On 4/23/2012 1:20 PM, andy pugh wrote: > On 23 April 2012 17:52, Viesturs Lācis<viesturs.la...@gmail.com> wrote: > > >> Is kinematics module the only place, that limits max number of joints? >> The thing is that I suspect that there are other places as well that >> have hardcoded max number of joints to be less or equal to 9. >> > There almost certainly are, but changing that is probably one task for JA3. > > >> LinuxCNC still has only 9 axis words (I have been wishing for more - I >> have a client, who might be interested in LinuxCNC, if it was capable >> of handling production lines with up to 40 independently moved joints >> > The problem is not in LinuxCNC but in G-code. All commands are a > single letter, and there are none left to be extra axis commands. > > With a different interpreter it might be possible to find a way to > command more axes. > > If you only want to control more joints, then you could, in theory, > control them with M67/M68 commands. num_aio defaults to 4 with a max > of 16, but that can be changed in the source. > I think that an M68 will hit the setpoint at the end of the next > motion command (ie, synched to motion) but would need to test it to be > sure. Combined with Limit3 and lots of stepgens/PIDs that would allow > control of a large number of actuators. > >
For most of the machines I run into, other than intense machining cells, the number of axis that need coordination is usually no more than 3 or 4. Most of the other axes are tool loaders, part loaders/indexers, conveyor indexers etc. There is no reason why you cannot use the interpreter for the coordinated axes and then setup other uncoordinated axes in Hal and drive those with Classic Ladder, or some assemblage of Hal and Classic Ladder. Custom hal components are easy to make using Comp and can really expand the capability of hal. If you need to drive more axes and need to serve more cells, add more PCs and link them together with Modbus TCP. The Client and Server is included with Classic Ladder. (I haven't tried it yet - but it is there.) I frequently use the Modbus RTU link. Breaking up a "problem" into smaller pieces and "cells" that are linked, is usually a better solution than having one controller handle a large number of axes. I worked on an aerospace job last year that had about 50 axes of coordinated motion. The machines ended up at NASA. It took 4-6 guys 4+ years to do the software for the controls for the machine. It was all custom and very much bleeding edge. It used a Delta Tau rack controller with two racks linked via fiber optics to handle all of the coordination. By the end of the project, everyone was wishing for something simpler. It was a very difficult machine to debug. I only worked on a portion of the control software for 4 months. Dave ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
