Spektrum failsafes

[Chris Bott - Moderator]

Can anyone confirm the failsafe differences between different Spektrum receivers?

 

I believe that 6Ch and below Rx's only have failsafe on the throttle channel.

Do the 7Ch and above have settable failsafe on all channels?

 

I would like to know because I'm doing some rudder mixing into two throttle channels on a twin. With the Rx's I have, channels 5 and 6 that are feeding my esc's seem to "Hold" on loss of Tx signal.

 

Cheers

Chris 

[Chris Bott - Moderator]

It looks like the question should be:-  "Which Spektrum receivers support "Preset Failsafe" ?"

 

Does anyone have any idea? 

[Romeo Whisky]

Some on this forum have asserted that binding only stores the throttle setting as a "failsafe", but I have proved for myself that this is not so, and the Spektrum Manual specifically recommends that you REBIND the RX to the model memory AFTER you have set up the throws, servo centring etc.

Needless-to-say, when you first start to install the gear, you have to bind the receiver in order to do all the tweaking (servo direction, EPA, Sub-Trim etc).   I have had models which after doing all this would stall the aileron servos (for instance) at maximum deflection in the event of connecting battery before switching TX on, or losing signal by switching TX off first.

However, after rebinding, (with throttle set to zero of course), from then on, the servos remain at centre even in event of signal loss or powering up before TX is switch on.  Use AR500, 6100e and 6200 RXs and this applies to all of them.

However ... this may not be the same as what you mean by "setting a fail-safe on all channels" if by that you mean that you want the model to failsafe with some control surface deflection (control surfaces other than neutral - eg. to go into a turn).  As far as I am aware this is not possible.

[Chris Bott - Moderator]

Thanks Romeo.

 

Yes that's exactly what I want to do, set Ch5 and 6 to one end of travel, i.e throttle low on loss of signal.  I believe this is possible on most other makes of equipment (But may be mistaken).

 

[Chris Bott - Moderator]

It seems that some Spekky receivers have two failsafe modes.

1. SmartSafe whic operates as RW describes. This is the only failsafe available on many receivers.

2. Preset Failsafe. In this mode all control surface deflections that are held during binding are remembered as the failsafe positions.

 

All I need now is a list of receivers that have this facility.

 

PS Instructions for this are in the AR7100 manual Here 

[Tim Mackey]

Well all the ones I have up to and including AR7000 only move the throttle channel - all the rest just hold known last good.

6000, 500, 6100 (+ E), 7000 

Dont use any others Chris, except the orange clones which do the same.

[Chris Bott - Moderator]

Thanks Tim, I've been trying to go through the on line instruction books. This is very tedious, so instead I just sent Horizon an email with the same question.

 

To be honest I think it's very surprising that the majority of receivers only have the simple version of failsafe. It is probably sufficient for most models, but it would be nice if we had the choice at least. I bet we could come up with plenty of situations where we might prefer a control surface offset from central on loss of signal...

[Tim Mackey]

Well TBH I sometimes think they are more trouble than they are worth - the only model of mine that I have lost due to radio issues in years was a PCM rx equipped one, on which I had set failsafe to apply a small amount of up elevator, and shut the throttle.

Upon experiencing a lock out, it worked perfectly, - the trouble was I was inverted at around 2 feet off the deck, and flat out at the time - complete write off.

After that, I never used PCM again ( I reckon a short "visible glitch" is perhaps better? ) and soon after, went 2.4Ghz anyway with no radio issues.

[Chris Bott - Moderator]

Hi Tim yes I do feel its all a bit academic  as loss of signal is so rare..

It's just not quite right that these motors will start up, even if they are stopped, if I suffer a loss of signal. Or if I switch the Tx off!)

 

Although I may have found a solution. See next post. 

