On Saturday 06 June 2015 08:46:12 Alexander Rössler wrote: > Rafael writes: > > On 06/05/2015 01:18 AM, Alexander Rössler wrote: > >> Rafael writes: > >>> On 06/04/2015 07:13 AM, Ron Bean wrote: > >>>>> If you need one computer to see the GUI and one for realtime > >>>>> effects, why not just start out with a real computer and load > >>>>> Linux and LinuxCNC on it?
While there may eventually be a good reason for this old coot to switch, it hasn't arrived yet. > > .... snip > > > >>> In my HW support experience I came across PDP-11 systems running > >>> in steel mills, nuclear and hydro power plants, factories, etc. > >>> with little or no graphics. Most used VT100, some used more > >>> advanced color terminals. Systems with 32kW(ord) or 64kW RAM > >>> controlled huge machinery with RTOS on much slower CPU than we > >>> have today. > >> > >> The future are distributed systems. Distributed setups are > >> industrial standard and are used everywhere from automotive to > >> automation industry. CAN and Ethernet are used these days to > >> distribute > > > > neither one is suitable for strict real time. > > CAN as event triggered bus is not. You may understand TCP/IP as > Ethernet. However, Ethernet can be used as time-triggered bus too. > There are many standards such as EtherCAT and Powerlink which are > widely used in automation industry. Where are the drivers for this protocol? > >> functionality across different ECUs. The BBB is fine when it comes > >> to CAN but an even stronger platform from TI is coming up: the > >> BeagleBoard X15 with Gigabit Ethernet support > > > > Don't mix computer BUS and cabling. Two different things. Some > > cables do act as traditional extend bus but none at the length of an > > airplane or HMMVE. > > > > What good is Gigabit Ethernet when you need to connect a keypad, a > > switch, accelerometer, or optical sensor to BBB? Ethernet is not a > > bus, it's one of communications peripherals. > > You are wrong, Ethernet is a bus. When you take a look at the history > you will see that it started out with a very different physical > interface as nowadays. The huge advantage of Ethernet is that network > hardware is cheap (not all is RT compatible though) because it acts > only on the data-link layer (Ethernet frames). What I am talking about > are Ethernet hubs. > > The idea of time-triggered buses is to resend that every > cycle. Therefore, a higher network bandwidth means that one can use a > smaller cycle time. The bandwidth is not wasted as some people stated. > > Why not attaching the sensors you mentioned directly to the BBB? Just > create (or use one of the many) capes with a decent connector and you > are fine. > > If you want to go the industrial standard way you can buy sensors with > bus interface (I am not talking about I2C, SPI, ...). Onewire is > common for simple sensors. Another example in the automotive industry > it is pretty common to have ECUs that do only simple tasks like > reading out sensors and providing the data on a CAN bus. With > microprocessors getting cheaper and cheaper the industry will further > move into distributed systems. > Bus accessible devices usually come with a very proprietary interface, demanding that you buy the whole system from one vendor, usually at 400% price penalty. That likely will not fly here on this list. > >> On the other edge of the spectrum we have another low cost solution > >> that is currently funded on kickstarter C.H.I.P. a 9$ dollar Linux > >> computer with Bluetooth and WLAN => a cheap solution to connect > >> sensors. > > > > This is one of a kind toys that don't make a standard! Nor would > > anybody serious use it for a CNC machine. > > > >> I even heard about things like fly-by-wireless. Which boils down to > >> removing the wired buses inside a plane. So face the facts: Big > >> monolithic computer setups will soon be banned to server farms. > > > > Most airplanes and modern military vehicles use computers based on > > decades of developments on VME bus and it's derivatives because they > > need a lot of connections. That likely includes CompactPCI, it's > > emerging CompactPCI Serial, and VPX. > > > > As tiny lasers are getting cheaper, cost of building optical bus and > > compatible peripherals will become more common in the near future so > > we'll see even more data buses. > > Optical cables have different problems than metal cables. They have > more problems when it comes to mechanical stress. I am not sure they > will succeed copper wires that quickly. > > When you take a look inside an airplane you will see that the wiring > is consuming a lot of space inside the hull. The idea of replacing > some buses with wireless interfaces drastically reduces development > costs. So maybe in 30-50 years we will have wireless operating planes. Our (US) aging B-52 fleet was upgraded about a decade back from individual wires to just a couple heavy power cables and a few bits of coax, to run everything on those geriatric monsters over a network. Which bus protocol wasn't mentioned at the time, probably for security reasons, but they were sure pleased as punch that the upgrade lightened that airplane by 50,000 lbs. Originally designed for a 10,000 hour flight time, we do not have one left in the fleet with under 250,000 hours on the airplane today, and very little of its original airframe still exists. I expect that weight saveings made a diff in terms of crack discoveries during maintenance. > > Every computer in existence has a bus, available or not, for > > connections to additional peripherals. There is a bus on BBB, > > RaspberryPi, Radxa, and other little SBCs to add peripherals. My > > comment was about the problem with every little SBC having different > > connectors and their positions on the board while all are using > > "sandwich mechanical architecture" that cannot be expanded easily. > > What you are pointing out is that these devices do not come with > standard