[Home]History of HardwareDesign

LinuxCNCKnowledgeBase | RecentChanges | PageIndex | Preferences | LinuxCNC.org

Revision 6 . . November 29, 2016 3:33 pm by KimK [Standardize capitalization of LinuxCNC, USB. Fix minor typos.]
Revision 5 . . (edit) March 20, 2016 4:09 pm by Cmorley
Revision 4 . . (edit) March 12, 2016 12:08 pm by Cmorley
Revision 3 . . (edit) March 12, 2016 12:08 pm by Cmorley
Revision 2 . . March 12, 2016 12:07 pm by Cmorley [another common question answered]
Revision 1 . . October 28, 2014 1:06 pm by JeffEpler
  

Difference (from prior major revision) (no other diffs)

Changed: 50c50
Several people have had positive experience with "uspace" realtime and UDP ethernet communication. However. realtime ethernet performance depends on the Linux network driver itself having good realtime performance.
Several people have had positive experience with "uspace" realtime and UDP ethernet communication. However, realtime ethernet performance depends on the Linux network driver itself having good realtime performance.

Changed: 62c62
Many PCs have a common, easy-to-program chip for RS232 serial interfaces, the 16550 FIFO. However, the top speed is 115200baud. In 200us, only 16 usable bits can be transmitted in each direction (10 bit times per character, 2 characters = 173uS), which is not enough to send DAC commands and retrieve position feedback for multiple axes.
Many PCs have a common, easy-to-program chip for RS232 serial interfaces, the 16550 FIFO. However, the top speed is 115200 baud. In 200us, only 16 usable bits can be transmitted in each direction (10 bit times per character, 2 characters = 173uS), which is not enough to send DAC commands and retrieve position feedback for multiple axes.

Changed: 68c68
because it breaks the idea of the project - Linuxcnc as a machine controller.
because it breaks the idea of the project - LinuxCNC as a machine controller.

Changed: 72,75c72,75
If you wished to do rigid tapping with your usb based controller - you would have to add the tapping code to your microcontroller.

USB wil not allow reliable communication between the motion controller (linuxcnc) and the motor controller (your micro)

multiply that by other options and now you have basically made your micro controller into a motion controller.

This has been done in a fork of linuxcnc - usb to a mesa 7i43 card. araisrobo project (now uses machinekit IFAIK)

If you wished to do rigid tapping with your USB-based controller - you would have to add the tapping code to your microcontroller.

USB will not allow reliable communication between the motion controller (LinuxCNC) and the motor controller (your micro).

Multiply that by other options and now you have basically made your micro controller into a motion controller.

This has been done in a fork of LinuxCNC - USB to a mesa 7i43 card in the araisrobo project (now uses machinekit AFAIK).


Changed: 77,78c77,78
Now if someone added some cool option to linuxcnc's motion controller you won't able to use it until you added it to your motion controller.

It also doesn't allow linuxcnc's builtin scope and meters access to the micro controller's internal test points.
Now if someone added some cool option to LinuxCNC's motion controller you wouldn't be able to use it until you added it to your motion controller.

It also doesn't allow LinuxCNC's built-in scope and meters access to the micro controller's internal test points.

Changed: 80,81c80,81
By using relatively 'dumb' hardware, we avoid that scenario - what ever linuxcnc can do it can do with all hardware that supports the basic requirements.

You can even run an analog servo using the parallel port - just the performance would be low.
By using relatively 'dumb' hardware, we avoid that scenario - whatever LinuxCNC can do it can do with all hardware that supports the basic requirements.

You can even run an analog servo using the parallel port - just the performance would be low.


Changed: 83c83
So is it a waste of time for simple I/O stuff? yes I guess you could say that - but when you look at the bigger picture it makes sense - linuxcnc does a lot more then just simple step driven mills.
So is it a waste of time for simple I/O stuff? Yes, I guess you could say that - but when you look at the bigger picture it makes sense - LinuxCNC does a lot more than just simple step driven mills.

Changed: 85c85
We prefer that the motion controller is in one place - linuxcnc.
We prefer that the motion controller is in one place - LinuxCNC.

LinuxCNCKnowledgeBase | RecentChanges | PageIndex | Preferences | LinuxCNC.org
Search:
Published under a Creative Commons License