Only the outputs power supply should be cut off from the Estop circuit and in some cases only the outputs that activate the main power and circuit enable the axis and spindle drives and the devices that have to be stopped in case of Emergency stop . The inputs power supply is usually not under the Estop circuit control.
Alex Il giorno 08/nov/2014 17:41, <p...@wpnet.us> ha scritto: > This is how I have it setup on the CNC lathe refit I've been working on. > Using 120V on estop only because the relays that came with the machine were > 120v coils, so use what I've got. PC/monitor power is the only thing not on > the estop system, just the main machine power switch. Push the "Machine On" > green button and it switches on power to the spindle VFD and the axis and > field I/O power supplies. Hit the estop button and all of that drops. I'll > ultimately tie it in to a signal line to HAL to let LinuxCNC know if the > machine is on or estopped. Simple and reliable, and also pretty much the > same as the estop on my larger commercial CNC mill (not retrofitted yet). > > > > ------Original Mail------ > From: "Dave Cole" <linuxcncro...@gmail.com> > To: <emc-users@lists.sourceforge.net> > Sent: Sat, 08 Nov 2014 12:01:13 -0500 > Subject: Re: [Emc-users] A beginners question about E-Stop and Charge Pumps > > I do commercial machine controls and the Estops are usually over thought > by the newbies. First of all, the Estop on the LinuxCNC screen and > Mach3 screen is not an Estop and has nothing to do with a safety Estop > system. (System Enable would be a better name) > > A minimal Estop system has a sealed in mechanical relay. There is a > "power on" button (I usually use a Green lit pushbutton - LED is best) > that pulls in the relay and a relay contact on the same relay seals in > the circuit. An Estop is initiated by a pushing in (and latching) a Red > Estop button which has a NC (normally closed) contact. The button must > be twisted to release the latch. > > I usually use 24 vdc control circuits as that is the industry norm > now. But this could also be done with 120 VAC as was common in the old > days. > > The sealed in "Estop" relay supplies power or control power to all of > the contactors, and relays, or simply the devices that move the machine > and tools. > > If LinuxCNC hal is tied into the Estop system, it is only to inform > LinuxCNC that a hard Estop has occurred. The Estops basic purpose is > to cut power to the machine when an Estop button is pressed and cut the > power connection to the machine if the power goes out long enough for > the relay to drop out. (So the machine doesn't restart after a power > outage by itself.) If you have brakes on the machine those (in general) > engage when the power is cut. > > Estop Pushbuttons - the twist to release buttons are required by most > safety standards. Lit Estop buttons with twist to release is common so > it can be wired such that the button is lit when the estop button is > depressed and latched. That way it is obvious which button has been > pushed in and that the Estop system has been activated. > > Here are some parts: > > http://www.automationdirect.com/adc/Overview/Catalog/Pushbuttons_-z-_Switches_-z-_Indicators/22mm_Plastic/Emergency_Stop_Pushbuttons_Illuminated_-a-_Non-Illuminated > The Metal 22mm buttons are worth the few extra $. Note that they sell > latching-twist to release, and momentary. Two different things. > > Really nice power relays.. I've purchased hundreds and have yet to find > a bad one. > > http://www.automationdirect.com/adc/Shopping/Catalog/Relays_-z-_Timers/Electro-Mechanical_Relays/Square_-z-_Cube_Relays,_Plug-In,_3A_-_15A_%2878x-z-_Qxx-z-H78x_Series%29/General_Purpose,_15A_%28781_-z-_782_-z-_783_-z-_784_Series%29/784-4C-24D > > A nice power on momentary button that is illuminated. It can be wired > such that when the system is "On" and the relay is in, the button is lit. > > http://www.automationdirect.com/adc/Shopping/Catalog/Pushbuttons_-z-_Switches_-z-_Indicators/22mm_Metal/Illuminated_Pushbuttons_Flush_-a-_Extended/LED/GCX1202-24L > > For the quality of these devices, these are really inexpensive. > > More info on Estop systems and requirements. > > http://machinerysafety101.com/2009/03/06/emergency-stop-whats-so-confusing-about-that/ > > The diagram on page 11 is close to what I am describing wiring wise. > Replace the reset with the Power On button, The C Aux NC contact is not > normally used in this country. > The ER relay is the sealed in relay. > > > http://www.infoplc.net/files/documentacion/seguridad_normativa/infoPLC_net_THE_EMERGENCY_STOP.pdf > > This