> ... > > > What's everyone else doing? > > > > For the emergency stop I would buy a real emergency button and connect so > > that power is cut to make machine stop. Then pressed it should also be > > sensed so that emergency stop in Linuxcnc is toggled. I would not trust > > emergency button in Linuxcnc, the computer may stop responding for many > > reasons. An extra switch maybe with personal padlock might also be good > > then working with the machine, Injection mold machines at least sometimes > > also have a mechanical lock. > > The ESTOP circuit is still set up the way it was in the original hardware. > The NC ESTOP switch routes control to the AC contactor relay. There's a > second NC contact that is sensed by the BoB and the system. The main > contactor control circuit runs through a second NC ESTOP switch and also > through a relay controlled by the BoB and therefore from the LinuxCNC Enable > button. > > So either an operator generated ESTOP or a LinuxCNC generated ESTOP will open > the circuit to the main AC contactor. As will a broken wire in that chain.
This seems good. > > Programming errors or other logical errors are common. Safety circuit should > > be simple to check and understand though there might also be a cases there a > > complex sequence which must work to keep alive is suitable, I would guess to > > succesfully reading a bar code or QR code to keep alive could be made so > > that > > likelyhood for an error in wrong direction is very low. > > > > Put a toggle signal in Linuxcnc, send it out on all motor driver outputs to > > a > > transformer connected to a safety relay which is connected in series so that > > power is cut if signal is not regularly toggled would probably add some > > safety > > but in case encoder signal is lost a servo drive is likely to move to one > > of the > > end stops. > > > > My softstart is controlled by a small 8 pin PIC. This s the same processor > that also does the over voltage clamping and automatic fast drain of the > power supply on loss of AC power. I can use that softstart signal to gate > the enable to the STMBL drive. Even though it's unlikely it could fail. Commercial drives use to have a safe torque off input. I expect it work for AC motors but if a DC motor is overloaded semiconductors usually fail with short so it could run at full speed in one direction even if control signals are turned off. Most of the time I expect no one is in the danger zone but if it is likely someone is in the danger zone then emergency is activated it is important it could be trusted. Misstakes happens but otherwise there is a reason to press the emergency stop. _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
