Failsafe programming

[Chris Bradbury]

Hi folks,

I'm using a DSX9 mkII and an AR9000 and am trying to program a custom failsafe mode, but can't get it to do anything else than shut the throttle and hold on all other channels.

What I want to achieve is this. Throttle to zero and Aux2 to zero (it is on a permanent mix from the throttle) all other channels can hold.

The reason being, I have a quad engined plane, with two motors running off the throttle channel on a y-lead and two off the Aux2 channel, running on a mix from the throttle. The issue being that when I test the failsafe, the motors on Aux2 stay at the power they were set at, which is not good enough.

I have RTFM, which states a transmitter setting to do this, but I have discovered this no longer exists on the 2.4ghz units, it's just been left in the manual, useful aye? An online search states to start the binding process as normal, but remove the binding plug once the LED's are flashing before switching on the Tx, but before I try this, has anyone else done it? Don't fancy trying something not in the manual until I know it's safe.

[Dave Smith]

Hi Chris,

I'm in a similar situation to yourself in having a four engined Lancaster. Only difference being I'm using AUX1 and AUX2 mixed with the throttle to control the engines, the engines are plugged into the two Aux channels leaving the throttle channel unused. If any one of the four engines fail I can switch off either the inner or the outer pair.

Setup for fail safe was as per the manual and worked a treat on my DX8 2.4GHz Tx and AR8000 by removing the bind plug whilst the lights flash and before turning on the transmitter and carrying out binding.

I know my setup is not not exactly the same as yours, but I'm guessing it should work and no harm should come from trying it.

[Rob Buckley]

The failsafe on Spektrum should be whatever position the sticks are at when the TX/RX are bound. If the other throttles are on a slave mix to the throttle, they should all be at idle when the throttle stick is at idle.

If you set all the channels how you want them, then re-bind the RX normally & complete the binding process, when the TX is turned off all the channels should go to their 'bound' failsafe positions.

[Chris Bradbury]

Thanks guys.

Rob I agree with you for Spectrum as my early DX6i was exactly that, but the DSX9 is a JR radio, it just uses a Spektrum frequency module, hence you can use Spektrum receivers, but the failsafe works slightly differently.

Dave, does it state to remove the bind plug like that in the DX8 manual?

I must say I'm quite shocked that in this day and age, (the court case generation) that a company like JR are still printing a manual that is out of date and wrong. I've done some more digging since I posted earlier and it appears they have added an amendment to the downloadable online version of the manual, which states that the JR RD921 9ch receiver will work how Rob says, but still no mention on Spektrum ones. My manual was as much use as a chocolate tea pot for this.

I've bound dozens of models to it, but never more than a twin, so never put a pair of motors on another channel until now, so never had this issue. The default setting with Spektrum receivers is to only shut the throttle and leave everything else on hold, despite what you do with this sticks mid bind or any mixes you might have.

I shall try the trick of removing the bind plug mid bind as Dave says, as I've seen this idea described in a couple of places now and hope it does the trick. At 11kg for the model, I'm not taking any risks.

[Dave Smith]

Hi Chris,

From the DX8 manual page 12, extract below
--------------------------------------------------quote----
Preset Failsafe
If the signal is lost, all channels are driven to their failsafe position set during binding.

Preset Failsafe is ideal for sailplanes, as spoliers can be deployed during loss of signal, preventing a flyaway.
how To Program

1. Insert the bind plug and power on the receiver.
2. When the receiver LEDs blink indicating bind mode, remove bind plug before binding the transmitter to the receiver.
3. LED lights will continue to blink.
4. Move transmitter’s control sticks and switches to the desired Preset Failsafe positions then turn it on in bind mode.
5. The system should connect in less than 15 seconds.

NOTICE: Failsafe features vary according to receiver, so if using a receiver other than the AR8000, consult your receiver’s instructions for the failsafes that apply.
---unquote--------------------------------------------------


Even though your transmitter is a JR radio the fail safe is a receiver side function when loss of signal occurs. As long as the receiver can correctly receive signals from the transmitter to control the servo channels in normal flying mode then the preset fail safe mode can be set, the type of transmitter is therefore irrelevant.

Obviously, the receiver must be capable of being programmed this way and the AR9000 can be. If you look in it's manual under the section Programming Preset Failsafe it gives the same basic information about removing the bind plug BEFORE binding.

A simple safe test would be to go through the above process and preset one of the other elevator, aileron or rudder channels to something other than mid-stick position instead of playing with the throttle channel. After completing the binding process you could then switch the transmitter off and when the receiver loses the signal it will move the selected channel to the previously set position.Switch the transmitter back on and once a signal has been re-established by receiver the selected channel will move back to it's mid-stick position.

[Chris Bradbury]

Many thanks Dave, I shall give it a go.

[Rob Buckley]

That'll teach me to do more manual reading! I looked in the manual for one of my AR9100's, and it gives the two failsafe types as Dave describes.

The same procedure is in the AR9000 manual here http://www.spektrumrc.com/ProdInfo/Files/SPMAR9000.pdf

[Chris Bradbury]

Thanks Rob, I must confess although I went straight to the manual for the transmitter, I never thought about looking for a receiver manual.

[Rob Buckley]

Chris, it makes sense that the failsafe is all programmed & set in the receiver, as the TX could be a Spektrum TX or a module.

It also reinforces the importance of re-binding & setting the failsafe as the last job AFTER all the radio setup & programming as been completed. Only then can you be sure that the failsafe all works the right way & not to full throttle!