USB
23 Jun 2016 13:30 #76490
by Reggie
Hi new to Linux cnc.
Simple question from my first posting.
Can Linux cnc can USB be used with Linux cnc I instead of DB 25 port.
I have been using Mach for some years but want to change over to Linux cnc mainly because of the screw-cutting problems with Mach.
I look forward to any replies.
Reggie
Simple question from my first posting.
Can Linux cnc can USB be used with Linux cnc I instead of DB 25 port.
I have been using Mach for some years but want to change over to Linux cnc mainly because of the screw-cutting problems with Mach.
I look forward to any replies.
Reggie
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23 Jun 2016 13:44 #76491
by andypugh
No. LinuxCNC relies on a deterministic real-time link between the controller (LinuxCNC) and the hardware.
USB is not real-time (fast is not the same as real-time) so can't be used without offloading the machine control to the USB device.
(The Mach3 / Smoothstepper combo does this, the actual control software is on the Smoothstepper board)
There are, however, alternatives to the parallel port supported by LinuxCNC. A variety of PCI (and even ISA cards) are supported and also systems using Ethernet, EtherCAT, Modbus. There are also some systems that use the parallel port as a communications bus, rather than as individual pins and generate step-pulses (or servo motion) on an FPGA.
wiki.linuxcnc.org/cgi-bin/wiki.pl?LinuxCNC_Supported_Hardware
USB is not real-time (fast is not the same as real-time) so can't be used without offloading the machine control to the USB device.
(The Mach3 / Smoothstepper combo does this, the actual control software is on the Smoothstepper board)
There are, however, alternatives to the parallel port supported by LinuxCNC. A variety of PCI (and even ISA cards) are supported and also systems using Ethernet, EtherCAT, Modbus. There are also some systems that use the parallel port as a communications bus, rather than as individual pins and generate step-pulses (or servo motion) on an FPGA.
wiki.linuxcnc.org/cgi-bin/wiki.pl?LinuxCNC_Supported_Hardware
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23 Jun 2016 22:48 - 23 Jun 2016 22:48 #76521
by BigJohnT
Last edit: 23 Jun 2016 22:48 by BigJohnT.
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24 Jun 2016 12:58 #76548
by Todd Zuercher
Replied by Todd Zuercher on topic USB
There are a few other things usb can be used for in Linuxcnc. Most anything user interface related can use it. It can also be used for other non-real-time critical things such as modbus control of a spindle VFD. But for control of axis motion, no, it isn't good enough.
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