Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
All, I just wanted to take a minute and thank all of you for the help, links, advice, (c). I really appreciate it. I have decided that I will bring the software estop out and use it with the mechanical estop(s) to just drop all the power from the motor drivers, Router, Vacuum, (c). I will also bring the estop condition back into LinuxCNC, not because it really matters, but just so the software recognizes the stopped condition. Again, thanks so much for all you help and advice. I really was over thinking it or something. Having been in computer networking in the healthcare industry for the last 15 years, I have got into the habit of over thinking as part of the CYA you perpetually have to do because the government constantly mandates it. You folk really are a blessing to have as a community. Joe Hildreth -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Coordinating an external E-Stop with LinuxCNC can be done with the ESTOP_LATCH component as described here: http://linuxcnc.org/index.php/english/forum/47-hal-examples/25861-external-e-stop JT On 11/7/2014 3:35 PM, Joe Hildreth wrote: Bruce, 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, Joe -- ___ 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
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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Bruce, Yeah, I suppose I have been beating the horse to death with the questions. Sorry. But hey, when you don't know a lot about it you have to start somewhere, right? Thanks for all the help and clarification. After I sent the email, I went off in search of relay logic circuits. After reading a couple of articles I seen that I had it wron in my head. Talking about easy cheap MC's, I loved the PIC, simple to code, implement and cheap on the wallet. I am off to look for circuit examples. Thanks for being so patient. Regards, Joe - On Nov 7, 2014, at 11:05 PM, Bruce Layne linux...@thinkingdevices.com wrote: Joe, In the words of Roseanne Rosannadanna, you ask a lot of questions! :-) You don't wire the coils of relays in series for relay logic. The coil voltage is selected to match the voltage you want to use to activate it... 5VDC, 12VDC, 24VDC, 120VAC, etc. You wire the relay contacts in series to implement an AND function (as is the case with your E-stop switches and a relay that mirrors the status of the internal LinuxCNC E-stop signal, and any other relay controlled signal you want to generate an E-stop). You'd wire the contacts from different relays in parallel to implement an OR function. The reason I suggested using relay logic for this application is simplicity. You'll need a relay to externalize the internal E-stop status anyway, so just wire the contacts in series with any E-stop switches you have and you're finished. Why add any discrete logic ICs to that? It's needless complexity. I'm generally a big fan of implementing logic in software or firmware. I've replaced a lot of goofy 1950s technology relay logic where relays and electromechanical timers were used in the 1990s because someone didn't know how to use a PLC or (my favorite) a one dollar RISC microcontroller. But if you already have the relay and that's all you need, why add an Arduino to drive the relay? If you search for E-stop circuit and look at the images, you'll see lots of examples and it'll make sense. There are also some standard circuits for input power disconnects (I don't go to that formality for my small CNC machines) with fuses/breakers, ON and OFF pushbutton switches that latch the ON condition until the OFF button is pressed, etc. Bruce -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Dave you are 100% right. Your detailed explanation it`s correct conceptually and practically for an industrial application. Alex Il giorno 08/nov/2014 17:03, Joe Hildreth j...@threerivershospital.com ha scritto: Bruce, Yeah, I suppose I have been beating the horse to death with the questions. Sorry. But hey, when you don't know a lot about it you have to start somewhere, right? Thanks for all the help and clarification. After I sent the email, I went off in search of relay logic circuits. After reading a couple of articles I seen that I had it wron in my head. Talking about easy cheap MC's, I loved the PIC, simple to code, implement and cheap on the wallet. I am off to look for circuit examples. Thanks for being so patient. Regards, Joe - On Nov 7, 2014, at 11:05 PM, Bruce Layne linux...