On Sunday 21 July 2019 13:40:53 andy pugh wrote: > On both my machines I took the decision to rely on LinuxCNC to handle > the latching, but to have the E-Stop button directly cut power to the > drives. This might not be the best system to use for 100% coverage of > software failure modes, but these are hobby machines. [1] > So, LinuxCNC closes the contactor that feeds the servo PSU and the > VFD. The wiring for the control solenoid of that contactor loops > around the machine to the single e-stop on the lathe and both those on > the mill. In the case of the mill the switches have a second NO > contact block that signals to LinuxCNC that the e-stop has been > pressed, and that toggles the software e-stop in LinuxCNC through HAL. > The lathe uses > halui.estop.activate wheres the mill uses iocontrol.0.emc-enable-in. > On reflection it would probably be better to use a realtime pin from > the motion module, in theory both iocontrol and halui are susceptible > to user-space lock ups. But then if that has happened then, whilst > motion is likely to still be running fine, the signals to the rest of > the system from there are not guaranteed anyway. > > On the lathe, rather than use a second contact on the e-stop switch > itself I use an auxiliary contact on the contactor to signal the > e-stop state. I confess I have forgotten how I did it, whether HAL > logic detects the contactor being powered but the auxilliary contact > being open, or whether it is an NC contact that supplies 24V to the IO > input from the solenoid control voltage if the solenoid is powered but > NC contact has remained closed. > > > [1] Arguably this means that they should be built to an even higher > standard. If I get tangled in my machines _nobody_ is coming to help.
Same here Andy. Tends to keep me alert, but we both know that is not a guarantee. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
