Do ProModeler servos work with my receiver?

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On firguring out if your receiver and our servos are compatible (short answer is, yes, they are).

Perhaps the most frequent question I handle at ProModeler is typified by . . .


Q.
Does my Futaba R3008SB receiver work with ProModeler servos?

A. Not just specifically Futaba, but substitute any brand like Jeti, Spektrum, Hitec, KO Propo, Graupner et al - any as you please - and the answer is always a variation on the theme. So here's how you can answer this for yourself.

Basically, it's down to confirming . . . 'Does your Futaba R3008SB work with PWM servos?' It's a yes or no question/answer.

So while I can definitely tell you yes, ProModeler servos work with your Futaba R300SB receiver, the purpose of this white paper isn't merely in responding to the overt question, but in providing answers to unasked question. Like, what makes one servo or receiver incompatible with another? Or, is one protocol better than the other? How can I always answer this for myself? We're going to teach you. That and more!

Real world math

In math, the common denominator was something useful for solving a division-question, remember? Turns out the common denominator concept is valid when dealing with servos and receivers brands/models/modes, too. In short, within the world of hobby-grade RF equipment and actuators (servos, typically but including winches, retracts, sequencing controllers, lighting, ESCs, and more), old-school PWM compatibility rules.

Thus, so as long as the receiver says it works with PWM servos, then all ProModeler and all servo-brands we know of (to include popular house brands, plus East Asian, and European aftermarket servos) will also work with your Futaba R3008SB receiver. That's the why behind your answer. PWM-compatibility.

Background

For your general store of knowledge, PWM (Pulse Width modulation) is the original standard of servo-control of modern-day digital radio control onboard systems. It's how receivers talked to servos. Still do! Note; modern day being defined as dating back 50-ish years to the early 1970s, if not earlier!

It all boils down to a 5V signal on the line ( a simple pulse of a repeating rate and duration measured in millisecond). The width of the pulse varies and along with 5-8VDC on the power leads is all it takes to make a servo function and go to a certain position. Change the duration (length in time) of the pulse and servo moves to another position. 3-wires - that's it - dirt simple!

Bottom line? Not only is PWM well established, but proponents of serial communication protocols haven't been able to make an airtight case against continued PWM-use. Serial protocols boil down to 1s and 0s instead of simple pulses.

Digital

1s and 0s means digital complexity. Not much but still requires actual intelligence. More costly. More complex, also because there's more to go wrong. More later.

Anyway, serial protocols haven't beat out PWM for lack of trying because decades after the introductions of various serial protocols, PWM is still the king. PWM is THE industry standard. After all, just because something is old (and PWM is the granddaddy) doesn't make it bad.

Doesn't an axe still looks like an axe despite the passage of thousand of years? Will a bronze-age axe not still cut down a tree? Same holds with digital-age standards like PWM because the receiver still tells a servo nothing more than . . . . rotate to X° of position. So the receiver says to the servo, go to a position and remain there until I tell you otherwise. And this is a servo's primary job, right?

More to the point, whether I tell you to stop in English, Spanish, or French doesn't matter as long as you understand it means, STOP, right? So PWM does just this. Has for a long time. And being an old established standard also means it's reliable. Note; established, as it turns out, is also good in terms of technological-costs. Anyway, it always comes down to money, doesn't it? More later

What I'm working toward is helping you realize - even without your being a college educated electronics engineer, or resorting to sophisticated propaganda and manipulation - the 'why' for serial protocols not supplanting PWM can be understood by everybody. It's so easy you don't need degrees because recognizing PWM's continued dominance is merely to do with interoperability, or more accurately, their lack thereof!

Put another way, what's wrong with the serial-protocols, all of them? It has nothing to do with their technical merits and everything to do with their inherent incompatibility. Incompatibility. It's their fundamental Achilles Heel.

Heck, even within Futaba lineup there are more than one serial-protocol. Ditto house brands like Spektrum have at least three different ones. Add to it standalone brands like Jeti, Graupner, ARS, et al have their flavors of serial bus and they're all incompatible with each other. Serial buses are (rather bizarrely if you think about it) little more than one-trick ponies designed to rope you into their way of doing things because all of the benefits can be obtained easily without giving up your autonomy to decide.

Recapping

The long and the short of it is, if your receiver says it works with PWM, then it's also interoperable with our servos (and everybody else's servos). Where you have to be careful is getting locked into some proprietary flavor of serial-protocol, or 1s and 0s.

