. With the mapping I did, every notch of clockwise or counterclockwise rotation of a knob corresponds to a 'HDG knob up' or 'HDG knob down' keypress. I did same for ASEL, SPEED and other knobs. 

There is an issue, and it's either on the Xplane side of things or with the Stream Deck software. When I turn the knob at a "normal" rate, i.e. same as I would turn it in the real aircraft, there is a noticeable lag in movement of the heading bug. It appears to me that the keypresses are sent repeatedly at a fixed rate, which is too slow. As a consequence, the heading bug keeps moving even when I stop rotating the knob, until all the "rotary knob" keypresses have been absorbed by XPlane. A further side effect is that reaction to any presses of the actual keyboard is delayed, again until all the "rotary knob" keypresses have been absorbed by XPlane.

I looked around the StreamDeck SDK documentation, and these made me think that the StreamDeck software, out-of-the-box, sends not only a key-down but also a key-up command for every notch of wheel rotation, which further increases XPlane's workload.

The solution most likely lies in writing a plugin for the StreamDeck software or or for XPlane - both of which are possible, but beyond my abilities - . But just on a hunch, I am posting this here as well, perhaps the HotStart folks have an idea on how else this could be done? (Note: as of this writing, the folks at Elgato have not yet updated the SDK API for the rotary knobs, so a solution might be forthcoming from their side.) 

As is, what I have done is still usable, but you mustn't be in too much of a rush when turning the knobs.

The StreamDeck+ seems almost born for fsim use. The knobs are also have a momentary push function, just like the FCP knobs. So if you push the HDG knob, I have mapped it to sync the heading bug to the current heading - exactly like the real knob. And it gets even better: You can map 2 different actions to a knob push. In the picture, you can see that my leftmost knob is mapped to change the DCP1 range. But if I give it one push, then the mapping changes to PITCH/VS wheel up/down.

Another neat thing is that the StreamDeck + has a touchscreen just above the rotaries, and can detect left and right swipes, allowing me to swipe to a second page of mappings. On my second page, I have a rotary set up for setting the BARO QNH/altimeter setting, with a knob push mapped to toggle between STD and preselected QNH. It's just great!! And on my third page I have the 10th stage bleed buttons mapped,  so it is totally easy to transition from APU to engine bleed source and back. I'll also setup anti-ice controls when I have a chance, and then figure out how to post the mapping profile here - that is also possible. I don't know how many pages of mappings you can have, but I'm at 4 pages so far and it is still offering me the option of adding more.

Final detail: you can download the StreamDeck software even if you don't have the hardware, which allows you to see how easy it is to configure. I am totally impressed with what Elgato have come up with here. And full disclosure, I have no connection to them whatsoever.




Stream Deck + CL650.png

Edited by Lightcivvie
Title edit to reflect new info
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I'm not using StreamDeck+, but Loupedeck Live which is a very similar kit (6 rotating knobs + 12 touch buttons and some more).
I originally also used 
keyboard mappings, but found it quite cumbersome to set all those up in X-plane, and was also not entirely happy with the speed of the rotary knobs (too slow for some commands and too fast for some others).

Then learned about XMidiCtrl, which is essentially a MIDI Controller interface into X-Plane.

It takes a bit of setting up (mainly on Loupedeck side, StreamDeck may be easier here) as well but I find it more flexible its use and it has solved the speed/lag issues with the knobs for me. It comes with an example file for the CL650 out of the box, but I have created a more expanded one that covers all FCP/DCP/CCP + baro controls.
It works really well (also in XP12) - happy to share if helpful.



Edited by marcvc
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16 hours ago, Pils said:

XMidiCtrl is great, I use it with my X-Touch, but how would one get a StreamDeck to present as a MIDI device?

Don't have experience with StreamDeck, but it will require a MIDI plug-in (just like with Loupedeck) through which you then need to setup your MIDI commands to go to XmidiCtrl; a quick google search gives e.g. https://trevligaspel.se/streamdeck/midi/index.html

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  • 1 year later...
On 12/16/2022 at 4:44 PM, Pils said:

XMidiCtrl is great, I use it with my X-Touch, but how would one get a StreamDeck to present as a MIDI device?

Download the MIDI plugin from the Elgato online shop - the one from Trevliga Spel - and install it. Can be accessed directly from inside the Elgato Stream Deck app. 

This will add some draggable action items to the sidebar. You then drag a Control-Change to a dial (or button), configure to send the appropriate MIDI change command on the appropriate channel, and presto!

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  • Lightcivvie changed the title to Stream Deck + and XPlane. rotary knobs for HDG, SPEED etc. Great, but too much latency. [update: SOLVED]

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