FrSky Taranis - user chat

[Chris Bott - Moderator]

Hi Bob

I've been searching and just can't find it. But I recall some question about the frame rate of the pulses from the Sbus decoder. It may have been that they are at the fast rate that suits digital servos. But don't quote me, I haven't checked.

Having said that, I'm using mine with 2 analog flap servos, 2 analog aileron servos and some E-flite retracts with no issues at all.

I did go the lazy route and set mine to use channels 2, 5 & 6. But only because it was an existing model and the reason for use it to have a single servo lead between Fus and Wing.

I don't see why a particular channel would be different. I suspect it's more likely that your servo didn't like it?

[Chris Bott - Moderator]

OOH I may have found some info.

I found post #25289 here, with a PS that says P.s. It says in Aloft's description that it is compatible with digital and analog servos.

Going to Aloft's site though, that info appears to be different. So, have they updated the info since?

Aloft S.Bus decoder

Edited By Chris Bott - Moderator on 27/05/2014 12:04:33

[Bob Cotsford]

Thanks Chris, I saw product descriptions that stated analogue or digital, but not the short frame rate. I tried Emax ES08MA which most definitely didn't like it and showed their contempt by burning out the wiring harness back to the switch, and now I'm trying HS82MGs that I had lying around. It sounds from Aloft's description as though I need to swap out the channels I'm using for Sbus with something like flaps where I'm using Savox servos, or swap to a two receiver setup, which might not be a bad idea on a 30cc size model.

A South Herts twin on-board glow drive and the Lado retracts seem happy enough on S-bus - so far!

From the Aloft description:

"NOTE: Will pass the Sbus framerate to the servo (PWM) output. Typically this will be about a 9ms frame rate, these faster frame rates will work best with digital servos, though some analog servos appear to be OK."

[Bob Cotsford]

Last night I used Companion to juggle the channels in 'mixers' by copying and pasting to get the 4 Savox digital servos in the wings on sbus and the fussy Hitecs on ch 6 and 7 with retracts on 5 and glowswitch on 8. All very simple except for sub-trim and end points, there's no easy way to move those between channels so each field on each channel needs to be edited one at a time - it pays to duplicate the model first to keep as a reference when editing the new version

[Chris Anthony]

Thanks for the help with my binding issue chaps, tried it last night and it worked. I misinterpreted the instructions and didn't think the bridging method applied to me!

I'm looking to buy a 3D EPP profile plane to fly with my Taranis. This would ideally use a mirco RX, and presumably would have to be an FrSKY one. Has anyone tried to buy one of these before? Currently the only ones I can find are on eBay and need to be shipped over from Hong Kong. I don't want to be waiting that long!

Any recommendations?

Edited By Chris Anthony on 30/05/2014 13:12:13

[Chris Bott - Moderator]

Would one of these do Chris? No telemetry but it's nice and small.

Click on the pic to go to the T9 website. They have a couple of small telemetry rx's too.

[Bob Cotsford]

The D4R's are good little receivers but might be overkill if you don't need full range and telemetry

[Chris Anthony]

Thanks, it's nice to find a site where FrSKY stuff is sold in the UK that isn't eBay.

[Eifion Herbert]

Does the X6R do receiver voltage telemetry? Mine doesn't seem to.

I've got an X8R in the Radian and an X6R in my Wot4 (yes silly I know but there's actually more room in the radian's fuse) on the Radian I get RSSI and Rx voltage displayed.

With the Wot4 I only get RSSI, Rx voltage is showing as 0v. They are both being fed from the BEC on their ESCs into channel 1. and the Taranis' internal RF module is in D16 mode for both.

[Chris Bott - Moderator]

Hi Eifion, yes I'm sure it does.

Without looking I seem to remember one of those little black links in the back of the Rx, almost hidden. I'm fairly sure that supplies the Rx volts sensor with Rx volts.

[Eifion Herbert]

The only thing on the X6R are the 6 channel outputs, S.Bus and Smart Port. On the X8R I have a vario plugged into Smart Port, but even if I unplug the sensor I still get RX voltage, the only things plugged into it are the ESC in channel 1, and the rudder / elevator servos in channel 2 / 3.

The X6R doesn't give me anything on RX voltage, even though I am getting RSSI data showing that 2 - way communication between the RX and TX is working. Now I'm not massively fussed about knowing the Rx voltage at any time, it just bugs me if it's meant to, and it doesn't, it means I've got something not set up right.

[Former Member]

[This posting has been removed]

[Eifion Herbert]

Ha, you're quite correct Andrew, set the A1 voltage on the telemetry page and there it was. I don't remember setting it on any of my other models tho - only have three on there so far. I had created the Radian and Alula models on the Taranis itself, whereas the Wot 4 I'd made in C9X and transferred it, maybe that's where the difference was.

Thanks for the pointer!

Eifion

[andyh]

ok, possible dumbass question(s) alert ...

I'd always assumed that the BEC would provide a pretty-much constant voltage to the Rx (whilst the LiPo had above-flat voltage at least). is this actually not the case & BEC-supplied voltage will drop as the LiPo discharges?

ie you can infer some degree of LiPo state from voltage supplied to the Rx? ie #2 you don't need direct LiPo voltage monitoring to get a reasonable measure of discharge status?

many thanks

Andy

[Biggles' Elder Brother - Moderator]

If the BEC is operating as voltage regulator then you should see a pretty constant Rx voltage until the Lipo is almost discharged - a place you should of course not be taking it too!