document says that force guided relays (Safety relays) are > required. In the US that depends on the company standards, the type of > machine being controlled etc. > > For personal use and a lot of commercial/industrial use in the US, just > using a decent relay often suffices and meets insurance company > requirements, etc. Force guided safety relays start at about $80 each. > > Dave > > > > > > > > > > > > > > > > > > > On 11/7/2014 5:34 PM, Bruce Layne wrote: > > You shouldn't use integrated circuits to implement the AND logic. > > Instead, use relay logic. > > > > The output from the BOB that represents the internal E-stop state in > > LinuxCNC is wired to a relay. If the BOB can't source enough current to > > drive the relay, you might need to use a small relay to operate a larger > > relay, but you don't need a high current relay for the relay logic. You > > only need a small "ice cube" relay and the BOB output should be able to > > drive it directly. If you select a relay with normally open and > > normally closed (NO and NC) contacts, you can select the correct set of > > contacts as you wire it to negate any signals that may be an opposite > > logic state than you assumed. That's a handy feature for flexibility and > > can come in handy for future add-ons. It's easy to make one wrong > > assumption about signal polarity and have the opposite of what you need > > at the final relay in the circuit, and having NO and NC contacts on your > > relay is never having to say DOH! > > > > The logic relay that represents the LinuxCNC internal E-stop state is > > wired in series with any E-stop switches you installed. That way, if > > you push any E-stop switch, or click the E-stop button in LinuxCNC, the > > machine goes into an E-stop state and all motion stops. The signal that > > passes through the E-stop switches and your small relay contacts then > > operates a larger power relay that supplies power to all motion control > > (spindle, steppers, etc.). This power relay can have multiple sets of > > contacts, so each motion producing device can be controlled separately > > if they use different voltages. A set of contacts can be used to > > control your Hitachi router. Another can control the stepper motor > > powers supply or power supplies. > > > > You can also include a set of contacts to control a digital signal that > > feeds back as an input to the BOB so LinuxCNC can determine that you > > pressed an E-stop switch, although for my simple machines like routers, > > I generally don't bother because that takes a bit of messing around in > > HAL, and I like being able to install a new copy of LinuxCNC, select a > > generic stepper gantry router configuration, tweak the machine limits > > and steps per inch, and Bob's your uncle. I don't plan on pushing the > > E-stop switch, and if I do, I don't mind if the program keeps running as > > long as the motion stops. I'm going to reset everything, anyway. > > > > Similarly, for a simple machine, you might skip the relay that > > externalizes the internal LinuxCNC E-stop state. You'll probably press > > a physical E-stop switch on the machine, but clicking the E-stop button > > in LinuxCNC would still stop the motion even if it didn't generate a > > real E-stop. The difference is, the motors would still be powered and > > would be holding position, potentially keeping the operator pinned. If > > you trained everyone to ignore the E-stop button in LinuxCNC and push > > the E-stop mushroom head switch on the machine, it wouldn't be too much > > of a safety problem IMO. If it's an emergency, the operator shouldn't > > be mouse clicking or trying to press hot keys on the keyboard, and I > > don't think they should be trusting any PC software, even if LinuxCNC is > > very robust. I don't believe in software E-stops. > > > > If I was wiring it, I'd probably use a solid state relay ($6 each or > > less on eBay) for each motion device I needed to control and use the > > E-stop signal to control them all. I know they'd work for the 120VAC > > power for your Hitachi router and the DC power supplies that dive the > > stepper motors. If I had any three phase devices, I'd use a three pole > > relay (actually, a motor starter) to ensure that all three phases were > > switch on and off at the same time. > > > > If you do an online search for E-stop circuit, I'm sure you can find a > > lot of circuit diagrams that are wired as I'm describing. There will be > > minor differences depending on the specifics of the machine hardware, > > but the basic concept is the same. Use those as examples and draw > > something