I'm about to wire in an NVR (No-Volt Release), i.e. a latching relay, set by a momentary pushbutton [1], but have a couple of questions:
A) Is it safe to interrupt Motor Power to my 7i40s, with hairy great inductive motors on their outputs? (OK, mostly resistive under load, but then back EMF might also be deadly if V+ is open-circuited?) I can't use the 7i40's active low enable inputs, because they're in the ribbon cable to the 5i20. That means we have to go via the 7i37 inputs and the EMC2 software, if we're to avoid potentially stressing the 7i40s. Ah ... maybe interrupt Motor Power before the filter capacitors? That leaves somewhere to dump back EMF, and should be gentler on the H-bridges. (A bit rough on a relay though, with zero volts on the capacitors at start-up. A fat MOSFET would handle it better.) B) What about a charge-pump? i.e. Estop if the controller goes down or loses the plot. Or does the 5i20 do that in the FPGA? I've read the "5i20 Anything I/O Manual", but the Hostmot2 section is a bit thin. (Re the wiki, see below.) But even if the 5i20 does disable the 4 H-bridges, that still leaves the spindle whirring away. Does it tell EMC, so that I can "net estop-out => some_7i30_output", to interrupt the Estop chain, and cut spindle power as well? Finding only http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?EstopChain in the wiki, which just points to http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?MazakEstopChain , I wonder if: C) Is the HAL "estop latch" mentioned there just FYI? Point 26 raises the issue of ESTOP_RESET, but point 27 says "ESTOP_RESET comes from the core of EMC, and is asserted when the machine is taken out of ESTOP (by hitting F1)." So there appears to be no physical input needed for that. (But maybe I should spraypaint F1 green.) D) Have I missed (in the wiki) a concise schematic showing a typical Estop chain, useful relay contacts, and estop-in & estop-out wiring and HAL config? Or is that a ToDo that I'm cheerfully walking into? ;-) I hope that I'm expressing all that clearly, it's nearly midnight here. Erik [1] I'll try to use the existing Big Red Button on the mill, even if I have to add a relay in the control box, to gain a free pair of output contacts to go to the Estop chain. -- You really HAVE to have a hardware E-stop! - Jon Elson on emc-users, 14 Jun 2008. ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
