Connecting to a CNC machine, pros and cons of USB vs PP vs Ethernet etc.

[JAZZCNC]

If the communication system was explicitly designed for control purposes, you can! If you want to see a video example, the spindle encoder in the earlier rigid tapping video Dean posted is connected over CANbus. I'm sure that you can also do it over other things like Modbus/RS485 too...but I'm not going to bother finding examples.

There you go splitting hairs again when you actually don't know the full story or have experience of the controller.!!
The only reason it's using CANbus because it's a External I/O module that connects to the Main Controller Via CANbus. Hood could have easily connected straight to the main IP-A controller, but with So much I/O to make the Chiron work he's using the I/O Module.!!. . . The Controller still does all the Work and number crunching. CANbus is just used has an easy and stable way to move I/O modules around large machines to localise I/O and keep short Signal wire runs. Other wise it would mean running long signal wires back thru machines risking EMF issues.

Yeah, I saw the jester, but I'm afraid that it didn't entirely put my mind at ease at the time. I guess I'm jaded, heard too many 'jokes' where someone's actually a bit more serious than they're letting on etc., If I actually knew you, of course, I'm sure my interpretation would have been totally different!

Rest assured your not and never where in any Danger from me ***REMOVED***. And if you was I'm not stupid enough to post my intentions on a Forum. ***REMOVED***

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[Jess]

There you go splitting hairs again when you actually don't know the full story or have experience of the controller.!!

magicniner claimed that no remote communication system can do rigid tapping. CANbus is a remote communication system, and as hood demonstrates, CANbus can do rigid tapping.

I don't see what the problem is?

[JAZZCNC]

magicniner claimed that no remote communication system can do rigid tapping. CANbus is a remote communication system, and as hood demonstrates, CANbus can do rigid tapping.

I don't see what the problem is?

Problem is CANbus isn't doing the ridgid tapping the Controller is doing it. CANbus is just shifting data which it does best.!!

I think the Valid point Magicininer was making is that it's not the Communication protocol that does the work on any machine usually it's the main Controller it's self.! . Just Like it's the Encoder module working in conjunction with the Main controller on the Cslabs devise. CANbus just lets them talk to each other, albeit very fast.
Also in this case it's actually the main controller that is doing the coordinated movement between spindle and Axis by controling the Servos (Hood's spindle is Servo driven) which is connected to Control software via Ethernet.
The Encoder module is just reading the High resolution encoders which require high data rates which CANbus is very good at.! The controller deals with these internally and send the relavent signals needed for movement to what ever does the moving or turning.!!

[m_c]

Would you pair put the handbags down! :)

In terms of Mach3, Ethernet is the more reliable communication method for external motion controllers.
The reason for this, is Mach3 can't handle any errors or glitches in the communication method.
Ethernet handles errors and glitches at a hardware level, it's also an isolated system, so is much more tolerant of external noise, and should a packet fail to reach it's destination, the hardware (ok, it's technically the embedded code in the Ethernet controller if you want to split hairs) will handle the problem and resend it until it reaches it's destination.
USB doesn't have that, so any packet of data that gets corrupted, has to be detected and handled by software. I'm sure if the plugins could be designed to do this, they would, however it's one of the things that Mach3 was never designed to handle, as it was originally written to talk directly to the parallel port.
I think it would be fair to say external motion control, was simply patched onto the Mach3 core.

One key point to remember, is once you involve Ethernet or USB, you are no longer running realtime. All you're essentially doing is running a faster version of ye olde RS232, in that you send commands to a controller, and the controller (hopefully) tells you it's been done.


However, USB can be used reliably. I run several KFlops, and they are far more stable than my USS ever was with Mach3. My lathe still occasionally locks up Mach3 (my manual lathe is the sole trigger for this!), but no where near as often as the USS ever did.
I am in the process of moving to KMotionCNC, as it can handle communication problems far more gracefully (and it has less issues, but that's for another topic!), and will happily resume once things are back to normal.

[JAZZCNC]

Would you pair put the handbags down! :)

However, USB can be used reliably. I run several KFlops, and they are far more stable than my USS ever was with Mach3.

