Go Back  RCU Forums > RC Airplanes > RC Jets
Reload this Page >

15 PWM channels + telemetry out of a single R7008SB Futaba receiver

RC Jets Discuss RC jets in this forum plus rc turbines and ducted fan power systems

15 PWM channels + telemetry out of a single R7008SB Futaba receiver

Reply

Old 12-14-2016, 11:49 AM
  #26  
dbsonic
My Feedback: (3)
 
dbsonic's Avatar
 
Join Date: Oct 2005
Location: san jose, CA
Posts: 861
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Great thread. there is a lot of interesting things out there. While I may not use in a jet, I might in something else. And then with a good amount of testing in that platform may reconsider where else I might use it.

I remember the Eagle Tree Guardian was getting some bad press at one point. I called up the designer/manufacturer and got some good info on their testing methodology that gave me confidence they were doing the right thing. Mine was new, never mistreated so put it in my F-18 and its been working great.
dbsonic is online now  
Reply With Quote
Old 12-22-2016, 12:20 PM
  #27  
ija
 
Join Date: Nov 2007
Location: Oulu, FINLAND
Posts: 100
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by i3dm View Post
i agree its hard to tell, but these protocols usually are easy to reverse engineer, and if done right - work fine.
you see a variety of these boards for a reason, and mass wisdom is taking case - lots of people decoded these protocols with arduino and published their codes.

the chinese manufacturers just made the boards
I agree these protocols are not rocket science... BUT there are plenty of things you can fail. Practically all "copycat" chinese companies are just rushing to markets with "something" because they have no brand to protect! Those companies seem to be "ready to markets" once the very first prototype seems to work somehow; noone bother to test for example several decoders at same bus, bus conflicts, voltage brown outs and especially wide temperature range. Also component variation is often ignored. and so on...

Especially Futaba's SBUS2 is nasty; SBUS only stuff seems to work well when nothing else is connected. You connect sensor or two and it still works fine until the day when for example temperature sensor sends wrong magic value to the bus... KABOOM: hmmm, why I lost my control when temperature got 6degrees Celsius... and only when the sensor is set to certain slot. Damnit. Even Futaba has failed this with their SBUS only story as apparently they didn't plan SBUS2 when some of the SBUS only code was written; if you connect some genuine Futaba SBUS-only device to SBUS2 you see same. I have also been looking for some Arduino codes in past and there is / has been some with obvious hidden bugs! The challenge is that many Chinese companies just copy those codes without hesitation.

yep; I know both SBUS and SBUS2 protocols very well... Well enough in order not to buy any Chinese decoders nor telemetry sensors.
ija is offline  
Reply With Quote
Old 12-22-2016, 12:53 PM
  #28  
sirrom
My Feedback: (4)
 
Join Date: Dec 2001
Location: Sarasota, FL
Posts: 919
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Has anyone seen this product?

http://www3.towerhobbies.com/cgi-bin...eeIaApOU8P8HAQ

it looks as if you could use two of these to get the 15pwm channels all to sbus.

Patrick
sirrom is offline  
Reply With Quote
Old 12-22-2016, 02:54 PM
  #29  
DelGatoGrande
My Feedback: (23)
 
DelGatoGrande's Avatar
 
Join Date: Mar 2004
Location: ATHENS, , GREECE
Posts: 2,918
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by sirrom View Post
Has anyone seen this product?

http://www3.towerhobbies.com/cgi-bin...eeIaApOU8P8HAQ

it looks as if you could use two of these to get the 15pwm channels all to sbus.

Patrick
just spent 50$ more and get another receiver http://www3.towerhobbies.com/cgi-bin...&I=LXBWGP&P=ML
Two of this will give you 16 channels
DelGatoGrande is offline  
Reply With Quote
Old 12-22-2016, 09:23 PM
  #30  
ija
 
Join Date: Nov 2007
Location: Oulu, FINLAND
Posts: 100
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Makes much more sense to select Sbus capable servos than buy those overpriced Futaba decoders. That's the way to save in cabling also.