So in effect I think the answer to question two is "no" - because by the time you are picking up low Rx voltage supplied by a BEC the Lipo is so close to its final throes it will be blindingly obvious to you anyway! Its a bit like a "low oil pressure warning light" on a car dashboard - by the time its on its too late!

Of course as a check on wirng resistance/poor connections etc its still valid. And for IC and those electic models using a separate Rx supply its invaluable.

BEB

[andyh]

roger, thanks BEB

what would be the recommended sensor for LiPo voltage? I'm assuming something connecting to the balance plug rather than inline on the power connection? I'm looking to use X6R/X8R Rx's if that makes a difference

thanks

Andy

[David...]

I use these, their great: **LINK**

Connects to the balance port.

[Biggles' Elder Brother - Moderator]

Well if what you really want to do is monitor your power Lipo I wouldn't use a voltage sensor at all. I use a current sensor. The current sensor sits between the battery and the motor and obviously measures the current flowing through it. But it also does three other things;

1. It measures the battery voltage at the same time. This means that it can,,,

2. Work out the instainteous power in Watts - very handy you don't need to use a Watt meter and you can get the reading in the air as opposed to one the ground!

3 Best of all it can integrate the current, so it can work out exactly how many mAh have been taken out of the battery. This is a much better measurement of battery use than monitoring the voltage. You can then set audio messages for say 2/3 capacity used up and 3/4 capacity used up. Effectively an electrical fuel gauge.

For up to 40A this Smartport sensor costs just £12 - a 100A version is available but it is not Smartport, a Smartport 100A sensor is expected very soon. You can use the non-Smartport one, but you need to connect it either via a hub or a vario.

BEB

Edited By Biggles' Elder Brother - Moderator on 31/05/2014 22:19:26

[Eifion Herbert]

Why does the range need to be set to 13.2 specifically? It works - but I'm the type that likes to know why things work...

[Biggles' Elder Brother - Moderator]

Oh now that's a good question Eifion!

The way A1 works is that the voltage is scaled using the relationship 3.3/(divider ratio). For an X receiver the divider ratio is 1:4 so we have to set the scale at 4 x 3.3 - that's 13.2.

This divider ratio is different for other Rx ranges

BEB

[andyh]

Posted by Biggles' Elder Brother - Moderator on 31/05/2014 22:18:06:

Well if what you really want to do is monitor your power Lipo I wouldn't use a voltage sensor at all. I use a current sensor. The current sensor sits between the battery and the motor and obviously measures the current flowing through it. But it also does three other things;

1. It measures the battery voltage at the same time. This means that it can,,,

2. Work out the instainteous power in Watts - very handy you don't need to use a Watt meter and you can get the reading in the air as opposed to one the ground!

3 Best of all it can integrate the current, so it can work out exactly how many mAh have been taken out of the battery. This is a much better measurement of battery use than monitoring the voltage. You can then set audio messages for say 2/3 capacity used up and 3/4 capacity used up. Effectively an electrical fuel gauge.

For up to 40A this Smartport sensor costs just £12 - a 100A version is available but it is not Smartport, a Smartport 100A sensor is expected very soon. You can use the non-Smartport one, but you need to connect it either via a hub or a vario.

BEB

I was expecting someone to suggest this

I totally get that integrating current over time is very cool - I'd had the same thought myself, before I even knew that any Telemetry Tx could do it

I just think that maybe it's a hammer to crack a nut as the residual voltage has a pretty well-known correlation to residual charge

as I vaguely recall (from 20+ years ago), don't you always, by definition of the integral, lose the start point?

therefore isn't it safer to monitor voltage? what if you, by mistake, take off with a part-charged battery?

as an analogy, would you want the airliner you're flying in to be calculating its range by integrating its fuel-flow meters over time, or monitoring its fuel tanks' contents?

Andy

[Biggles' Elder Brother - Moderator]

Well on the airliner question - if we know the fill state of the tanks at the start it makes no difference. In fact integrating fuel usage is probably more accurate as measuring liquid flow is a lot easier than measuring liquid level in a moving tank - which incidentally you can only do by integrating the level readings anyway to form a "moving average" so as to smooth out sloshing effects, so your level reading is integrated anyway!

"Losing the start point" surely isn't really an issue for us - for two reasons:

1. We (well I) don't fly with part charged batteries. So I know "fill state" at zero time. And if I also check my batteries on landing I can pick up if their capacity is falling off due to age and so adjust my thresholds accordingly.

2. We're using it to trigger an alarm with presumably a reasonable safety margin. I certainly don't fly my Lipos down to "the dregs"! So it hardly matters if when it tells me I've used 66% of my batteries capacity if the true situation is that I've used 68% of my battery. I'm just not cutting it that fine.

These, together with the ability to monitor and log in-flight power, make it a current sensor by preference every time for me. But of course its a personal choice.

BEB

PS The cost difference between the two is next to nothing!

Edited By Biggles' Elder Brother - Moderator on 31/05/2014 23:49:51

[Chris Bott - Moderator]

The beauty of the current detector is that you also get voltage. So by all means set a voltage alarm. Then if you do use a part charged or ageing lipo, you have the indication you should land. However if you rely on voltage only, you tend to get the alarm every time you open the throttle wide, especially as the battery gets lower.

With the mAh reading though, you can have the Tx speak to tell you how much juice you've used, whenever you wish. If you get a voltage alarm earlier than you expected, then you know you have something to investigate.

[Brian Lambert]

Has anyone found any problems with opentx 2.0 on Taranis?

[Masher]

Can someone clarify the standard telemetry features with Taranis please? With the X8R receiver the way I read the spec is that RSSI is provided but I am not clear on Rx supply voltage?

Thanks