No my Hand bag is always read for Action.!!. . Lol

Now Come on M_C we both know you are talking about a very High quality product when using Granite's Kflop controller it's not your average USB Mach3 controller.
The point I was making in first place is that USB isn't stable as Ethernet when used with Mach3 which we know thru experience is true. We Have Both pulled our hair out with USS(USB Smooth Stepper for those we are wondering.!!) and I've done much the same with every other run of the Mill USB controller for Mach3.
Ethernet on the Other hand is another ball Game. Classic example is the Pokeys 56/7E and now 57ECNC which do Motion control they are cheap and work great they never Miss a beat. The 56U on the other hand was a pain when used for motion control with Mach3, mainly I think because it relied on USB for 5v but still it couldn't be trusted.!

USB driven card Isn't ok for Motion control unless your prepared to spend on quality devices like Granite's Kflop etc so to me it's not for the average DIY user and best avoided.! And now with Ethernet devices coming more available at sensible money what the point.!

[m_c]

magicniner claimed that no remote communication system can do rigid tapping. CANbus is a remote communication system, and as hood demonstrates, CANbus can do rigid tapping.

I don't see what the problem is?

In the original context of this thread, which was to do with computer to machine controller interfaces, magicniner's claim is correct.
In the case of CS-Labs they use it for inter-module communication, which is where it excels.

CANbus is a very resilient system, and can be very fast, however nobody uses it as a communication method between a computer and CNC machine. You could use it for realtime operation if you designed a suitable internal slot card that the computer could access directly and control in realtime, but you're then into a very glorified parallel port like system.

[Jess]

however nobody uses it as a communication method between a computer and CNC machine

Not on Mach 3; but that part of the conversation hasn't been about Mach 3 for several days now! And, of course, that ethernet motion controller is a computer, but that's not what any of us mean.

On the LinuxCNC side, whilst RS485 is more popular, there's definitely people interfacing their machines to their computers with CANbus.

The hardware's been available for years. There's plug in cards that provide the interfaces plus industrial PC motherboards that already have CANbus and/or RS485 on board.

but you're then into a very glorified parallel port like system.

Rather unfair and misleading. CANbus gives you something much closer to a PCI I/O board in function - you're not having to do software step generation, and you actually have the ability to read encoders.

To seque this into the topic of the thread:

Approaches that allow your computer to more directly control the machine is definitely of huge value if you've got some complicated/non-standard kinematics going on, but even on a standard perpendicular axis mill then there's a potentially a significant financial saving to be made.

The additional costs associated with Mach 3; Windows licenses, Mach 3 licenses and ethernet hardware motion controllers could buy you all the electronics you need to convert something like a Novamill or Triac, even once you've thrown in something like a Mesa Anything I/O.

LinuxCNC on BeagleBone Black? A back of the envelope calculation suggests that I can have my entire dedicated control computer as well as software and breakout for the cost of the Mach 3 license alone; that's a lot of difference.

[m_c]

I wouldn't normally take the bait, especially from someone who has very little if any practical experience building or running CNC machines, but here goes.

And, of course, that ethernet motion controller is a computer.

No it's not. It'll be an embedded micro-controller, DSP or FPGA, which nobody who deals with such things will class as a computer.

On the LinuxCNC side, whilst RS485 is more popular, there's definitely people interfacing their machines to their computers with CANbus.

The hardware's been available for years. There's plug in cards that provide the interfaces plus industrial PC motherboards that already have CANbus and/or RS485 on board.

But not in the form of communication between a computer and a motion controller. In LinuxCNC the computer is the motion controller. External motion control cards are not available for LinuxCNC, as they defeat the whole purpose of LinuxCNC's realtime kernel.
CANbus/RS485 is just another method of communicating between the controller and drives/IO boards, just like lots of other possible options.

Rather unfair and misleading. CANbus gives you something much closer to a PCI I/O board in function - you're not having to do software step generation, and you actually have the ability to read encoders.

And what exactly is a parallel port?
Last I checked, it was simply a bunch of I/O pins conveniently arranged in a standard format, that can be accessed directly by software (I know windows blurs this, but the principle is still there), just like a PCI IO card does.
If you really wanted, you could make a parallel to CANbus to BOB setup, and it would give you a similar setup to using a direct CANbus PCI card, just with more limited IO and speed.