Ilkka
ija is offline  
Reply With Quote
Old 12-23-2016, 04:59 AM
  #31  
basimpsn
My Feedback: (5)
 
Join Date: Dec 2001
Location: Mia, FL
Posts: 2,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

It's a very cool device...I found it very useful last year when one of my quad aux output malfunction.

https://www.youtube.com/watch?v=k5beWVtTICs&t=23s
basimpsn is offline  
Reply With Quote
Old 12-23-2016, 11:30 AM
  #32  
i3dm
Thread Starter
My Feedback: (51)
 
Join Date: Jun 2004
Location: Reut,Israel
Posts: 4,117
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by basimpsn View Post
It's a very cool device...I found it very useful last year when one of my quad aux output malfunction.

https://www.youtube.com/watch?v=k5beWVtTICs&t=23s
how did it work for you?
i3dm is offline  
Reply With Quote
Old 12-23-2016, 12:24 PM
  #33  
basimpsn
My Feedback: (5)
 
Join Date: Dec 2001
Location: Mia, FL
Posts: 2,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Works like a charm save me from buying another TX with FHSS ppm protocol...at the time my 8fg only support FASST.
basimpsn is offline  
Reply With Quote
Old 12-27-2016, 06:39 AM
  #34  
i3dm
Thread Starter
My Feedback: (51)
 
Join Date: Jun 2004
Location: Reut,Israel
Posts: 4,117
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by basimpsn View Post
Works like a charm save me from buying another TX with FHSS ppm protocol...at the time my 8fg only support FASST.

Did you happen to use the SBUS decoder function?
i3dm is offline  
Reply With Quote
Old 04-27-2017, 07:18 AM
  #35  
JimDrew
My Feedback: (16)
 
Join Date: Oct 2005
Location: Lake Havasu City, AZ
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by stevekott View Post
We just officially released the X24 Channel Expander.

This gives you dual 100A battery inputs, 24 outputs - all with center and end point adjustments (like having 12 JR MatchBoxes), dual programmable BEC outputs, 5 sets of current sensing matching (so you can match servos together automatically by just selecting a master and up to 3 slaves), 16 individual 3 stage sequencers (for gear door sequencing, and whatever else you can dream up), 4 receiver inputs (supporting 8 different serial protocols), failsafe controls, low voltage warnings, full diagnostic display showing lost frames, voltage, current draw, servo positions, etc., boosted servo signal outputs, virtually simultaneous output of ALL servos gives the lowest latency of any expander available, and a LOT more! The X24 operates from 2.1 volts to 16 volts.

For more details see: http://www.xtremepowersystems.net/products.php?cat=8

Last edited by JimDrew; 04-27-2017 at 07:21 AM.
JimDrew is offline  
Reply With Quote
Old 04-27-2017, 10:20 AM
  #36  
mr_matt
My Feedback: (10)
 
mr_matt's Avatar
 
Join Date: Dec 2001
Location: Oak Park, CA,
Posts: 10,297
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Cool, does it have SBus output?
mr_matt is offline  
Reply With Quote
Old 04-27-2017, 10:38 AM
  #37  
JimDrew
My Feedback: (16)
 
Join Date: Oct 2005
Location: Lake Havasu City, AZ
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

No. If you need SBUS output, just use a Y-cable.

Just curious - why would you want SBUS output?
JimDrew is offline  
Reply With Quote
Old 04-27-2017, 10:48 AM
  #38  
mr_matt
My Feedback: (10)
 
mr_matt's Avatar
 
Join Date: Dec 2001
Location: Oak Park, CA,
Posts: 10,297
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by JimDrew View Post
No. If you need SBUS output, just use a Y-cable.
If you offer the same value as a Y cable that is probably the direction I would go.
​​​​​​​
I needs SBus output to go to my SBus servos.

I assumed if you could take in 4 SBus inputs from 4 separate receivers, that you are selecting the best signal from the 4 or somehow combining the 4 signals, who knows. So that is the SBus output I would want.
mr_matt is offline  
Reply With Quote
Old 04-27-2017, 11:42 AM
  #39  
JimDrew
My Feedback: (16)
 
Join Date: Oct 2005
Location: Lake Havasu City, AZ
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

OK, fair enough. I have never thought about that feature. It's easy enough to do, so I will look into it. However, the whole idea of the X24 is so that you properly power your servos. SBUS is limited to 5A max for all of the servos on the bus, and that is nowhere near enough current for even two servos.