@thinkingdevices.com wrote: Joe, In the words of Roseanne Rosannadanna, you ask a lot of questions! :-) You don't wire the coils of relays in series for relay logic. The coil voltage is selected to match the voltage you want to use to activate it... 5VDC, 12VDC, 24VDC, 120VAC, etc. You wire the relay contacts in series to implement an AND function (as is the case with your E-stop switches and a relay that mirrors the status of the internal LinuxCNC E-stop signal, and any other relay controlled signal you want to generate an E-stop). You'd wire the contacts from different relays in parallel to implement an OR function. The reason I suggested using relay logic for this application is simplicity. You'll need a relay to externalize the internal E-stop status anyway, so just wire the contacts in series with any E-stop switches you have and you're finished. Why add any discrete logic ICs to that? It's needless complexity. I'm generally a big fan of implementing logic in software or firmware. I've replaced a lot of goofy 1950s technology relay logic where relays and electromechanical timers were used in the 1990s because someone didn't know how to use a PLC or (my favorite) a one dollar RISC microcontroller. But if you already have the relay and that's all you need, why add an Arduino to drive the relay? If you search for E-stop circuit and look at the images, you'll see lots of examples and it'll make sense. There are also some standard circuits for input power disconnects (I don't go to that formality for my small CNC machines) with fuses/breakers, ON and OFF pushbutton switches that latch the ON condition until the OFF button is pressed, etc. 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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
John, Thanks for the link. I took a close look at it and then read the man pages for estop_latch and iocontrol. I think I have a grip on it. Well for now. Thanks again for the link. Joe - On Nov 8, 2014, at 6:37 AM, John Thornton bjt...@gmail.com wrote: Coordinating an external E-Stop with LinuxCNC can be done with the ESTOP_LATCH component as described here: http://linuxcnc.org/index.php/english/forum/47-hal-examples/25861-external-e-stop JT On 11/7/2014 3:35 PM, Joe Hildreth wrote: Bruce, 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, Joe -- ___ 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 -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
On 11/08/2014 12:02 PM, Joe Hildreth wrote: I suppose I have been beating the horse to death with the questions. Sorry. But hey, when you don't know a lot about it you have to start somewhere, right? Thanks for all the help and clarification. My pleasure. I've received a fair amount of LinuxCNC specific answers from the good people on this list, and if I can answer an electrical question, I'm happy to have the opportunity to pay it forward. I kept urging you to look for example E-stop schematics because I felt it was the easiest way for you to grok the concepts. A picture is worth a thousand words. The recent post by Dave describes the industry standard way to wire a machine. I've designed quite a few industrial machines just like that. I do cut some corners on machines I use in my basement shop (solid state relays instead of mechanical relays, etc.), but I still adhere to the same basic concepts because that's generally the simplest way to do the job. It also helps to wire it according to standard design principles because that'll make it easier for me or anyone else who has some machine wiring experience to troubleshoot later. Standard methods ensure we're all on the same page. Talking about easy cheap MC's, I loved the PIC, simple to code, implement and cheap on the wallet. I was in early on the PIC microcontrollers, and wrote a LOT of PIC assembler code. I haven't dabbled in that in almost a decade, but I'm about to do a simple PIC project or two. -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
There is only one small field I/O power supply. Estop drops all the power supplies. --Original Mail-- From: alex chiosso achio...@gmail.com To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: Sat, 8 Nov 2014 18:52:41 +0100 Subject: Re: [Emc-users] A beginners question about E-Stop and Charge Pumps 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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
On 7 November 2014 21:35, Joe Hildreth j...@threerivershospital.com wrote: 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. My scheme is similar to those described, the motion.machine-is-on signal is amplified to have enough current to operate the main contactor, then the contactor coil circuit runs through all the e-stops. On the mill the e-stops all have a second switch module that tells the system that the e-stop has been pressed. I don't think that the lathe knows. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] A beginners question about E-Stop and Charge Pumps