To seque this into the topic of the thread:

Approaches that allow your computer to more directly control the machine is definitely of huge value if you've got some complicated/non-standard kinematics going on, but even on a standard perpendicular axis mill then there's a potentially a significant financial saving to be made.

The additional costs associated with Mach 3; Windows licenses, Mach 3 licenses and ethernet hardware motion controllers could buy you all the electronics you need to convert something like a Novamill or Triac, even once you've thrown in something like a Mesa Anything I/O.

LinuxCNC on BeagleBone Black? A back of the envelope calculation suggests that I can have my entire dedicated control computer as well as software and breakout for the cost of the Mach 3 license alone; that's a lot of difference.

And this argument over cost will rumble on indefinitely.
The fact remains for your typical DIY CNC enthusiast, the familiarity of windows based computer systems, means they'll remain the most popular option for the foreseeable future, despite the additional cost.
You've got to remember, a lot of people who build CNC machines, are not computer or electronic geeks.

For me personally, time is money, so although I may save on licenses, the extra time familiarising myself with a new operating system/hardware, is time that could be spent making money. For me running Dynomotion products, a KFlop costs about £230 delivered. For that I get nearly everything needed for a motion controller including some very reliable software, and only need to add a windows PC, which can be picked up for very little. I can have the controller configured and ready to go in a couple hours. If the computer fails (which lets be honest, is usually the weakest link), I swap the configuration files onto a new computer, and away I go again.

Add something like Mesa cards into the mix, and you've then got to start swapping parts around, and hope they didn't get killed when the computer died.

[JAZZCNC]

Both Ethernet and usb are digital so noise is likely to effect both if large enough, i have my uc300 running an inch away from my 2200w vfd and two inches from a honking great 55v toroidal transformer without issue so sounds like your noise may have been in your power supply, were you using ac filters? either that or there was something massively wrong happening in the next room.

No offense meant to you Jon but I'm doing this all the time and know all about what or not to do. The particular "next room" incident was actually a Compressor with faulty starter but the more the problem was the USB Smooth stepper had a design flaw so didn't take much to upset it. (It was one of the very first models.!! I've since tried newer versions but still had problems.!)

Regards the uc300 then fire up a Tig or Plasma cutter up near by and see how it reacts.! Vfd's and torodial supplys are nothing and it would be very bad state if they couldn't live along side one or both.
It's the things that go off around the machine that seem to affect USB/PC but what exactly I'm yet to determine and believe me I've looked and tried to put my finger on what causes it.!

End of the day I'm into building and using a CNC machine and haven't got time to chase the many things that can bring it down. What I can do is eliminate using those that don't meet the mark by testing them as I go along building machines.
First test is the Tig/Plasma test and then I work backwards from there.!!. . Very few USB devices Pass this test.!

LinuxCNC on BeagleBone Black? A back of the envelope calculation suggests that I can have my entire dedicated control computer as well as software and breakout for the cost of the Mach 3 license alone; that's a lot of difference.

Ah ah now we get to the meet of the Beef.!! . . . Linux Geek. . . Wanting to Pick a fight with Mach user's.!! . . . . Well Not happening I'm afraid been there too many times.! . . . Jog on.!

[Boyan Silyavski]

That thread made me laugh, really. How did i miss it. There is no respect for experience it seems. "Knowledge|" without experience is just a collection of facts or suggestions, from here and there.


I don't know what the hassle is about? Most expensive motion controllers have tried USB and then upgraded to Ethernet controllers. See Galil for example. Even cheap controllers have done the same. So there must be a reason for that.


What happens at low level / cheap/ controllers is that they do the same just like a follow up , after a couple of years, when parts are already cheaply available for the low end market.


Or you say people who make industrial control are stupid and don't know their business.


My blue Makita drill worth 360euro drills holes in steel and my friends green Bosch worth 50 euros drill holes in steel. My Makita can drill 10 years everyday without a glitch and the Bosch will die in month of industrial environment.


As i have pure HF plasma at home let me clear something. Glitches come from not good home grounding, the non shielded mouse and other Pc cables, not from USB or Ethernet cable if they are shielded and all electronics are in a shielded box. So basically both should work if everything to the last detail is well done.


Well Jess, now we know you . You have well presented yourself here. I am half expecting soon to hear that RP is better than ball screw and that HD alu profile gantry is stronger than steel one..