similar for your machine. > > > > Good luck! > > > > > > Bruce > > > > > > > > > > On 11/07/2014 04:30 PM, Joe Hildreth wrote: > >> Bruce, > >> > >> Thanks for taking the time to explain it to me. > >> > >> So I can take this approach then: > >> > >> 1) Use the internal E-Stop as an output on the BOB (Use this as in > input to my AND gate) > >> 2) Use the external E-stop which is normally closed as the second input > to my AND gate) > >> 3) Use the output of the Charge pump signal from the BOB as the third > input to the AND gate. > >> > >> 4) The output of the AND gate to drive the TTL inputs of my AC Relays > to enable/disable power to the motors. > >> > >> This way, I still have both E-Stops (Or additional ones by cascading > E-stops) and the charge pump signal to rely on? > >> > >> I could make a PC board for an AND gate with Vcc and ground in with a > decoupling cap and just bring the inputs and out puts to screw terminals. > This way, it would be nice and modular, cheap and fit in any corner of my > electronics drawer that slides in the computer rack. > >> > >> My spindle is a Hitachi router, so not sure if it is even possible to > brake. It will get wired to a SuperPID so that I can control on/off and > motor speed via software. I need to look at the documentation and see what > I have available in terms of E-Stop control. It may be that I have to > treat it like the stepper driver power supplies. I am just not there yet. > I still consider myself a newbie so am trying to take it in digestible > BYTES. > >> > >> As far as the external charge pump. I am thinking that LinuxCNC will > only generate the carrier frequency (charge pump signal) when it has > control. This way if the computer hangs or crashed I would at least have > an additional level of safety. Or am I just over thinking it? > >> > >> One more question. If I wired it like my last email, then LinuxCNC > would not have any clue that I hit the external E-Stop. Would it be > benifitial to bring the signal back in anyway, just to let the software > know we killed it externally? Otherwise, I imagine that the software will > continue to send motion information and continue to plot like nothing ever > happened. > >> > >> > >> Thanks again for your help. > >> > >> Joe > >> > >> ----- On Nov 7, 2014, at 2:35 PM, Bruce > laynelinux...@thinkingdevices.com wrote: > >> > >>> Hi Joe, > >>> > >>> The industry preferred method of implementing an E-stop would be the > >>> opposite of what you propose. Rather than using the mechanical E-Stop > >>> switch as an input and logically ANDing the external E-stop switch and > >>> the internal E-stop machine state, you should use the internal E-stop > >>> machine state as an output and use electronic hardware (relay logic) to > >>> AND the E-stop switch and the E-stop machine state to enable the > spindle > >>> motion and the X/Y/Z motion. To be clear, you're actually ANDing the > >>> non-E-stop conditions, or NANDing two E-stop signals. However you want > >>> to say it, motion should only be possible when the PC based controller > >>> says it's OK to run, and when the E-stop switch says it's OK to run. > >>> > >>> The issue is the reliability of computer hardware and software. These > >>> have greatly improved, but are still not up to the reliability > standards > >>> of relays. > >>> > >>> I like solid state relays, although E-Stop relays are usually clackity > >>> relays with mechanical contacts. > >>> > >>> Consider using multiple E-stop switches if someone could be pinned by > >>> part of the machine. Try think of all of the things that could go > wrong > >>> and make sure someone could quickly reach an E-stop. > >>> > >>> When wiring your E-stop circuit, make sure the E-stop switch contacts > >>> are closed when you want the machine to run, and open when the E-stop > >>> switch is activated. That way, if there is any loose connection in > your > >>> E-stop circuit, the wiring fault causes the machine to fail in the > >>> E-stopped condition. > >>> > >>> The simplest E-stop wiring would cut power to the spindle motor and all > >>> of your stepper motor power supplies, even though the spindle could > >>> probably be actively stopped faster if left under power and commanded > to > >>> stop rather than coasting to a stop. > >>> > >>> Bruce > >> > ------------------------------------------------------------------------------ > >> _______________________________________________ > >> 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 > > --- > This email is free from viruses and malware because avast! 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