[Chris Bott - Moderator]

Well here's what I found from the manuals before I gave up. If you check carefully there are subtle differences between seemingly similar receivers:- 

 

 

AAR500re"> SmartSafe onlyre"> Low throttle (set at binding)re"> Removes servo output pulses from all other channelsre">    

AR6110re"> SmartSafe onlyre"> Low throttle (set at binding)re"> Removes servo output pulses from all other channelsre">   

AR6110/e SmartSafe onlyre"> Low throttle (set at binding)re"> Removes servo output pulses from all other channelsre">   

AR6200re"> SmartSafe onlyre"> Low throttle (set at binding)re"> Holds all other channels at last commandre">   

AR7100re"> Preset Failsafe onlyre"> Preset Failsafe on all channelsre">   

AR7000re"> SmartSafe onlyre"> Low throttle (set at binding)re"> Holds all other channels at last commandre">   

AR6255re"> Smartsafe and Preset re"> SmartsaFe as AR7000.re"> Preset as AR7100re">   

AR7600re"> SmartSafe only

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[Chris Bott - Moderator]

sorry about the re">  all over the above. I'm pasting from Notepad. This must be another of the little quirks we love about this forum

[Chris Bott - Moderator]

Now, the good thing is, I can use an AR500. Assuming it does what they say. This way, on loss of signal the outputs will be lost, from this, my ESC's will stop the motors.

 

I'll do some tests and maybe swap some Rx's between models. 

 

mmmm, that will mean using throttle as one of my er... throttle channels. That's different to what I'm doing now. But should still work. 

Edited By Chris Bott on 15/11/2010 16:31:22

[Paul Newell 2]

I have a number of receivers all of which are used with a JR DSX9 Tx in glider mode.

 

Of my receivers the following have Smartsafe only

AR500

AR6200

AR6250 (obsolete)

AR7600

AR8000

 

The AR6255 has a fully programmable failsafe and should be rebound to the required settings after setting up/trimming a model.

[Paul Newell 2]

Just another point.

 

When binding a Tx to a model, not only do you have Model Match but the Tx also knows what TYPE OF RX it is bound to.  So if you take an existing program and bind it to a different type of Rx then it will no longer be bound to the original Rx.

[Chris Bott - Moderator]

Thanks Paul, I'll have to take that into account.

 

Your note about the AR6255 is correct, I've edited my table above to reflect this.

[Chris Bott - Moderator]

I've had a nice quick reply from Horizon. Great service as usual.

Hello Chris

> >Here is a list of receivers that have Preset Failsafe

6255
9000
9100
9200
9300
12000
12100

I've thanked them and asked if they have a list of SmartSafe only ones that remove all output pulses (except Throttle) on loss of signal.

[Chris Bott - Moderator]

Sorry to drag out an old thread but I've been having a good "play" with a Spektrum AR8000 and I've found a few surprises.

 

1. We generally refer to failsafe as the servo positions that the Rx moves the servos to after loosing a good signal.

2. This is different to the condition that the receiver is in at first switch on, until it connects correctly to the Tx. At this point for example, you may wish your retracts to stay down so that the plane doesn't collapse on the floor.

3. Some Spektrum Rx's are listed as having "SmartSafe" and some "Preset failsafe"

 

SmartSafe functions thus:-

When the Receiver is Powered On without a Transmitter Signal
If you turn on the R291 before you turn on the transmitter, SmartSafe prevents the
throttle from functioning and drives all other channels to their preset positions.

 

When there is a Loss of Signal in Flight

If the receiver loses the transmitter’s signal in flight, or any other time after a
successful connection has been made, SmartSafe sets the throttle to the position it
was in during the binding process. All other channels hold the positions they were in

at signal loss

 

Preset failsafe on the other hand,, does exactly what it says on the tin. You set all the servo positions that you want to happen, in the event of a failsafe.

 

The carbon fus Rx's seem to be listed as having Preset failsafe. As do some but by no means all of the high end ones. So I had a read of the instructions for a AR9200 Powersafe Evolution. Lo and behold that does either, depending how you set it up.

 

Confused? You will be!

 

I've just applied the instructions for binding the above Rx to my AR8000. Guess what? That too can be configured either way. Question is, why don't they tell us?