connectors. There are some capes (additional board that can > be put on the pin headers) that provide different connectors for > different applications. The BeagleBone Green will come with connectors > for the Groove sensors if you want something out of the box. > Furthermore, you have USB and Ethernet connectors available. > > However, I agree that connectors are a big problem in general when it > comes to computers. Only few capes address this problem an come with > pin headers to connect sensors/motors. However, that is one problem we > tried to address with the SandyBox and the different controller boxes > (Lin-Ctrl stepper driver, Print-Ctrl for the 3D printer) . They come > with standard Molex connectors to connect sensors, switches an motors. > > We are planning a future version of the SandyBox to address this > problem. So if you have ideas please share them. Fibre optics you said aren't mechanically solid enough. I would submit you chose the wrong cable/vendor. The proper fibre can be run down a cable chain with a 1 inch turn radius for the next 100 years if the jacketing is suitably immune to the coolant and lubes we use. I doubt you could say the same for the accompanying power cables to run the servo amps on the sides or rear caps of the motors. Its a guaranteed failure inside of a year if that power cabling has the 'Hot RED" die in its jacketing. I have no clue why, but that dye turns copper into copper oxide dust often in less than a year, and 100% in < 5 years. > > Based on what I've seen at Embedded computers trade show this year I > > can easily say that "computer data bus" won't go away any time soon. > > PCIe, VME, VPX, CompactPCI, PC104 and on and on. Companies are > > clearly commiting to support for advanced buses for the next 20 > > years or more. > > The application for PCIe and co is clearly high performance > computing. This is whole different application than what embedded > systems try to solve. Btw. there is Raspberry Pi model with a > PCB-style connector available. > > >>>> and a PCI slot for a GPU. Another solution might be something > >>>> like a BBB that plugs into a PCI slot in a generic PC. Either one > >>>> eliminates the USB connection, which is the real problem. Which would somewhat resemble the old IBM ARTIC card, which resided in an industrial grade PC, but once booted the pc was just the interconnection bus. > >>> Good idea assuming there would be a volume to keep the costs down. What sort of volume numbers are we discussing? I can easily see, over time as these people upgrade their cash cow's, something in the low hundreds. > >>> IMO it would be better if ARM architecture based universal bus > >>> would emerge for use in small embedded systems under $100 so that > >>> vendors would be encouraged to build controllers with "Mesa card" > >>> like functionality and other interfaces to handle digital and > >>> analog IO connections. This seems to be the way we are heading ATM. I also would add my voice to the chorus you've already read here, about the requirements to set up an account and login before we can see anything but the front page. Get rid of that forthwith, and let the sales numbers speak for themselves. And don't offer us any "blue sky" without labeling it as such, propaganda is fine, we'ed like very much to see what you might offer if there is interest, but label it as such with a button to click to vote for producting that product. And our vote will count when we have paypal'd the sheckles, putting our money when our mouth is. Aftermarket support for you product is something else you will need to do ala what PCW does now, which I believe is both excellent and a huge breath of fresh air (Many Thanks, Peter) in a business genre that is loaded with entirely too much proprietary stuff where a blown 75 cent transistor is a $300 trip to the vendor for that repair plus the machine is sitting idle for 10 days or so. There are on this list, a higher than average percentage of folks who can uncover it, find and and replace that bad transistor, possibly with an even better, faster, higher voltage one, cover it up and have that machine back in production in the time it would take to pack it and ship it. And we, I think, would gladly pay an extra 25% for the product if it ships either with a printed schematic and board layout, or ships with a password key that allows a known user to download what it takes to effect that repair from your web site for as long as the network exists. I know of at least one here with a Doctorate in EE. And while the best I can hang on the end of my name is ", C.E.T.", I can generally hold my own talking about ferrite curie temps, SOA's and dv/dt things until such time as my time is up, and I am 80 now. I think that makes me the senior member of these lists, and if I ever find a sweatshirt that says "Yes, I am a Senior Citizen, now gimme the damned discount", its mine, 2 or 3 copies even. ;-) > >>> This thread brought up interesting ideas and comments; good > >>> starting point for a "kickstart" project ;-) That too might be workable, if priced at 200% of what you estmate it might cost per unit of the first 25 used as the underwriting entry fee. Finish it up and start shipping when you have garnered the first 25 votes. When the qty's shipped says you have made up your NRE's on it, then adjust the price. In the meantime, let us see what this "Sandy Box" can do right now, and how much these initial units will cost, and let us decide if its worth our sheckles as I am in the market for something to run my new GO704 that I crippled myself up getting it set and leveled where it will run in my garage last Sunday. The "make an account and login to see anything" is a non-starter for me, and I expect for 90% of those subbed to these lists, as quite a few have mentioned that. We are first and foremost Linux people, and we do not click on every link just because its there. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
