RTH switch setup for Futab 9C Instuctions:

[martinv]

Updated 3-8-11

Return to Home (RTH) Activation Switch Setup
First a diagram of the basic concept:



-------------

Instructions for the Futaba 9C
The following instructions will setup switch A to turn ON the autopilot when in the up position.
To get the 110% level required to reliably turn on RTH, 2 Program Mixes must be setup on the switch you use to activate RTH. These 2 mixes will combine to ignore the throttle stick and output a 110% throttle level.
For the following to work you need to make sure your throttle stick control does NOT exceed 100% when fully engaged. Check your END POINT menu and verify the throttle setting max is not over 100%.

1. Press Model/Page
2. Press Model/Page again
3. Select PROG MIX 1
4. Set rate to -100% (or + 100% depending if your throttle is not reversed)
5. Press the Down arrow.
Confirm and set the following:
MIX: OFF (or on if switch A is on)
MAS: OFST
SLV: THRO
LINK: OFF
SW: A (or the switch you want to use to control RTH)
POSI: Up (or down if you want the down position to activate RTH)

6. Repeat step 3-5 using Program Mix 2 instead of Mix 1. Set mix 2 exactly the same as mix 1.

Now when you flip switch A it should turn on the autopilot.
--------------------------------------------------------------------------------------------
Setting up RVOSD to activate Return To Home (RTH) when your RC link is lost and when you flip your RTH switch.
1. Turn on your RC TX.
2. Remove your prop(s) and power up your plane.
3. With the RVOSD remote go to the menu item: "Set PCM FS point"
4. With the RTH switch OFF, Turn on full throttle.
5. With the remote, press right arrow to temporarily capture this value. Write it down. This is your 100% value
6. Turn on the RTH switch and capture its value. Write it down. This is your 110% value.
7. Temporarily disable one of the RTH switch mixes.
8. With the RTH swich on, adjust the throttle and keep capturing the value and adjust until the "Set PCM FS point" value is between the 100% and 110% value. Note the RVOSD will be going in and out of RTH during this and your motors will be changing speed a lot. Ignore the motors and trust the numbers.
9. Reenable your RTH switch Mix so both mixes are ON.
10. Verify everything works correctly. RTH should activate
--------------------------------------------------------------------

Recently I had an issue where I only had 1 mix set. It was not enough to activate RTH reliably. It would randomly turn on full throttle, RTH or quickly jump between the 2 which can be disturbing when you don't know the cause.
3-7-11: I discovered 2 mixes are required to completely bypass the throttle stick control. If you only setup 1 mix, the throttle stick will still have some effect on the throttle channel output. Previously I assumed the 2 mixes were increasing the throttle pulse length. On measuring it with an oscilloscope I found this was not the case, however 2 mixes are needed for the reason described in the first sentance.

[peecee]

This is how I set it up. I wrote it down incase I forget and though i'd post it here as it's a fairly common tx.

-------------
Return to Home (RTH) Activation Switch Setup
This will setup switch A to turn ON autopilot when in the up position
To get the 110% level required to reliably turn on RTH, 2 Program Mixes must be setup on the switch you use to activate RTH.

1. Press Model/Page
2. Press Model/Page again
3. Press ^Up arrow
4. Set rate to -100% (or + 100% depending if your throttle is not reversed)
5. Press the Down arrow.
Confirm and set the following:
MIX: OFF (or on if switch A is on)
MAS: OFST
SLV: THRO
LINK: OFF
SW: A (or the switch you want to use to control RTH)
POSI: Up (or down if you want the down position to activate RTH)

6. Repeat step 3-5 using Program Mix 2 instead of Mix 1. Set mix 2 exactly the same as mix 1.
------------------------------------------

Recently I had an issue where I only had 1 mix set. It was not enough to activate RTH reliably. It would randomly turn on full throttle, RTH or quickly jump between the 2 which can be disturbing when you don't know the cause.

Would this work

set 110 % on throttle (2.08 ms ) run wizzard , leave throttle at 110 % ,

to activate rth give full throttle, deactivate, decrease throttle.

it would require disciplined throttle managment ,but your thumb is always on the switch/throttle

or for those that want a switch .

set throttle up with dual rates

rate 1 100%
rate 2 110%

to activate
activate dual rate switch move throttle to full.
to deactivate
decrease throttle and flick dual rate switch .

