Arming an ESC

[Ron]

Getting a fit foxed.

I've just got to checking the ESC and motor direction with the Squall build/assembly.

Now the instructions with the Squall say turn on the ESC/Rx with the throttle at minimum and the ESC should give (actually it says WILL give) three short beeps to confirm arming. The throttle can then be slowly advanced and the prop will start to turn.
Fair enough.

The problem is... whatever settings I put on the Tx the ESC stays silent.

The Tx is a Cockpit CX.
On that there are several servo/throttle settings.
First, you can set which direction you want the throttle to work - minimum towards you or away.
I've got it set towards me, so opening the throttle means pushing it away.

Next there is servo reverse.
Changing that just makes everything work backwards.
You'd think this was the same as the throttle stick direction wouldn't you? But no.
There's a throttle check system that checks you've got it at minimum at start up, and that is relative to the stick setting, not the servo reverse.

Then there is the servo travel setting.
This can be set to +-110% for each direction.
So you can have minimum throttle (or any servo) at -110% and max at +110% (or any other value).
The complication with this is that if you set it the other way around (min to +110% and max to -110%) the servo works the other way, just like servo reverse.
Which way the throttle should be set I really don't know, and there's no guidance in the Tx book.

So far I've tried many of the possible combinations of all the above, and have yet to get a peep out of the ESC, except one time - that was when nothing happened on switch-on (as usual), so I moved the throttle stick a bit. (only a bit, honest). The ESC did three quick beeps and started the motor at full throttle.
Had to stop the Squall getting away off the bench.

I've been sitting here playing with the Tx and Rx with an ordinary servo in the throttle (4) slot and trying to make sense of it.
Unsuccessfully.

It would be a great help if anyone could say which way a servo should move when plugged into the throttle slot.
Also - a previous ESC I had needed first initialisation by setting the throttle to max, turning on, then moving it to min, whereupon it would beep.
But there's nothing like that in the Squall instructions.

So please help before they come to take me away  :twisted:  :twisted:

Ron

[billscottni]

best bet would be to try and determine the make/model of the esc and get the instructions.

You could also have a dead esc!

[Happy Days]

Don’t panic!!…………The answer is……..servo reverse. :wink:

Reverse the throttle servo operation on your TX Ron and all will be well.

Well, I’m very confident it will. :roll:

You could try leaving the situation as it is and move the stick furthest away from you, (Full throttle in powered plane mode, or zero airbrake in glider mode.) Then connect the battery, if the motor arms, by giving three bleeps, you’ll find that by moving the throttle stick towards you the motor should spin up.)
'Servo reverse' should then bring things into line with normal convention.


So, you’ll soon be maidening her will you??

Keith

[Happy Days]

Er,….just a thought Ron, you have got your Tx set to “ACRO” and not “Glider” haven’t you? :wink:

Yes,….I knew you had really,……silly me :oops:  :oops:

[Ron]

Thanks for all the replies.

Got it sorted      
Servo reverse - not directly.
Stick reverse - not directly.
It was all to do with the strange percentage settings for stick/servo movement.
On normal servos it's fairly obvious. The centre is centre, and one way is plus and the other way is minus.
But for throttle.... stick to minimum, whichever way you've chosen on a different menu, is equivalent to one end or the other on a normal servo.
It's not zero or 'in the middle'.
And it seems that the throttle has to be set for zero at the minimum end, going to -110% at the wide open end, with centre travel being -50%.

Now exactly why it's zero going to minus, and not zero going to plus is beyond me.

So the problem was that because the throttle, in common with all the other servos, was set to zero at centre travel, the ECS never saw zero, so would not initialise.

The only 'issue' (as they call problems these days   ) is that the Squall book says it should be set to 120% and the Cockpit SX only allows 110%.
Does this mean I can't get full power I wonder? :?:

So thanks again.

Ron

[Happy Days]

Hhmmm, I down loaded a copy of the Cockpit manual and skimped through it but didn’t read anything about that. :!:
Curious. :?:

Oh well, you got it going that’s the main thing ……………….Off to a wide open space today are we?

K.

[Ron]

Hi Keith,

No there's nothing in the manual about it.
In fact, although the manual reads quite well, it is quite confusing on many related points.
In fact I've just found even more about the throttle settings.
There are three ways of reversing the throw of the throttle, each one affecting the others.
And the ESC sees zero or anything more negative than that as true zero.
So to get the whole setup working, with minimum throttle towards the operator, you have to disable the well intentioned 'throttle check' that works on Tx turn-on to make sure you've got the throttle at minimum.
Me thinks there are a few bugs in the software.

But.... OK. Got it working anyway.  

There are a few more things to glue on yet.
And I may just wait until the wind drops below 27kts (wot it is now).

Also got a few domestic duties to perform (jobs) now the rain has stopped.

Ron

[Aidan]

Hi Ron,

I wouldn't worry too much about 120% being mentioned in the manual to get full throttle. That's entirely dependent on the brand of TX. They all use pretty much the same signal ranges but they use different size chunks from the middle of this range to define as their +/-100% for your travel settings.
So for example if you start with servo movements set to 100% on a JR system I think it's possible to increase these to 125% and get 25% extra servo travel. So 100% is not really 100%. Futaba and other systems all leave differnet amounts of movement available beyond what they call 100%. However, if I rmember correctly Multiplex actually use +/-100% to describe the entire signal range. If so then +/-100% on Multiplex will give you the same servo movement (or throttle range) as +/-125% on JR and say 130%, or whatever, on Futaba, etc...
If +/-100% on Mulitplex is equal to the full signal range then the 10% is just the available trim (you can get more but on I think on the EVO you have to add it a max of 10% at a time) but does not give you extra total movement.
The Multiplex EVO software automatically sets throttle to 30% at minimum stick as the default idle setting, I reckon the Cockipit is the same. The throttle cut function sets throttle to 0%. Any ESC I've used (mostly Hacker and Castle with a few others thrown in) will happily arm with the 30% minimum. The throttle check function just stops the radio transmitting until you've zero'd the ESC so it shouldn't effect anything. You'll always have the transmitter on before you connect your cells to your ESC.