Edited By Chris Bott on 09/02/2012 14:02:09

[Pete B]

I agree, Chris, there's far too much left unsaid in Spekky manuals. Re the failsafe options, I peeled this, IIRC, from the interminable DX8 & DX10 thread on RCG a while back:

 

Hold Last Command
If you lose connection, all channels except for throttle channel hold last given command and the aircraft continues on its path. So, if you were turning when connection was lost, your aircraft would continue turning.
How to Program
1. Leave the bind plug in the bind port through the entire binding process.
2. Remove bind plug only after receiver connects to transmitter full throttle.

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 spoilers 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.

Furthermore, there's some useful information, particularly post #6, regarding the failsafe options when using the TM1000 in this thread, if you haven't already seen it.

 

I haven't really done much in this field myself yet - it's a 'round tuit' job, I'm afraid.......

Pete

[Ben B]

I don't understand the logic behind the "hold last command" style 'failsafe'. A brown-out is likely to occur when servo drain is the highest (IE when someone is doing some serious stick-banging) and when that's happening holding the last position is probably the worst thing to do. By definition servo drain is going to be highest when the control surfaces are heavily deflected. Returning to a neutral position with the throttle at idle would IMHO be the best option....

[Glyn R]

I have had an instance of mixed up failsafe. Last year I built and flew an Acrowot with an Irvine 53. using an AR500. This unfortunately met a sad end.

 

This year I built an electric Acrowot to replace it with a Turnigy 1100watt motor. I used the memory space in my DX6i which I had previously used with the glow model.

 

This meant I dind't have to set up the servos etc. However I found out on the field that the throttle failsafe was reversed. This was correct for the glow model but not for the Electric.

I had not rebound the Rx.

 

When a friend at the field turned off my Tx while I was recovering the model the Rx went failsafe which is the setting at which the model was originally bound. The throttle opened fully, luckily I was not near the prop and I managed to grab the model and disconnect the battery.

 

Moral

 

Always rebind a model after a rebuild. the failsafe settings are those at which the Rx was last bound.

[Tim Mackey]

And.... always turn a powered model off, before the Tx

[Glyn R]

Posted by Ben B on 09/02/2012 17:30:53:
I don't understand the logic behind the "hold last command" style 'failsafe'. A brown-out is likely to occur when servo drain is the highest (IE when someone is doing some serious stick-banging) and when that's happening holding the last position is probably the worst thing to do. By definition servo drain is going to be highest when the control surfaces are heavily deflected. Returning to a neutral position with the throttle at idle would IMHO be the best option....

I guess they think this is best for momentary loss of power.

[Glyn R]

Posted by Tim Mackey on 09/02/2012 18:42:39:
And.... always turn a powered model off, before the Tx

Glow motors don't restart Tim Electrics do.

 

Edited By Tim Mackey on 09/02/2012 19:28:38

[Tim Mackey]

Posted by Glyn R on 09/02/2012 18:50:35:

Posted by Ben B on 09/02/2012 17:30:53:
I don't understand the logic behind the "hold last command" style 'failsafe'. A brown-out is likely to occur when servo drain is the highest (IE when someone is doing some serious stick-banging) and when that's happening holding the last position is probably the worst thing to do. By definition servo drain is going to be highest when the control surfaces are heavily deflected. Returning to a neutral position with the throttle at idle would IMHO be the best option....

I guess they think this is best for momentary loss of power.

 

Brown outs and signal loss ( the only thing that activates failsafe ) are NOT connected at all.

[Tim Mackey]

Posted by Glyn R on 09/02/2012 18:52:28:

Posted by Tim Mackey on 09/02/2012 18:42:39:
And.... always turn a powered model off, before the Tx

Glow motors don't restart Tim Electrics do.

 

Edited By Tim Mackey on 09/02/2012 19:28:38

Not if the model has its power turned off they dont.

 

Look, its quite simple, any powered model should have its potential source of propulsion disconnected beofre the tx is switched off. In the case of an electric model that means disconnecting the flight battery, in the case of IC it means shutting the throttle completely to stop the engine.

It was always ( and still is actually ) the mantra that...

At the start, its tx on first, then rx. At the end.... its rx off then tx. This prevents the rx from possibly glitching/sending spurious uncommanded signals etc to the model in the absence of a valid tx signal.