On Saturday 10 August 2019 00:57:29 Chris Albertson wrote: > My opinion: If the e-stop system is so complex that its design is > not simple and obvious then it is to complex to be safe. > > E-stop has to be so simple it is completely foolproof and design such > that if some part of it fails, like a wire comes loose then the system > stops. In other words, it needs to fail-safe. > > A good example is that all the "enable" pins on all the motor > controllers are held in the "enable" state by a power supply. So now > if the supply fails or the wires connecting it fail the motors all > stop. In other words the e-stop's job is to NOT stop the machine but > to enable it's operations > > Then when you press an e-stop button the button breaks a connection. > > If you are using complex logic the design is to complex to be 100% > safe. Ask youself, what would happen if part of the e-stop system > failed or was designed wrongly? the answer has to be "all the motors > stop".
And one final point, since the e-stop is by definition unscheduled, the machine should be un-homed by that stop. Steppers in particular, will have no clue where they are when re-enabled next. That you can/must do with a hal net statement, but the rest of the circuit should be hard wired. The little 7x10 lathes have a two pole switch that sells for about $15 from LMS, must be unlatched and opened to enable both contacts, in an emergency a fist brought down on top opens both contacts and mechanically latches it open. I can't think of a better yet cheap switch for that job. > On Fri, Aug 9, 2019 at 4:29 PM andrew beck <andrewbeck0...@gmail.com> wrote: > > Hi guys > > > > Just want to say thanks for the help with the e stop circuits. All > > the replies were amazing > > > > I have all the relays working now but am stuck on classic ladder. > > > > I Don't actually know how to load it and do the most basic things > > > > Can someone show me how to start with the most basic things like > > actually opening the program please. Or link me to any videos of > > the process > > > > Regards > > > > Andrew > > > > On Mon, Jul 22, 2019 at 12:30 PM Gregg Eshelman via Emc-users < > > > > emc-users@lists.sourceforge.net> wrote: > > > Emergency Stop buttons are made so that the knob locks in when > > > pushed and has to be rotated to unlock it so it can come out. > > > Breakout boards, VFDs, and various other machine control equipment > > > often has E-Stop inputs which can be wired in a circuit so one or > > > more buttons can be used to stop everything. > > > > > > The easiest way to setup an E-Stop circuit is to have everything > > > with an E-Stop connection require a voltage input, then wire them > > > all in series with one or more stop buttons. Hit any button, it > > > opens the circuit to everything. Needs no relays, no electronic > > > circuitry (outside of the breakout board etc), just dead simple > > > wire and lock open switch(es). You can add an enable switch to the > > > E-Stop circuit, with a relay that's held closed by the E-Stop > > > power. Then it's a 2 step process to re-enable the machine. Turn > > > the E-Stop switch button to close it then press the enable button > > > to close its relay. That button will also need pressed when > > > starting the machine from powered off. It won't latch on if an > > > E-Stop button is still locked open. > > > > > > On Sunday, July 21, 2019, 5:12:08 AM MDT, andrew beck < > > > andrewbeck0...@gmail.com> wrote: > > > I need to set up a latching relay somehow to make sure the E stop > > > > doesn't > > > > > turn back on until I turn it on within linuxcnc. > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
