Center value C9X

[mizuta1951]

The center value on the limits tab is originaly 1500uS.
But the FUTABA system uses 1520uS for center.
My exsiting planes are all using this center value (1520uS).
When I try to switch the TX to TARANIS, I need to reset all the center value from 1500uS to 1520uS.
Is there any way to change the default center value on C9X ?

[Romolo]

Well the center in c9x reflect the center in opentx
the main problem is that if you need a non standard center (1520 is a standard for futaba but is not for jr/multiplex) you will waste a lot of memory even for unused channels as c9x will change on all 32 taranis channels.
Changing radio means to recheck centers and excursions, you cannot skip this rule !!
It's not only a center problem indeed, the excursions on taranis/open9x are more extended than on a futaba, what we should do, reduce them to "futabize" the software ??
No thanks....

[jhsa]

there's another problem Romolo.. It's a bit more complicated than that
The futaba servos don't center on 1500 and that will reduce the travel on one side.. if you own a futaba servo you could open it and verify that the stopper thingy won't be in the middle at 1500

João

[Romolo]

João,
opentx has PPM_CENTER so that's not the problem...

BTW JR servo center at 1500 as well most china servos...

[jhsa]

I was just mentioning that some servos might have weird centers of course we have the PPM center feature and it is great.. that allows us to even mix different brands and have the servos centering properly as lçong as we know what the center pulse is..
But I also agree that if you use the futaba weird stuff in all your models, it can be a bit overwhelming changing all the channels on all models to the correct pulse width
maybe an option to set the default pulse for the radio? even more flexible? just an idea..
For me it makes no difference I gotta say, but for some others it might

João

[Flaps 30]

there's another problem Romolo.. It's a bit more complicated than that
The futaba servos don't center on 1500 and that will reduce the travel on one side.. if you own a futaba servo you could open it and verify that the stopper thingy won't be in the middle at 1500

The percentage difference between the standard (JR/rest of the world) and Futaba (in a world of its own) in this case happens to be two percent of the total throw. IMO I reckon that you will find in most systems that the mechanical 'slop' and servo hysteresis/dead band will almost if not equal that and more.. So the problem isn't as big as some will make out..

Two ways to fix this. - For those that see this as being a big issue. Give up on the Taranis and put it on Ebay and carry on with your Futaba stuff. The other way is to make a small (2%) offset on each channel. Better still if you really insist, adjust the mechanical linkages to recentre the controls/surfaces.

Having said all of that. I thought that the World of proportional control set the standard many decades (like four) back regarding the centre as being 1.5mS. This is for analogue servos of course. Digital servos is another can of worms that is a bit more complex.

[jhsa]

well, as I stated before, it doesn't affect me even if I'm a lazy bugger sometimes.. errr, ok, most of the times
But I was just trying to understand other point of view.. And as everybody says that this system is supposed to be veeeeery flexible, I've just thrown an idea in the pot.. Now is up to the developers to implement it or not. I won't nag about this one, that is for sure.. I will about other subject though

João

[Romolo]

Flaps, there is no need to use offset, use PPM center.
It's far better, it has been implemented also considering multiples servos (center at 1610)

[ShowMaster]

I've always wondered why the output arms and wheels aren't offered by some company that allow them to be mechanically centered?
Maybe a 2 piece setup. One with the splined FM that goes on the servo shaft the other is an arm or wheel that you reposition for 90 deg and lock on place with screws? Usually the servo end stops allow for more travel than is normally used so a 2% additional travel as you say flaps30 shouldn't matter.
Rocket city made an adjustable servo arm that allowed you to dial in the exact travel and hole spacing from the center servo screw. I used it regularly on my nitro throttle servo to get full travel and no excessive travel to stall the servo.
The older servos could have the centering adjusted through the servo screw hole with a jewelers screwdriver. As servos got tighter I guess that wasn't practical?

[gohsthb]

What is the difference between offset and ppm center? Don't they both do the same thing?
-Gohst

[jhsa]

I think the PPM center will move the limits acordingly??

[Romolo]

The difference is huge...

ppm_center moves the center but leaves the +/- travels the same by moving also the limits...
offset move the center but leave the limits where they are, so +/- travels get different.

[MikeB]

On er9x/ersky9x, you can use the sub-trim to move the centre by 2%, and if you also enable "autoLimits" at 2%, the endpoints will be moved by the same amount as the sub-trim. Sounds much the same as ppm_centre!

Mike.

[mizuta1951]

Thanks for discussing my issue.
Honestly it dose not take so much time to re-enter the center value on the limits tab, it just helps me to be little more lazy.
I just wondered that if C9X had an one small entry field or drop down tag which can change the default center value, it will really help me and others who are used on Futaba system.
I really love the flexibility of OpenTX, and also I will be glad to be more lazy on setting up my model.
Thanks again !