Last edited by JimDrew; 04-27-2017 at 11:45 AM.
JimDrew is offline  
Reply With Quote
Old 04-27-2017, 01:54 PM
  #40  
FenderBean
 
FenderBean's Avatar
 
Join Date: Feb 2006
Location: Fort Hood Tx
Posts: 6,357
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Sbus with the Emcotec battery backer system solves all the Sbus problems. Its hard to get the stuff but for large jets or planes only way to run Sbus safely
FenderBean is offline  
Reply With Quote
Old 04-27-2017, 02:57 PM
  #41  
JimDrew
My Feedback: (16)
 
Join Date: Oct 2005
Location: Lake Havasu City, AZ
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

FenderBean, then perhaps you are not aware of what the problem actually is? The problem is not related to battery system, it is related to powering a string of servos from a single connection. Servos can pull a lot more current than most people realize. Servos also do not draw their highest current in a stalled condition. Servos typically draw anywhere from 2-5 times their stall current during a direction change, which is when the servo is moving one direction and told to move the other way. To get those super fast transient times, servos don't just stop the motor before reversing directions. Instead, they reverse the motor voltage against the moving gear train. The result is a massive current spike that greatly exceeds the stall current. For example - I have a 33% Hangar 9 Extra 260. It has 7 of the JR8711 servos on it - 2 on each wing, 1 on each elevator half, and 1 on the rudder. It's an electric powered plane, so it doesn't have any other servos (for throttle or choke). Sitting idle on the ground, the current draw is around 150mA. While flying I see anywhere from 1A to 8A doing normal pattern stuff. However, on a snap to snap maneuver, it pulls a little bit over 60A of peak current. It's not a long peak (a bit more than 25ms) and tapers off into the high single digits after another 1/4 of a second, but it certainly occurs. A servo connector is technically only good for 5A. With SBUS (or any other serial stream protocols) you are relying on a single wire (with a known 5A limitation) to power all of the servos on the bus. Because it's physically impossible to draw more current than a wire and connector will handle something has to give, and that is the voltage that is being carried on the wire, which results in a brown out. The level of brownout can be anything from significantly reduced holding force of the servo(s) to the rebooting of the receiver. By plugging each of your SBUS servos individually into a bus with huge power handling capabilities (like the X24 provides), you completely eliminate any potential brown out conditions.

The Emcotec system is a lower current version of what is built into the X24, so thanks for pointing that out - I had not seen their system. The X24 can handle 100A per battery input - which is really just a marketing hype thing. In reality, the servo pins will all burn off long before you reached the max capability of the system.

Last edited by JimDrew; 04-27-2017 at 03:02 PM.
JimDrew is offline  
Reply With Quote
Old 04-27-2017, 04:13 PM
  #42  
FenderBean
 
FenderBean's Avatar
 
Join Date: Feb 2006
Location: Fort Hood Tx
Posts: 6,357
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I'm aware, plenty of folks have posted about it that's why I suggested the emcotec since your not pushing everything through a single hub. Each servo has its own hub. It still gives each servo it's own connection with some crazy large wires that can handle more than anything put through it. Not saying there is anything wrong with your system at all.
plus with the emcotec you can use up to four large leads.

Last edited by FenderBean; 04-27-2017 at 04:16 PM.
FenderBean is offline  
Reply With Quote
Old 04-27-2017, 05:21 PM
  #43  
JimDrew
My Feedback: (16)
 
Join Date: Oct 2005
Location: Lake Havasu City, AZ
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Ah, I was looking at a different product with the same name:

DPSI Ampere - battery backer | DPSI Ampere | DPSI Systems


Do you mean this $435 product with even less current capability?:

Dreamworks Model Products LLC

Maybe we should raise the price of the X24!
JimDrew is offline  
Reply With Quote
Old 04-27-2017, 06:49 PM
  #44  
FenderBean
 
FenderBean's Avatar
 
Join Date: Feb 2006
Location: Fort Hood Tx
Posts: 6,357
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

im referring to the DPSI 2018, it was made by Robbie/Futaba orig but I guess they took over it. For people looking to run Sbus and worry about single small leads and terminals the 2018 is the best solution for large models. Thats all im saying in reference to the original posters ideas
FenderBean is offline  
Reply With Quote
Old 04-27-2017, 07:59 PM
  #45  
JimDrew
My Feedback: (16)
 
Join Date: Oct 2005
Location: Lake Havasu City, AZ
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Maybe it was the best solution, but not any longer. The X24 offers better current capability, the lowest latency, and a lot more features - and for less than 1/2 the cost.
JimDrew is offline  
Reply With Quote
Old 04-27-2017, 11:52 PM
  #46  
Springbok Flyer
 
Springbok Flyer's Avatar
 
Join Date: Jun 2006
Location: Gold Coast, Queensland, AUSTRALIA
Posts: 1,205
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default No substitute.....

I am using the Emcotec/Robbe/Futaba DPS2018 in two of my jets. It is most certainly better than the usual Sbus commonly in use. HOWEVER, I am also using the Powerbox PBUS (PowerBus) system on two of my latest jets - there is simply nothing to touch it. Do yourself a favour and check it out on the Powerbox website. In conjunction with the Powerbox Royal and with either the PWM or Sbus servo adapter hubs it does more than anything else and offer all the power drainage protection you need.