- 1s and 0s are digital communication, exactly what a serial bus does

E.g. Futaba has S.Bus and S.Bus2 -  are more coming? Wouldn't surprise me. Similarly, Spektrum want to lock you into their sandbox but can't decide if they want you hogtied with DSM, DSM2, or DSMX, and again, are there more coming?

Jeti speaks several languages also like Jeti Box, PPM positive, PPM negative, EX Bus, or UDI. Nobody - not the aforementioned, or other RF-players like KO Propo, Graupner, Hitec, et al - can decide on even ONE serial protocol to move forward with against PWM! So why should you gamble your money when PWM works with everybody? Serious question!

Major point being, be damned careful what you wish for when it comes to the grass being greener on the other side of the fence (ditching PWM for serial). Especially as the case can be readily made for the converse . . . servos don't actually need to be serial instead of PWM. Nope, not at all.

Why paying protection wasn't a racket invented by the Mafia!

So basically, the only thing standing between you and getting bent over vice what-you-pay-versus-what-you-get in the servo-world are independents like us - ProModeler, Savox, MKS, et al. Meaning folks offering top notch quality and using the ubiquitous PWM standard.

Anyway, be careful what you wish for is my best advice because serial protocols have their place - but - they're not the be-all-end-all of intra-model communication.

Serial buses and complex models

For example, it's only within complex models (the only place serial-protocols even begin to make a little bit of sense), like a model jet with 18 servos versus a sport, 3D model, or helicopter with 3-5 servos, is there an argument to be made for serial bus. However, even then there are alternative solutions to the various incompatible serial-protocols. Readily available solutions that obviate the entire need for serial protocols . . . alternatives making serial protocols altogether superfluous! Not kidding.

'Box' systems for power and control

Spend $1000 for a model and you'll meet up with proponents of complexities I call box systems and power expanders of various sorts. Some with gyros, redundant power, and electronic switches adding to their complexity.

These, usually incorporate power distribution and basically obviate the entire argument in favor of serial buses in the first place! What's nice is you either use PWM or a serial bus to inter-connect the receiver to the box. Only good use I see for serial protocols at all. Otherwise? Nope.

This, because in addition to transporting a signal (one wire in the 3-wire lead), servos require power (the other two wires in the 3-wire servo lead). So which language the receiver and the servo speak (PWM, or the many, many, many serial protocols) via the 3rd-lead . . . is practically immaterial, because you 'still' need three-wires no matter what, capisce?

When the enemy of my enemy is my friend

Look, let's be honest. The RF-manufacturers would love nothing better than to rope you back into their corral . . . the days of vertical integration. That's when opening one box meant you had everything you needed to outfit a model with remote control equipment.

To include all the equipment like;

  • transmitter
  • receiver
  • battery
  • on/off switch
  • four servos, plus
  • battery charger

. . . and for all the bits to be their brand is the obvious goal of a business. Yup, the good old days! Back when everything came with their name 'and' all the money went into their wallet. Heck, back then, incompatibility was relatively unsophisticated. Just meant the games they still play like with the little black Dupont connector.

I speak about how right now, today, this still means minor irritations like the little blade sticking up on Futaba servo connector. The bit on their plugs that keeps you from plugging them into a Spektrum receiver. So their desire to dominate customer-decisions manifests all the way down to tiny incompatibilities on the mechanical front. Good grief!

Electrically, via PWM, they all work with each other - but - I suspect they'd like to change the balance of power back to like they had it in the past (before 3rd party servo vendors arrived on the scene and broke the lock on owning your wallet). Hence their continued desperation to get buy-in regarding serial protocols. You buy in they hit the mother-load.

So on the mechanically front (with the small plastic blade sticking up which represents just a small bit of grit in your shoe) they show a lack of goodwill - the tip of the iceberg. The blade is a minor inconvenience resolved by force, but at heart, it means if they don't care about your convenience even in this tiny regard. The RF guys don't share your fundamental economic interests, either. Heads up!

Not to put too fine a point on it, but if they repeatedly prove by their actions they only care about themselves. Not just with mechanical incompatibilities, just what do you think this means the minute you have to buy your servos from them (because of electronic incompatibilities), also? Yup, means your wallet's health is toast! Understand now why your interests and ProModeler's are aligned? Just saying.

Also means you're united with the spirit of the likes of Savox, MKS, and even Futaba (electrically) by PWM. Makes who the enemy actually 'is' clear, too. Lack of compatibility. That's the only real enemy if we're going to use the war metaphor.

