I dont't think it is entirely impossible and that hard. You just need to enumerate a few times with the USB device and write an interlayer software that will be the hardware part for the EMC. Commands sent to the USB device have to be true commands, not just single steps, and the feedback to the EMC needs some tuning too. Depending on how much you aggregate the microfunctions into the sent commands and how responsible your USB communication will be - the same will be the success rate - the USB needs to respond quickly, so that the software driver on PC will be able to correct its behavior.
Since there are external controller boards and demuliplexers available for use with EMC, it should too be possible to do with USB device with some minor limitations - the USB is for toy devices, so I expect your machine will be of the class, not a 5kW, 5 ton mill. I forgot the name of the few external controller boards that are supported on EMC, but if you look at their drivers, you might get a hint how to do that. Learn more about the timers that are used in EMC2 and think about how much time do you need between communication steps, etc. Typically, if you would be putting out analog values, like the output of PID loop to motor current control and have input of precisely measured motion feedback, etc, you would only need the outer loop control, for say, 100-200Hz interrupt rate. All you need is to know how to make an USB microcontroller program with proper stack management and enumeration without an error. Also you have to design it very responsible, quick to execute. PIC 18F or the new PIC 24-bit code class with USB might be suitable for this due to strict timing and exact time execution. On the PC side you have to make some corrections to the output driver in the EMC2 - it has to be able to tell how many steps to make, the same for input. Mario. On 4/23/07, Till Harbaum / Lists <[EMAIL PROTECTED]> wrote: > Hi, > > Am Montag 23 April 2007 schrieb John Kasunich: > > But there are still issues. When you hit stop, does it stop NOW, or > > after it works its way thru the queued motion? If you are doing > You have at least two choices here: a) send some special emergency stop > command that overrides the buffers or b) Have the interface handle these > directly and just report to the PC that this happened. > > > While that is possible, what you would end up with would not be EMC. It > > would be a CNC controller based on a totally different architecture. > Sounds like too much work. > > Till > > ------------------------------------------------------------------------- > This SF.net email is sponsored by DB2 Express > Download DB2 Express C - the FREE version of DB2 express and take > control of your XML. No limits. Just data. Click to get it now. > http://sourceforge.net/powerbar/db2/ > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
