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  1. #61
    Quote Originally Posted by Jon. View Post
    Really id say its down to personal preference. I think if your using an Ethernet controller over usb because of noise its because you haven't taken the correct steps to shield the controller and that you are also happy to have your controller bombarded with noise, just because it can it doesn't mean it should. You may be correct in that ethernet has better protection against noise but that is providing the noise is entering via its ports. If your talking about noise that is infact capable of entering a grounded enclosure then there's no telling how that noise is going to enter the board, but you say it does fair better but with the correct steps either can work so again personal preference.
    My thoughts are the same, +1 for this post.

    If people stoped for a second and actually read what was being said, then...never mind... I guess we are all limited in some ways to our own experiences, a level of understanding for things and struggle with other things.

    .Me
    .Me

  2. #62
    Quote Originally Posted by Jon. View Post
    Really id say its down to personal preference. I think if your using an Ethernet controller over usb because of noise its because you haven't taken the correct steps to shield the controller and that you are also happy to have your controller bombarded with noise, just because it can it doesn't mean it should. You may be correct in that ethernet has better protection against noise but that is providing the noise is entering via its ports. If your talking about noise that is infact capable of entering a grounded enclosure then there's no telling how that noise is going to enter the board, but you say it does fair better but with the correct steps either can work so again personal preference.

    Bearing in mind a pc usually has multiple usb ports, but can only handle a single ethernet port so its restrained in that respect.
    This is the situation Jon from my point of view has someone who Builds machines for others compared to someone like your self who just uses a Machine in a DIY capacity or maybe even Small business venture.
    Last Machine I Built went to Scotland which is a 500mile 10hr round trip. I can't afford for to be running up and down the country chasing ghost problems.

    It's a FACT whether you agree or not that USB gives more trouble than Ethernet. Just becuase it's working for you without issue doesn't mean it will or does for others. I know this to be true thru experience dealing with Chasing USB ghost's.
    I pride my self on the Quality of my Control box's in comparison to many other builders, (and believe me I've been inside a fair few so called Top rated machines costing Several 1000 more than what I build that I wouldn't even turn on.!!) I use correct filtering and ground techniques inside Industrial Steel cabinets along with shielded cables using differential signaling. So I know it's nothing to do with My end but still USB throws Ghost problems and Lockups that cannot easily be explained.

    This I can't and Don't want happening on any machine I put my Name on. This is the reason why EVERY component I use when building a Machine gets tested on my own personal machine and for several Months at a time not just a few hours. Could say I torcher them to death or Glory.! . . . NO USB device as passed the Tig/Plasma test.!! . . . . Yes there well maybe some of the Higher end devices that will pass but why should I bother when I've found Ethernet is consistantly more stable on just about every device that uses it. The Cslabs Controllers I use these days are Bullet proof and Never fail or throw wobblys for unexplained reasons.

    AND just to prove that USB freaks out when Ethernet doesn't Purelogics PLCM-E3 and Pokey's 57CNC both come with USB and Ethernet connections. The USB on the PLCM couldn't even handle the Mig test before crazyness happened. Ethernet it didn't flinch and when Tig was used it didn't seem to affect it either unless I went right up next to the Controller.!! . . . Pokey's I'm still torchering.!!

  3. #63
    I suspect that the underlying UDP ethernet protocol is nearly as error prone as the USB protocol, however, the TCP/IP layer which sits above it and does the error correction is (as has been pointed out) extremely robust so the end result is much better.

    I can see both sides of the argument but theory is worth nothing if it doesn't work in practise...

    For what it's worth, I've got a 3D printer which is extremely noise sensitive on the USB connection (to the point I now download the print to a memory card and print from that) and a USB CNC controller which I haven't had a problem with but there are dire warnings on the website about using a good quality cable - see https://www.youtube.com/watch?v=NUu9xwDfJ9k

  4. #64
    Jon.'s Avatar
    Location unknown. Jon. Last Activity: Has a total post count of n/a. Referred 6248 members to the community.
    I good example of usb technology would be an external hard drive ... and in my experience these never loose connection. So what is being compared here is not the technology but the boards themselves as proven everywhere, usb is extremely stable... o hang on my ethernet card needs resetting. damn thing screws up all the time. :P
    Last edited by Jon.; 08-06-2015 at 09:23 PM.

  5. #65
    Quote Originally Posted by FatFreddie View Post
    I suspect that the underlying UDP ethernet protocol is nearly as error prone as the USB protocol, however, the TCP/IP layer which sits above it and does the error correction is (as has been pointed out) extremely robust so the end result is much better.

    I can see both sides of the argument but theory is worth nothing if it doesn't work in practise...