I think I would wise to ad the dual rate switch to your take off/ landing check list

( dual rate off for take off / landing)

Brett

Ps for those with a 3 way switch , normal AP mode is set to say FBW for cruise and use the throttle to activate RTH instead of going to menu and changing AP modes

[martinv]

Another note,

The procedure I described above is for an independant control of RTH and is not the same switch as your autopilot modes (FBW, Level Flight, Heading hold..etc..). It is in addition to the 3 position switch. So you have RTH always availabe AND whatever mode you have selected in the autopilot menu.

It took me a while to realize this mode was even available.

Pre RVOSD3, I though the only way to activate RTH was to turn the TX off. I was very happy when I found out you could activate it with a seperate switch.

[peecee]

Another note,

The procedure I described above is for an independant control of RTH and is not the same switch as your autopilot modes (FBW, Level Flight, Heading hold..etc..). It is in addition to the 3 position switch. So you have RTH always availabe AND whatever mode you have selected in the autopilot menu.

It took me a while to realize this mode was even available.

Pre RVOSD3, I though the only way to activate RTH was to turn the TX off. I was very happy when I found out you could activate it with a seperate switch.

Hi Martinv

I setup dual rates on throttle Hi rate to 2.08, low to 1.9 something and set Rvosd failsafe to 2.04. I set up dual rates on a switch directly above the thottle so its easy to find. Works like a charm I did a ground test and turned the TX off and it activated RTH ,so everything works as it is should. No more changing AP modes during flights, as I run mainly FBW when I am cruising to a destination and RTH for the long trip home.

thanks for the idea

Brett

[Gary Evans]

This is how I set it up. I wrote it down incase I forget and though i'd post it here as it's a fairly common tx.

-------------
Return to Home (RTH) Activation Switch Setup
This will setup switch A to turn ON autopilot when in the up position
To get the 110% level required to reliably turn on RTH, 2 Program Mixes must be setup on the switch you use to activate RTH.

1. Press Model/Page
2. Press Model/Page again
3. Press ^Up arrow
4. Set rate to -100% (or + 100% depending if your throttle is not reversed)
5. Press the Down arrow.
Confirm and set the following:
MIX: OFF (or on if switch A is on)
MAS: OFST
SLV: THRO
LINK: OFF
SW: A (or the switch you want to use to control RTH)
POSI: Up (or down if you want the down position to activate RTH)

6. Repeat step 3-5 using Program Mix 2 instead of Mix 1. Set mix 2 exactly the same as mix 1.
------------------------------------------

Recently I had an issue where I only had 1 mix set. It was not enough to activate RTH reliably. It would randomly turn on full throttle, RTH or quickly jump between the 2 which can be disturbing when you don't know the cause.

Is the 9C like the 7C in that programed mix isn't available beyond 100%? My DX7 can go over 100% and I use 110% to trigger RTH with a switch.
On a newly acquired 7C I was wondering how that was going to work. By setting up two identical programed mixes of 100% on a switch are you saying it doubles the throttle from 100 to 200%?

[martinv]

Is the 9C like the 7C in that programed mix isn't available beyond 100%? My DX7 can go over 100% and I use 110% to trigger RTH with a switch.
On a newly acquired 7C I was wondering how that was going to work. By setting up two identical programed mixes of 100% on a switch are you saying it doubles the throttle from 100 to 200%?

Correct in that you can't adjust 1 mix to over 100% on the 9C (as far as i'm aware). I think 110% must be an absolute limit of a channels output pulse length, so setting 2 mixes at 100% gives you 110%.

Correction:
UPDATE 3-7-11: I discovered 2 mixes are required to completely bypass the trottle stick control. If you only setup 1 mix, the throttle stick will still have some effect on the throttle channel output. Previously I assumed the 2 mixes were increasing the throttle pulse length. On measuring it with an oscilloscope I found this was not the case, however 2 mixes are needed for the reason described in the first sentance.

[Gary Evans]

Thanks for the input!

[draconis]

So your using the throttle failsafe mode, correct?
also do you have the tx/rx failsafe set to 110% if link is lost?

[martinv]

So your using the throttle failsafe mode, correct?
also do you have the tx/rx failsafe set to 110% if link is lost?

By flipping the switch throttle is set to 110%, I don't actually move the trottle stick.

Yes if I power off my transmitter the receiver also puts out 110% to the throttle which also activates autopilot. The only difference is I cannot control my camera pan tilt or anything else I would add to spare channels.

The benefit of the switched RTH (with tx still on) is that you still can control the channels that are not routed through the RVOSD.

[draconis]

agreed, although my rx is set to go to idle on the throttle in failsafe, not 110. but not sure how to re-program that; so at this point i have to use glitch detection. so unfortunatly this wont meathod work for me today ;( but maybe soon though when i get a real radio