Limited Servo Movement?

mapes12 · Post by **mapes12** » Sat Mar 11, 2017 4:09 pm

I'm setting up a new model. Tx is a Taranis X9D running ERSKY9X. Hobbyking digital servos. My problem is that when I move the sticks I see the servos move but stop before I've applied full travel to the stick. They stop moving and there is about 15% of stick travel left

Sorry if this has been asked before. I've searched on the forum but can't find an answer.

Daedalus66 · Post by **Daedalus66** » Sat Mar 11, 2017 4:39 pm

We need more info.

Is the transmitter working normally with other receivers and servos? Have you calibrated the sticks? What does the Monitor screen show? Are the bars moving normally the full amount? In other words, is the problem in the transmitter?

Next the servos. Which HK servos are we talking about? Are they programmable?

mapes12 · Post by **mapes12** » Sat Mar 11, 2017 5:13 pm

Stick calibration is OK. Your suggestion to check the movement on another model has demonstrated the same result i.e. no servo movement with about 15% of stick servo movement left. I hadn't noticed it before. Which got me thinking. A while ago I had an issue with a 3 POS switch and the advice I got from you guys was to drop the Weight in the Mixer to 80 so that the flight controller was receiving the correct ms range for its specification. So I just did the same on a servo channel and dropped the Weight to 80. Now I get full servo movement throughout the full travel of the stick. I'll get the ms limits from the Limits screen later but do you think I'm on the right track in solving this?

I'll also post the servo specs later but they are not progamable.

Post by **jhsa** » Sat Mar 11, 2017 5:22 pm

Does your model have a flight controller between the receiver and the servos?

João

Daedalus66 · Post by **Daedalus66** » Sat Mar 11, 2017 5:41 pm

Sounds like you do have a flight controller and it needs Spektrum pulse widths (1100 to 1900us for +/-100%). So reducing limits to 80% (or more precisely 78%) is the right thing to do.

What's apparently happening is that the FC only accepts 1100 to 1900, while the 9XR Pro at 100% is putting out 1000 to 2000. So going to 80% is needed to match the Tx to the FC.

By the way, you should use Limits for this purpose, rather than adjusting the mix weights.

mapes12 · Post by **mapes12** » Sat Mar 11, 2017 6:50 pm

jhsa wrote: ↑Sat Mar 11, 2017 5:22 pm Does your model have a flight controller between the receiver and the servos?

Yes it does. An Eagletree Guardian.

Daedalus66 wrote: ↑Sat Mar 11, 2017 5:41 pm Sounds like you do have a flight controller and it needs Spektrum pulse widths (1100 to 1900us for +/-100%). So reducing limits to 80% (or more precisely 78%) is the right thing to do.

What's apparently happening is that the FC only accepts 1100 to 1900, while the 9XR Pro at 100% is putting out 1000 to 2000. So going to 80% is needed to match the Tx to the FC.

By the way, you should use Limits for this purpose, rather than adjusting the mix weights.

Ok. Do I drop the Limits to 78 on both sides then? Why should this be done in the Limits screen and not the Mixer screen? I'm Just trying to understand the difference.

Your spot on with the 1100 to 1900us spec. That's what's in the Guardian Manual.

mapes12 · Post by **mapes12** » Sat Mar 11, 2017 7:53 pm

I've answered my own question with regard to changing the Limits. It's both sides and I now get replication of Spectrum outputs of 1100 to 1900 as the Flight Controller is specified for. However, if I leave the Limits at 100 but change the Weight in the Mixer Screen to 78 then the 1100 to 1900 is exactly the same. So I guess my question in this conundrum is why use the Limits screen to make the adjustment and not the Mixer screen?

So, rule of thumb for me in using this Flight Controller is to back off all channels to 78 (subject to clarification as to Limits or Mixer screen) for the control surfaces. For an electric model should I leave the settings as they are or back that off to 78 as well? I'm clear on IC as it's a servo input.

Post by **jhsa** » Sat Mar 11, 2017 8:47 pm

I think you should take the good advice about using the limits in this case.

The limits are actually hard limiting the output, That means, nothing that you can do in the mixer will make the output go over the values you set..
If you use the mixer, and add more than one mix in the same channel, you might go over the acceptable value if you leave the limits at 100%

I will give you an example, even without adding extra mixes, just using the trims..
Do what you say, reduce the mixes and leave limits at 100% as you say.. Now go to the limits menu and look at the pulses value while you move the sticks to both sides. You will have, as you know, something like 1100 to 1900.
Now move the trim for that stick, you will see that the side you move the trim to will go over the maximum value you want to allow. In other words, if you need to trim the model, you will have the same dead band problem.

Of course, you do what you think it is right for you, but people here gave you the right answer for your problem. You agree with it or not

Up to you..

João

Daedalus66 · Post by **Daedalus66** » Sat Mar 11, 2017 9:18 pm

There's your answer to why use Limits. Yes, Weight will do the same thing -- until you introduce other issues. There's a good reason why Limits are called Limits. They do what the name suggests.

mapes12 · Post by **mapes12** » Sat Mar 11, 2017 9:19 pm

Thank you. And I will go with your good advice. Just a final question about electric models where the connection does not go via the FC. But I guess that's the same for all ER9X users, but do we also drop the limits to 78 to replicate Spectrum outputs?

Post by **jhsa** » Sat Mar 11, 2017 9:36 pm

What I do with models without FC, or with 99% of my models

Is use the limits to adjust the maximum possible servo throw without damaging them, or the control surfaces. Hard limiting before it breaks

Then use the mixer, the dual rate menu, or both, to adjust to the desired travel. But this is a completely different situation, as the servos are normally the only limitation I have. No flight controller demanding a specific pulse width range..

João

mapes12 · Post by **mapes12** » Sat Mar 11, 2017 9:41 pm

Thank you Joao. What about electric models. Are ESC's expecting the same Spectrum pulse range? None of my FC enabled models have the THR going via the FC. They are a direct connection to the Rx.

Post by **jhsa** » Sat Mar 11, 2017 9:50 pm

Normally you calibrate the ESC's to your radio. it will then learn it's pulse width range and adjust accordingly. Please read the manual of the ESCs. It should explain how to calibrate.

João

mapes12 · Post by **mapes12** » Sat Mar 11, 2017 9:54 pm

Ok Chaps. I think I've got all the info I need now to set up these FC enabled models. I would just like to close this thread by saying a very BIG thank you for helping me out.

Mark

Post by **jhsa** » Sat Mar 11, 2017 10:17 pm

No problem. Glad to help.. Good luck with your setup.. Don't hesitate to ask if you need information..

João

Daedalus66 · Post by **Daedalus66** » Sun Mar 12, 2017 1:31 am

I have two basic approaches.

If the model uses Spektrum standards -- that is its electronics are DSM and control setups are built around 100% = 1100-1900uS -- I have a standard template which emulates a DX4e and I use that as a starting point for programming. It has TAER channel order, channel 5 is -100/0/100, and channel 6 is on the TRN switch giving 100% when pulled. All Limits are set to 80% except low throttle, which is left at -100 (in accordance with Spektrum instructions to set throttle trim to full low). Aileron and Rudder (channels 2 and 4) are reversed (INV in Limits Menu) to match Spektrum directions. Also, D/R is set up to 100/85/70% with 25% expo. From that template I develop the model, maybe with extra channels, etc.

On the other hand, if I'm using an FrSky receiver, I generally start from scratch (or from an existing model that is something like what I need) and build the model around 100% = 988 to 2012uS, the ERSky9x standard. I usually use TAER, but there's no particular reason to do so.

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