> > -----Original Message----- > > From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com] > > Sent: April-08-18 9:52 AM > > To: Enhanced Machine Controller (EMC) > > Subject: Re: [Emc-users] ESTOP and Drive Enable handling. (SAFE OFF) > > > > On Wed, 4 Apr 2018 12:57:03 -0700 > > "John Dammeyer" <jo...@autoartisans.com> wrote: > > > > > In the past ESTOP appeared to be pretty simple a 12V or 24V control > signal > > was routed through any number of Normally Closed (NC) switches and then > > run into relays and or opto-isolated inputs. Any ESTOP even would then > > interrupt the control voltage and relays would open dropping all power. > > > > > > However things have changed a bit. With PCs in the mix, rules changed > > and PCs and control systems could stay active but anything in hardware > > dangerous to humans was now switched off by the signal interruption. > > > > > > Enter a wide variety of motor controllers. The HP_UHU has an active low > > ESTOP IN/OUT signal. A low on the ESTOP input shuts off power to the > > drive control logic. If the drive has a fault, it brings this line low > too and any > > other HP_UHU drives are also then pulled into ESTOP mode. I think this > > would be better identified as ENABLE rather than ESTOP. > > > > > > The STMBL AC Servo drive I'm currently working with has an ENABLE high > > input. So when Low it's disabled and stepping pulses can't move the > motor. > > > > Then working with frequency inverters I come upon the term "safe torque > > off" and are pretty sure there are special requirements on this signal. I > think > > this particularly apply to DC motors since failure mode close may cause it > to > > run at full speed. > > I believe that the ESTOP signal should remove power to relays that supply > energy to anything that could hurt a human. That means, motor voltage, > heater voltage, lasers and pneumatics. Once the ESTOP is released that > same set of relays must require a separate action to re-enable them. SO > that someone doesn't just release the ESTOP and a motor starts up cutting > through the rest of a man's arm for example.
Yes I think so to but other means might also be good enough. I worked at a quite handy machine for some time, just put a piece of wood inside and press the pedal. I still have all arms, hands and fingers as do the man who worked there before but one misstake and it would hav been gone. > Keeping the ENABLE as a switch that must be cycled off and then on allows > the software to also disengage all motion. Then, if safety warrants it, the > drives can be re-enabled and JOG feature used to pull back our out or away > from the human pinned by it. Way back when I worked in The Netherlands > there were pretty strict rules about what ESTOP did and how equipment > behaved after ESTOP was released. I don't know what the regulations are > now. I think they still are strict. > And ideally the separate ESTOP circuit must be Normally closed so a broken > wire has the same effect. I think so to. I also think some electronic devices may be approved but it's incredible hard to check something invisible so I think they leave this to the manufacturer. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
