Unable to understand OTX configuration for landing gear

[Allan Bennett]

Posted by EarlyBird on 17/08/2020 09:03:11:

Allan,

A screen shot.

Cheers

Steve

Thanks for going to so much trouble, but I'm afraid I'm being a bit slow here. I've just tested your two lines in OTX Companion simulation, and it does as you say, but I don't understand why.

MAX is a constant having a value equal to 100, according to OTX University (although I though is was a constant of whatever value you give it). So the two lines seem to say to me that the value will be 100 with !SA^, and will also have a weight of 100 with SA^. Why doesn't that result in 100 for all three positions of SA?

I'm persuing this only out of curiosity, since I've got a couple of solutions which I do understand, so please feel free to duck out of this discussion if you think I'm being too thick!

[EarlyBird]

Because SA^ has a default value of -100%

The 100 in the mix line is the % of the default value to send to output.

Which works out to be 100% of -100% = -100%

If you changed the 100 to 10

then 10% of -100% or -10% would be sent to output.

Cheers

Steve

[Bob Cotsford]

It works because the first line has a switch set so it is only active when SA is not up (!SA^) so effectively the second line replaces it when SA is up. I think it would work just as well with the second line as MAX -100 SA^ as switch SA is providing a REPLACE function and might read more clearly if it works that way. Maybe I'll try it in Companion for S&G.

So here it is in Companion and it seems to work. Switch SA is now purely a control, weight is set by the MAX input.

Edited By Bob Cotsford on 17/08/2020 12:01:48

[EarlyBird]

Yes but Bob you have just confused me. I thought I understood.

What does it look like on the Taranis screen.

I have not got to companion yet, I have only had my Taranis for a couple of weeks.

Another thing is I do not like the idea of using -100, why I can not explain apart from in my mind -100 reverses the servo.

It's all interesting stuff.

Cheers

Steve

[Bob Cotsford]

In this case using MAX the weight is effectively a positional control, with switch SA in one position it is 100 and the other way -100. I guess you could look at it as 'reversing' in that MAX is positioning the resting point of the 'servo' at one end of it's travel arc and SA is reversing the servo extremity if you wanted but as the servo has no intermediate travel in this usage does reversing apply?

ps - it will look the same on your screen but it will have a blue background . I'll see if I can photo the editor lines once my phone is recharged.

[EarlyBird]

Ok Using your method I now have

CH5 100 Max 'no switch assigned

+= 100 switchSA SA^ ' switch A up added to the mix which does not work

Hmm what happens is the first line gives a value of 100 the second line a value of -100 these are added together and give 0.

How to fix?

For SA use Multiplex and change from Add to Replace.

It works as required.

I understand more now than I did when I got up this morning.

Another good day in North Lincolnshire, despite the weather stopping me flying

Cheers

Steve

[Bob Cotsford]

Yep, it's easy to forget that the additional mix lines default to 'ADD', replace and multiply functions can be useful tools too.

Time for lunch already? I think I have some peppered beef lurking in the fridge. Not for long!

[Allan Bennett]

Steve and Bob, thank you again. I was thinking that -100 would have done the trick, and that's turned out to be the case, as well as Steve's original lines. So now we've got several one-line ways of doing it

I only 'discovered' the ADD/REPLACE/MULTIPLY options, and their effect, the other day -- very useful.

[Mike Blandford]

Another "one mix line" method that may help, or be of interest.

A channel with no mix line defaults to 0% (centre position), but this may be changed by using the sub-trim in the outputs settings that moves the centre position.

So set the sub-trim to -100% and then use a mix line of:

+100% MAX switch(!SA^)

With SA up, the mix line is ignored so the output is the -100% set by the sub-trim.

With SA not up the mix line outputs +100%.

Mike

[Allan Bennett]

Sounds like we've got a competition going here for the best one-liners

Thanks Mike, but I'm sure if I used that structure some time in the future I'd have forgotten about the Output line and be wondering why the Mix is the the way it is.

[Mike Blandford]

I posted that more to explain how some things work. I've seen people asking how to set up 3-position flaps on a 3-pos switch. My preferred way is to use a mix with a switch as the source, then set the three output positions in the output screen by adjusting the 2 endpoints and the sub-trim for the middle position.

Mike

[MattyB]

Posted by Allan Bennett on 15/08/2020 20:46:26:

...I like the idea of Matty's 'unknockable' switches too, though the need for a sequence of movements to lower the u/c on my landing approach is not very attractive -- I've got enough to do at that point in the flight! I'll have a look at it though, for I'm sure the 'unknockable' aspect could be applied only to u/c up, leaving u/c lowering as a single flip of the switch.

Belated update....

I liked the above dea so much I have updated my unknockable switches to offer this option - you can download the OTX file for OpenTX v2.3 with documentation and all the sound files needed on RCSettings. The good news is I was able to simplify the logical switches to 3 per implementation which makes it much easier to setup. Let me know how it goes!