Software control
04 Feb 2017 17:50 - 04 Feb 2017 17:52 #87304
by BP
Software control was created by BP
I plan on building the, Openbuild OX machine, with LinuxCNC Wheezy, and was looking for some insight on control hardware!
The choice I was looking at is Arduino with GRBL shield. Would this be a good option or is something better and easier to work with?
I have a good handle on the Machining aspect of milling having been a machinist for some time, but the electronics is a bit confusing!
I could go with USB or Parallel port.
Thanks in advance,
Brian
The choice I was looking at is Arduino with GRBL shield. Would this be a good option or is something better and easier to work with?
I have a good handle on the Machining aspect of milling having been a machinist for some time, but the electronics is a bit confusing!
I could go with USB or Parallel port.
Thanks in advance,
Brian
Last edit: 04 Feb 2017 17:52 by BP.
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04 Feb 2017 18:41 #87307
by tommylight
Replied by tommylight on topic Software control
Linuxcnc does not work with tthrough usb.
You can use parallel port or add on cards, they do work perfectly, but for parallel port it is a bit ricky to find one that has decent latency. They can all work properly, it might just limit the maximum steps you can send inside a second. In your case, most of them wil do just fine.
Arduino is nice for experimenting, and it does work somehow, it is very limitet.
You can use parallel port or add on cards, they do work perfectly, but for parallel port it is a bit ricky to find one that has decent latency. They can all work properly, it might just limit the maximum steps you can send inside a second. In your case, most of them wil do just fine.
Arduino is nice for experimenting, and it does work somehow, it is very limitet.
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04 Feb 2017 19:01 #87309
by BP
Replied by BP on topic Software control
Thanks Tommylight I wasn't aware of the usb problem and linux! Could you suggest something else to control the machine?
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04 Feb 2017 19:35 #87310
by tommylight
Replied by tommylight on topic Software control
Not realy, i use Linuxcnc for everything i possibly can. I have read a lot about arduino and BBB but they are to limited for my taste. I like to be able to use things as i like, not as someone else intended.
Also the price of BBB and other parts for acualy running it goes way beyond what i pay for a decent computer and monitor. I have owned computer shops so now i have friends who own computer shops that i helped start their businesses, so i can get a core2duo for 25 to 40 euro in perfect condition.
Also the price of BBB and other parts for acualy running it goes way beyond what i pay for a decent computer and monitor. I have owned computer shops so now i have friends who own computer shops that i helped start their businesses, so i can get a core2duo for 25 to 40 euro in perfect condition.
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04 Feb 2017 22:29 #87316
by Sparky961
Just to be clear, the problem with USB has nothing to do with linux. You can't reliably use USB for the type of motion control discussed here with Windows either.
USB is a nasty interface that has unfortunately become the defacto standard for plugging peripherals into a computer. This makes people think that it is the way to do it. However, most of the devices that are plugged in do not require very tight timing control, reliability, and super-low latency so it isn't an issue. Of course, Windows has it's own latency issues but that wasn't your question.
You need a real-time communication link and a real time operating system. Probably a simplification/generalization, but that's the basic idea.
Yes, there are USB motion controllers out there, but from what I understand the timing-critical stuff isn't happening over USB.
Someone do correct me if I'm wrong, but I've actually tried to write my own motion controller that uses USB and wasn't able to get beyond a certain point because of these limitations.
Replied by Sparky961 on topic Software control
Thanks Tommylight I wasn't aware of the usb problem and linux! Could you suggest something else to control the machine?
Just to be clear, the problem with USB has nothing to do with linux. You can't reliably use USB for the type of motion control discussed here with Windows either.
USB is a nasty interface that has unfortunately become the defacto standard for plugging peripherals into a computer. This makes people think that it is the way to do it. However, most of the devices that are plugged in do not require very tight timing control, reliability, and super-low latency so it isn't an issue. Of course, Windows has it's own latency issues but that wasn't your question.
You need a real-time communication link and a real time operating system. Probably a simplification/generalization, but that's the basic idea.
Yes, there are USB motion controllers out there, but from what I understand the timing-critical stuff isn't happening over USB.
Someone do correct me if I'm wrong, but I've actually tried to write my own motion controller that uses USB and wasn't able to get beyond a certain point because of these limitations.
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04 Feb 2017 23:21 #87317
by tommylight
Replied by tommylight on topic Software control
Sparky, nicely said, thank you.
USB is .....well usable for some things, but unusable for others. There is a member here that did something usable with it, DaBit is his nick name here and on youtube, so have a look.
USB is a single line of comunication and that impies a lot of waiting, FIRE WIRE had 2 lines of communication that is why it was used in DV camcorders, USB was unusable for transfering 13 GB of information reliably in an hour.
Regards,
Tom
USB is .....well usable for some things, but unusable for others. There is a member here that did something usable with it, DaBit is his nick name here and on youtube, so have a look.
USB is a single line of comunication and that impies a lot of waiting, FIRE WIRE had 2 lines of communication that is why it was used in DV camcorders, USB was unusable for transfering 13 GB of information reliably in an hour.
Regards,
Tom
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06 Feb 2017 16:28 #87407
by andypugh
That's not really a workable configuration, largely because GRBL is a motion controller, just like LinuxCNC is.
You would use one, or the other.
Replied by andypugh on topic Software control
I plan on building the, Openbuild OX machine, with LinuxCNC Wheezy, and was looking for some insight on control hardware!
The choice I was looking at is Arduino with GRBL shield. Would this be a good option
That's not really a workable configuration, largely because GRBL is a motion controller, just like LinuxCNC is.
You would use one, or the other.
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