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| raynerd:
I don`t really have knowledge here but why is it that cnc still use parallel and has never moved over to usb directly? I must not have used a parallel port for a printer in over 6 years, so why hasn`t cnc switch over. Is USB some how limited when it comes to real time? Chris |
| kwackers:
--- Quote from: craynerd on March 02, 2012, 05:34:55 AM ---I don`t really have knowledge here but why is it that cnc still use parallel and has never moved over to usb directly? I must not have used a parallel port for a printer in over 6 years, so why hasn`t cnc switch over. Is USB some how limited when it comes to real time? Chris --- End quote --- Because parallel is just a port - with a bit for each wire and stepper motor drivers need two wires each, one to step and one to set direction. You could make a usb to stepper driver type device but if you go to that sort of trouble why not just make the device read the g-code directly and drive the lines itself? At which point why bother with the computer? |
| David Jupp:
There are usb devices in existence which off-load the work of pulse generation from the PC (a significant task) - these allow Mach3 to achieve much higher step rates than is possible when the PC is doing all the work (or perhaps mean you don't need quite such a fast PC). The PC sill manages user interaction and G-code 'translation'. Parallel port was originally used 'because it was there'. The Raspberry Pi could potentially work with one of these USB devices, or the onboard I/O options could be used to send pulses to stepper drivers. |
| BillTodd:
--- Quote from: BillTodd on February 29, 2012, 09:16:07 AM ---Anyone actually manage to buy one a Raspberry Pi today? At £22 they look like a nice cheap development board - I can think of several uses for one now, IF they were available ! Bill --- End quote --- |
| Bluechip:
It appears EPE are going to have a gander at the thing : http://www.chatzones.co.uk/discus/messages/7/13258.html?1330774601 Might even suscribe ... Hmmmmm .. BC |
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