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Author Topic: Failsafe to zero on three channels required  (Read 892 times)

Big E

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Failsafe to zero on three channels required
« on: October 27, 2020, 04:50:36 pm »

I am seeking some help on sourcing a receiver which will failsafe to zero on at least three channels, not just to 'maintain position' but to 'default to zero'.  I have a three motor boat (1/12 Vosper MTB, brushless) with three independent ESCs.  To make the thing turn, I use a mixer on the two outer motors which is biased by the rudder control, a fairly standard setup.  Now, this is fine with a standard transmitter/receiver set up as a standard receiver failsafe usually defaults to zero only on a single channel (throttle of course, CH3), the other channels (steering or whatever) usually defaulting to 'position hold' in the event of signal failure.   And here's the crunch.
I am converting to OpenTX (It's the future, it is truly a game-changer) so I will be able to control all three motors independent of one another on a single stick by using three channels.  No problem, I can use up to 36 channels if I want to and  by judicious mixing within the transmitter I can have spin on the spot, have outer motor throttle control biased by the rudder and just about everything in between including playing the National Anthem when coming alongside!  (I strongly recommend you all look at OpenTX Companion, it is a free download, it is self-explanatory and it has its own simulator, so you can try it out in the comfort of your own home for nothing.  What's not to like?)
The crunch comes when you have to programme in a failsafe on the receiver.  The middle motor on my model will be governed by the throttle channel, so when the signal fails the middle motor throttle will default to zero, but the outer two motors will be plugged into channels 5 and 6, so in the event of signal failure with a normal receiver, they will hold throttle position, which could be wide open!
What I need is a 4 channel (minimum) receiver which can be set up to default to zero on a least three channels.  2.4 gHz, DSM/DSMX and NOT Futaba.  Has anyone any suggestions please, I can't be the first to meet this problem surely?


Chris.
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tsenecal

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Re: Failsafe to zero on three channels required
« Reply #1 on: October 27, 2020, 05:26:08 pm »

opentx allows you to set the failsafe of every single channel individually.  whatever the three channels are that you use for your throttle, those three channels can failsafe to "zero".

https://www.youtube.com/watch?v=9bz6Vg1yv88
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Big E

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Re: Failsafe to zero on three channels required
« Reply #2 on: October 27, 2020, 05:58:48 pm »

What a fast response, thanks.  In the interim, I have found that by removing the bind plug on a live RX before binding the tx with all channels in the zero position, the binding routine works as normal and on loss of signal, the rx defaults ALL channels to zero.  Exactly what I wanted, failsafe achieved.  Have a look at https://www.youtube.com/watch?v=LDMuYLPkgzE
Now, I agree that OpenTX does allow you to pre-programme failsafe, but only on certain receivers apparently.  For example, my Radiomaster TX16S does not display the failsafe settings at all, but I know that some do.  Quite why mine doesn't I haven't been able to find out.....yet.  It should display in 'model setup' at the bottom of the 'Internal RF' list, but it ain't there.  Maybe something to do with choice of RX, I don't know.
Strange but true.


Regards,  Chris.
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tsenecal

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Re: Failsafe to zero on three channels required
« Reply #3 on: October 27, 2020, 09:04:17 pm »

it has 100% to do with what the receiver is.  not all receivers are created equal.

i come from the olden days when the only transmitters with OpenTX were the frsky models.  frsky X series, D series and R series receivers fully support the "custom" failsafe setup.
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spearfish99

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Re: Failsafe to zero on three channels required
« Reply #4 on: October 27, 2020, 11:59:26 pm »

Some of the Orange rx's allow failsafe on all channels if the Tx's   failsafe  function can be disabled, at least on its Futaba FASST versions.

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