Really, incompatibility, the desire to dominate is an economic enemy to us all. Companies that value their interests above yours are the common enemy. Proof is they won't work on minute standards everybody would be the beneficiary like the servo connector.

Little known fact, we're fortunate these days in using the Dupont with 0.10" spacing (2.54mm pitch in other words) as a near universal standard connector. Back in the day, each manufacturer actually invented their own. For example, Mr. Kraft commissioned a fellow name of Joe Martin to design the Multicon 3-pin connector (a 4th pin was present but just to prevent inverted insertion). This meant servos from World Engines, Orbit, Proline, or EK Logictrol wouldn't interconnect at all so using a servo meant physically changing connectors.


On resolving minor irritants

Anyway, with regard to fundamental mechanical compatibility, if you don't mind carving on their connectors with an X-Acto with #11 blade (and hopefully without the production of too much blood on the floor because those things are sharp), then you can even use Futaba servos with other brand receivers. This, because as it turns out, even their pricey serial-protocol servos are PWM compatible! What a hoot. Anyway, their included instructions for the Futaba R3008SB says;

- It also includes both standard PWM output ports and S.BUS output ports

Programmability

Changing subjects, one claim they (RF and competing servo manufacturers) make is that there's some big benefit in programmable servos. Our view is this is bunk. Bunk because claims of programmability as a benefit with servos are worth zero.

This, because you can easily instruct the servo on a channel-by-channel basis, anyway. Hence the reason for the popularity of 16-32-channel radio systems for complex models. That, and programmable servos are generally slow.

Remember, the RF-guy's fundamental goal is to rope you in. Standards protect you. Be alert. Don't save you weren't warned. The mere fact 'I' have a dog in the hunt with regard to selling you a servo doesn't mean the warning isn't valid because our interests in this regard are perfectly aligned. Yours and theirs, not so much.

Poor them, and why it'd be funny if it weren't so sad

Unfortunately for them, since the advent of independent servo producers like us, the new frontier in terms of keeping you within their product range are the serial protocols. They want to persuade you theirs is what you can't live without.

Fundamental problem is, you can live without them. Quite easily, too. Funny how that works when they are so busy making life inconvenient for you, otherwise, eh?

Summary

Remember, everything is compatible with PWM and thus, everybody's receivers work with PWM-servos and even serial-servos work with PWM-receivers (meaning all brands of serial-protocol receiver). Checkmate to the idea of serial protocols in the minds of modelers other than fanboys.

Put another way, everything works with PWM - but - the various serial protocols don't even work within each brand! So you have not just Futaba's various serial protocols of the S.Bus flavor but variations meaning Jeti has theirs, as does JR, and house brands like Traxxas and Spektrum, too!

Knowing this, it means instead of trusting me to know whether XYZ-receiver is compatible, this can be determined merely by confirming (the Futaba 3008SB receiver in this instance), works with PWM servos. Knowing this always makes 'you' the expert in the relationship with others. You have the answer without needing to ask me, or anyone!

This seeming bit of trivial knowledge is a key step in being your own expert, a really professional modeler, because it's fundamental knowledge. Here's a bit more about PWM.

PWM - the special sauce

Ours, and all servos I know of, even the ones that are some flavor of serial bus work also work within the PWM system. Basically, nobody in the RF or accessory business (radio systems and servos business) is so shortsighted they're going to limit their product's compatibility. Take my meaning?

These guys fight peripherally with silly games like the black 3-pin connectors but they don't draw a line in the sand. So a tip for the future is this; PWM-compatibility always answers 'your' question, which is; 'Is my money locked up?" As long as the answer is PWM, then the answer is you're not boxed into someone else's corral.

So what's PWM mean? Pulse Width Modulation is so simple. It's electrically a burst of static, noise on a line similar to a light blinking on and off to semaphore information between ships at sea. How long the light stays on (the width of the pulse) before turning off tells the servo how far to rotate. That's it. That's all PWM does. The pulse's duration tells the servo its position. Our servos tell the servo to stay on position more than 300 times per second (technically 333HZ), which is why they're so strong in terms of holding a position.

The neutral position for the servo is about 1500ms. One extreme adds up to 500ms of duration and the other direction subtracts about 500ms, e.g. from 2000 down to 1000 (with 1500 being in the center). That, and nothing else!

Any questions? Reach out to me info@promodeler.com and I'll try to help.

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