I've recently started using a 2 position switch on my EVO instead of the push button to activate the throttle-cut function. I connect the ESC to the cells with the throttle-cut on so there's no danger of knocking the throttle stick by accident and being hit by the prop. I've started the motor by accident a few times before, usually while putting a neckstrap on or carrying the transmitter to the flightline but always with small planes and I've been lucky so far. Bigger electrics are affordable now so it's time to be a bit more cautious! With glow or petrol the prop stops when it hits something. Electrics keep going so I think they're potentially much more dangerous.

With my setup, if the throttle is live the prop is turning at idle (could change this for gliders if you wanted - or just use the cut switch to fold the prop). If I hit throttle-cut the prop stops moving and the throttle stick is dead. Good safety setup I think.

Aidan

[Ron]

Hi Aidan,

I have to admit the 'more than 100%' thing was getting a bit annoying, me being a pedantic type.
100% of what I kept asking myself.

And the 30% min throttle does seem to be right (of course), as now I've got it working the actual throttle doesn't have any effect until about 30% stick travel.

Your idea of using a switch on the throttle cut is a really good one.
OK, on this EDF unit there's no chance of personal injury, and the ESC won't arm until the throttle is at zero.
But on exposed prop aircraft it can be dodgy.
As you say, electrics don't stop.

Wouldn't it be nice if there was some sort of standard - ha, ha. :lol:  :lol:

Ron

[Happy Days]

I’m sure I read somewhere that servo’s are only supposed to move a certain number of degrees either way. (I think it was about 60deg.)The idea of using the Tx to push the servo to (say) 110% of travel is to make the servo go beyond it’s normal level of travel. That’s why in the Tx manuals it refers to 110 or 120% of travel. Although I'm not sure if I've got that right. :?:

I’ve just spent half an hour trying to find that info again, but to no avail. :!:

Perhaps I dreamt it! I do a lot of that these days,………Dreaming.
I had a wonderful dream the other night, she was 6ft 2 with long dark hair and …………….Er …..okay, I know….. Too Much Information. :oops:

Keith

[Ron]

Well, you would think there was a vague standard of some sort for servo movement.
Or is that wishful thinking?
If that is the case then the servo specs should say what it is.
Even if it's just a 'recommended maximum' type of thing.
But really it should be relative to the Rx output at 'standard' signal conditions.

How any or all of that might apply to ESCs is another subject entirely.

And there are boat ESCs that have, presumably, off in the centre, and reverse the other way.
Sorry, astern...

Ron

[Happy Days]

Just been comparing the spec of a number of different servos. In all cases, when quoting the speed of the servo the specification refers to the amount of time for the servo to move 60 degrees.

I therefore believe that what I read before probably was correct. That the “Standard”, amount of movement of a servo arm is 60degrees. :wink:

Although this is only my speculation, it seems to me that this amount of movement equals the “100%” quoted on Tx’s

Well, it seems rational at least! All interesting stuff you know :?:

K.

[Ron]

That's interesting.
So the next project is: Measure some servo angles with the Tx set to 100%.
Across a range of servos and Txs of course.

Ron

[Aidan]

There is a standard but it's based on the signal frequency not the movement of the servo. There's a standard centre position which I think all radio brands use (including Multiplex in UNI mode. In MPX mode there's a 9% difference) Different servos may have different max deflections bu the signal range that produces them should be pretty much standard. So full travel on one servo will happen with the same signal input as produces full travel on any another servo. The % thing is just a convention. As far as I'm concerned 100% servo travel is the full range of motion available. However JR, Futaba and probably most radio brands don't treat it that way. They take, say, +/-80% of the actual available servo travel and call that +/-"100%" on their tranmitters. This means if you set up your plane using "100%" throws and then decide you need more you can have another 25% because you weren't really using 100% to start with. As I mentioned earlier , I believe multiplex mean it when they say 100%. If I remember correctly anything over 100% on a Multiplex radio only has an effect if it's feeding into a mixer or is the result of a trim adjustment and it's shifting the relationship to the stick position but not increasing the available throw.....I might be wrong about that last bit!
I recently got a JETIbox and have started using it to set servo centres and check available deflections - very convenient when setting up a model. It allows you control the actual signal value throughout the full range. I can take a look tomorrow evening and see what the actual range is and where the centrepoint lies. I think the standard is 1500ms with a range of +/-500ms but I'm not sure. It might be 1600ms.

[Happy Days]

Yea’ I’ve just been reading through my Futaba manual. (All 119 pages of it! :!: )

When referring to the amounts of servo movements available with this Tx (10CG) it says;

• Ranges from 0% (no servo movement at all) to 140%. At a 100% setting, the
throw of the servo is approximately 40° for channels 1-4 and approximately
55° for channels 5-8.
• Reducing the percentage settings reduces the total servo throw in that direction.

That would seem to concur with what you’re saying Aidan. I can’t for the life of me understand why 100% isn’t 100% movement.
And as for why “100%” movement should be different for some channels and not others completely baffles’ me!

It’s never really bothered me. I’ve just set the movements up to the amount I wanted. But looking at the matter from a broader perspective it does seem a somewhat ridiculous way to run a hobby.


Keith