> > ... > In an open-loop step/direction system, there is no way to > know a stall happened, except to operator hitting the > E-stop button (if he is watching!) And, after any E-stop, > you need to rehome the machine. > > But, if you have encoder feedback to the CNC control, then > you can detect stalls and never lose the > axis alignment. > > You can't just send 10,000 steps to totally independent > motor drives, as they will almost certainly not arrive > at the endpoint at the same time (especially if one drive > gets 10,000 steps and the other gets 4321 steps.) > > Jon
You need to synchronize them then you could send many points, in doubt 10,000 steps is a good idea but maybe up to 20 to 50 fifty if sent is used at a rate of 1kHz and good response is needed in user interface. For response in user interface I assumed queue have to be used up before reaction will happen for example then jogging. If messages are sent over Ethernet it make sense to put several values in each message since header most probably is relatively large compared to values sent. There should be no problem sending feedback using FIFO except delay though there might be a point reducing rate for feedback to message send frequency. Feedback with encoder should work but signal will be delayed which most likely will be a problem for feedback unless this is done locally in device. If following error is checked in Linuxcnc delay need to be added on compared signal but it may also be done locally in device. Using feedback in display sending at display update rate will obviously be preferred. Regards Nicklas Karlsson _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