Cheers,

Jan
Springbok Flyer is offline  
Reply With Quote
Old 04-28-2017, 07:18 AM
  #47  
JimDrew
My Feedback: (16)
 
Join Date: Oct 2005
Location: Lake Havasu City, AZ
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I am well aware of the PowerBox systems. The X24 does more (with more power handling and without using regulators) than any system on the market. The very last thing you want is a system that regulates the input voltage to a lower voltage for the servos. If you see a fancy anodized heat sink on any power system, you should run! As a long time radio manufacturer, I can tell you that 99.9% of all problems we have encountered with our customers throughout the last 10+ years has been failures of the power system, with the vast majority of those issues being due to regulators, followed by switches, and then extensions. I created the X24 to solve this issue. I mainly fly jets, and that is what I designed the X24 around. The X24 provides more than enough current, and uses a programmable soft switch input to put the X24 into sleep mode (it's never actually "off", and will sit for years that way before draining the batteries completely). The BEC outputs can be used to power LED lighting independently (or ignition systems for gas engine powered aircraft). There are 16 individually programmable 3-stage sequencers which can be used for anything, but gear door sequencing is what I use them for - a single channel can do everything. The X24 has the lowest latency of any device in existence. ALL of the servo outputs are updated at the same time. There are not groups of 2 or 4 being output together, instead all 24 outputs are output together. This completely eliminates the .9ms to 2.2ms latency that occurs between "groups". If you have 12 channels (6 groups of 2), the last group of 2 servos occurs ~8ms after the 1st group. In a heli application, that would mean a swash plate that wobbles. In a jet application it could mean an induced roll. The X24 has numerous other features (like current matching of servos), many of which have come from the feedback of our customers and top pilots from all over the world. We can of course add new features at anytime and people can update their X24 themselves. I have been flying R/C for over 40 years, everything from foamies to turbine jets to 50% giant scale 3D. As a pilot I know what I need for features and simplicity of setup. As a radio manufacturer I know what failures occur in all of the various systems. As an engineer I know how to design a system without these failures. The X24 is the result.
JimDrew is offline  
Reply With Quote
Old 04-30-2017, 05:17 PM
  #48  
Viper1GJ
My Feedback: (19)
 
Viper1GJ's Avatar
 
Join Date: Oct 2003
Location: Saint George , SC
Posts: 1,057
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by JimDrew View Post
Maybe it was the best solution, but not any longer. The X24 offers better current capability, the lowest latency, and a lot more features - and for less than 1/2 the cost.
Jim,

I have learned a lot about using the Futaba R7008SB from this thread. I am thinking of using the X24 with two Futaba R7008SB receivers in my Avanti XXL. I want to use a Cortex gyro. How do you use the X24 with a Cortex gyro and still get full power to the servos?

Thanks
Gary
Viper1GJ is offline  
Reply With Quote
Old 05-01-2017, 07:30 AM
  #49  
JimDrew
My Feedback: (16)
 
Join Date: Oct 2005
Location: Lake Havasu City, AZ
Posts: 249
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Like most gyros, the Cortex controls the servos directly so there is no way to interface it to the X24. However, when I designed the X24 I built in a control expansion port. We are testing the X24 PRO model right now, which has a complete flight stabilization system built-in. This system has a 3 axis gyro, 3 axis accelerometer, 3 axis magnetometer, and altitude sensor. Besides the normal stability system, you will be able to do things like "axis-lock" where it locks an assignable axis (enabled via a switch on your transmitter). For example, you will be able to go down the deck with the horizontal lock enabled and do a 50 point roll by moving just the ailerons, and without changing course or losing altitude. The elevator/rudder surfaces are corrected by the flight stabilization system as necessary.

The X24 PRO model won't be available for a few months. All X24 versions can be upgraded to the PRO version.

Last edited by JimDrew; 05-01-2017 at 07:32 AM.
JimDrew is offline  
Reply With Quote
Old 05-01-2017, 02:32 PM
  #50  
stevekott
 
stevekott's Avatar
 
Join Date: Nov 2006
Location: yorba linda, CA
Posts: 593
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Jim,

I noticed that on the x24 there are 4 serial rx ports.

Does that mean that you could hook up 2 7008SB's and have true redundancy if one of them lost signal?
stevekott is offline  
Reply With Quote

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service