Sbus Servotravel not equal

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augur
Posts: 51
Joined: Thu 01. Nov 2018 11:26:02

Hi.

I am facing the behaviour that the servotravel is not equal. As Sbus is a digital protocol I am thinking about the reason why this happens. The output in servomonitor of my T14SG is at 100% in both directions. Sprit does detect 97% and 100%.

In my opinion it should be equal or does I miss something?

Cheers
Nils

PS. I know it perhaps could not be felt during flight but it is interesting.
ZeXx86
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Posts: 12836
Joined: Mon 29. Apr 2013 16:06:44
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Hi,

this is because your center pulse is not exactly in the middle.
I guess that you are talking about Pitch channel. Center of the pitch channel is determined from center of aileron, elevator, rudder channels.
So you have to make sure that you are not using any subtrims and trims in your radio for these channels.

In other words it is enough to make sure that 0% in your radio is 0% in the Spirit Settings/Diagnostic tab. If not, then this is the problem.
With default radio settings it should match exactly.
Spirit System developer
augur
Posts: 51
Joined: Thu 01. Nov 2018 11:26:02

Hi.

That’s the interesting part. In the Servomonitor (direct Servo output in T14sg) I see -100% , 0% , 100%. In Diagnostic tab I see -96%, 0%, 100%.

It seems to be correct centered for me. I have to check if it is pitch only (I am on business trip) but as I remember it is the case for most of the channels including aileron and elevator.

Cheers
Nils
augur
Posts: 51
Joined: Thu 01. Nov 2018 11:26:02

Hi.

It is the case for all channels.

Cheers
Nils
ZeXx86
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Hello,

if you will have a trims or subtrims for a channel then this is detected during initialization as a new center.
But then end points will not match. So this is only matter of radio configuration. There is nothing else you could do about it.
With our Futaba radios it is for example perfectly +/- 100% just with a default configuration of radio and Spirit unit (through S-BUS protocol).
Spirit System developer
augur
Posts: 51
Joined: Thu 01. Nov 2018 11:26:02

Mhh. That’s not the case for mine. In Servomonitor (which shows trim setting) it is perfectly -100/0/+100. Do you use Sbus2 with telemetry? Perhaps there is a difference between standard Sbus and Sbus2.
ZeXx86
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We and thousands of other pilots are using SBUS/SBUS2 for many years.
But if you are using SBUS2 port you should also use the FrSky integration cable (with modification).
For SBUS(1) wiring is according the manual - Futaba S-BUS.

In any way this has no effect on the channel end points. The only thing that has effect is channel configuration in your radio.
Do you have standard, unmodified channel layout in both Spirit and your radio? This could have an influence.
Spirit System developer
augur
Posts: 51
Joined: Thu 01. Nov 2018 11:26:02

Yes, totally unmodified. I will ask in another forum, perhaps it is a personal issue combined with the products used...
ZeXx86
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Posts: 12836
Joined: Mon 29. Apr 2013 16:06:44
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Well, you can fix the issue easily in the TRAVEL ADJUST menu. Travel can be enlarged to one side to reach 100%.
Then all will be fine.
Spirit System developer
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