    For what it's worth, I've got a 3D printer which is extremely noise sensitive on the USB connection (to the point I now download the print to a memory card and print from that) and a USB CNC controller which I haven't had a problem with but there are dire warnings on the website about using a good quality cable - see https://www.youtube.com/watch?v=NUu9xwDfJ9k
    Looking at a USB cable, it appears to use ground, power, and data in and data out. So, single-ended connections. Typical Ethernet connections use twisted-pair and, presumably, differential signalling. That suggests that Ethernet, at a hardware level, should be intrinsically more noise-resistant (although my own 3D printer has run for many, many hours over USB without any problem, although that is in a domestic environment without machine tools and EMI generators nearby). I think FatFreddie has it right with reference to TCP, though. A typical USB connection will be using an application-specific protocol that assumes a reliable connection (I know my 3D printer does this as I've looked at the code) so any data corruption or loss will be catastrophic, where the TCP protocol gives a highly reliable connection; any packet loss or corruption short of losing the whole connection will be detected and corrected by resending packets. Ethernet-connected motion controllers appear to use IP as they need network addresses and I presume they also use TCP over this - why shouldn't they? So, an error-correcting protocol over a more noise-resistant hardware connection gives so much more safety margin than a simple protocol over less-protected hardware. Be interesting to see the Ethernet-level error counts in a noisy environment, though.
    What you are losing, of course, is any claim to a real-time protocol, but as the network connection is being used to transfer, typically, high-level movement instructions which can be easily buffered, by buffering a couple of seconds'worth of data you can still withstand a short loss of communication during a noise burst, the TCP stuff does its job and makes sure the data gets there eventually, and the pulse generator bit of the motion controller chunters away happily working from buffered data.
    Conclusion - theorist meets practical experience, shakes hands, and goes off for a pint...
    Personally, I like learning from experience, and preferably someone else's experience 'cos that costs me less! But trying to relate that back to theory might give a bit more insight sometimes and lead to a better understanding and maybe a way to move forward. Cathedral builders used experience to create magnificent buildings but theory and better understanding of materials gives us skyscrapers. If that is an advance...

  6. #66
    Quote Originally Posted by Neale View Post
    Looking at a USB cable, it appears to use ground, power, and data in and data out. So, single-ended connections. Typical Ethernet connections use twisted-pair and, presumably, differential signalling. That suggests that Ethernet, at a hardware level, should be intrinsically more noise-resistant (although my own 3D printer has run for many, many hours over USB without any problem, although that is in a domestic environment without machine tools and EMI generators nearby). I think FatFreddie has it right with reference to TCP, though. A typical USB connection will be using an application-specific protocol that assumes a reliable connection (I know my 3D printer does this as I've looked at the code) so any data corruption or loss will be catastrophic, where the TCP protocol gives a highly reliable connection; any packet loss or corruption short of losing the whole connection will be detected and corrected by resending packets. Ethernet-connected motion controllers appear to use IP as they need network addresses and I presume they also use TCP over this - why shouldn't they? So, an error-correcting protocol over a more noise-resistant hardware connection gives so much more safety margin than a simple protocol over less-protected hardware. Be interesting to see the Ethernet-level error counts in a noisy environment, though.
    What you are losing, of course, is any claim to a real-time protocol, but as the network connection is being used to transfer, typically, high-level movement instructions which can be easily buffered, by buffering a couple of seconds'worth of data you can still withstand a short loss of communication during a noise burst, the TCP stuff does its job and makes sure the data gets there eventually, and the pulse generator bit of the motion controller chunters away happily working from buffered data.
    Conclusion - theorist meets practical experience, shakes hands, and goes off for a pint...
    Personally, I like learning from experience, and preferably someone else's experience 'cos that costs me less! But trying to relate that back to theory might give a bit more insight sometimes and lead to a better understanding and maybe a way to move forward. Cathedral builders used experience to create magnificent buildings but theory and better understanding of materials gives us skyscrapers. If that is an advance...
    Really well said Neale.
    .Me

  7. #67
    There is also the cable length issue with USB (just saying) ..Clive

  8. #68
    Quote Originally Posted by Neale View Post
    Cathedral builders used experience to create magnificent buildings but theory and better understanding of materials gives us skyscrapers. If that is an advance...
    Yes very well said but just one small detail.? . . . Those Skyscrapers where built by Master builders with years of experience.! Those builders would not use inferior products and therefore make sure those products where well tested by people experienced in testing material Theory.!!

    Theory and Experience work together for advancement but experience "TESTING" ultimately Wins and as the final say on what works and what doesn't.!!!
    Last edited by JAZZCNC; 09-06-2015 at 04:47 PM.

  9. #69
    Quote Originally Posted by JAZZCNC View Post
    Theory and Experience work together for advancement but experience ultimately Wins and as the final say on what works and what doesn't.!!!
    I'm not sure that I agree with that (I think that testing has the ultimate say) but that statement is only based on my experience and there's no theory to back it up...

  10. #70
    Would it be too presumptious that on a forum called mycncuk (which has a "mylittlepony" vibe to the name!), that most are hobbyists? In other words, not everyone wants to go to the far end of a fart over 'ethernet vs USB' (which would need a forum called IusemyCNCmachinetomillindustrialhardenedsteel.co.u k - which granted isn't as catchy)

    I'm a dabbler (I use my CNC to make pcbs) & I was pleased to see the back of Mach3 ...putting on those retro stick-on Bradley Wiggen-esque sidebruns & a pair of massive Lionel Blairs just to do a CNC session was a bit much. It was therefore like a breath of fresh air to migrate to cnc-usb, which uses erhm USB ....& I've not had one bit of bother with it. For the sake of balance, that's not to say others haven't has problems, which prompted the owner of cnc-usb to illustrate what a difference the actual usb cable can make...

    Last edited by HankMcSpank; 09-06-2015 at 04:17 PM.

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