Hello everyone, I am sure these questions are asked all the time but I have found nothing that really covers what I am looking for. (But maybe I am not too good with the search.) I have built a CNC Gantry router based on the KRMx01 design from Kronos Robotics. But instead of using the electronics and Mach3 he suggested, I am using electronics, motors and Linux CNC. The basic machine is up and running and I am using it to cut more parts for the machine. I am to the point now that I need to think E-stop, limit and home switches, vacuum control (dust collection) and router PID. My setup is a C10 (cnc4pc) BOB, (4) CW230 stepper drivers, (2) 36vdc power supplies (each feeding 2, CW230 drivers) and (1) 5vdc supply enabling the BOB. The CW230 drivers do not have a charge pump or anything like that, though they do have a pin called REST that according to the sparse documentation says will allow the motor to free spin. (I guess it may be considered an enable) Because I have a couple of teenage boys and a wife who have expressed an interest in using the machine, I need to make sure it can be stopped in the event something unplanned happened. Here is my thought and also where I need some guidance on best practice or acceptable practice. 1) Connect external E-Stop to input pin on controller 2) Use HAL to logic glue the AXIS GUI estop and AXIS GUI Power button together so that IF both E-Stops are on the closed position AND the power is on in AXIS GUI THEN allow charge pump signal on output pin of BOB 3) Connect cnc4pc part C4 (charge pump) inputs to charge pump signal on the corresponding output pin on the BOB. The output of the charge pump is a relay with the choice of NO or NC contacts. If the charge pump frequency falls above or below the operating threshhold, then use this output as a trigger. 4) Connect the output to (2) C8 (cnc4pc part number) AC relays with 5 volt input to connect / disconnect the AC side of the (2) 36vdc power supplies that power the CW230 stepper drivers. In my simple mind, this should provide the following safety feature. A) The machine will only run if both E-Stops (external E-Stop and AXIS GUI E-stop) are in the closed positions AND the power button (AXIS GUI) is on. Allowing the Charge pump signal to be generated on the output pin of the BOB enabling the power to the motors through the Charge Pump and AC Relays. B) If either Estop is opened, then the Charge pump signal will be stopped causing the power to the supplies to be cut by the AC Relays from the Charge Pump. C) If the computer crashes and the LPT port is left in an unknown state, the charge pump signal should be gone causing the power to the motors to be cut. D) Avoid any start up random signals to the LPT port being sent to the motors because the drivers will not be powered up. Kind of long, but am I on the right track here. Just want to have a margin of safety if my boys or wife is trying to use the machine. If you are interested, I have a detailed build of this machine, including screen casts of LinuxCNC hybrid install, configuration to this point, etc on my website which you can see by going to http://myheap.com/krmx01-cnc-router/krmx01-build-log.html I will be adding this (E-Stop, charge pump, AC relays) to the pages too including how to configure and the logic behind the solution. I am hoping it to be a resource to others like me who are only in it on the hobby level and still have the HUGE learning curves to make it over. Many thanks, Joe -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
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 On 11/07/2014 02:46 PM, Joe Hildreth wrote: Hello everyone, I am sure these questions are asked all the time but I have found nothing that really covers what I am looking for. (But maybe I am not too good with the search.) I have built a CNC Gantry router based on the KRMx01 design from Kronos Robotics. But instead of using the electronics and Mach3 he suggested, I am using electronics, motors and Linux CNC. The basic machine is up and running and I am using it to cut more parts for the machine. I am to the point now that I need to think E-stop, limit and home switches, vacuum control (dust collection) and router PID. My setup is a C10 (cnc4pc) BOB, (4) CW230 stepper drivers, (2) 36vdc power supplies (each feeding 2, CW230 drivers) and (1) 5vdc supply enabling the BOB. The CW230 drivers do not have a charge pump or anything like that, though they do have a pin called REST that according to the sparse documentation says will allow the motor to free spin. (I guess it may be considered an enable) Because I have a couple of teenage boys and a wife who have expressed an interest in using the machine, I need to make sure it can be stopped in the event something unplanned happened. Here is my thought and also where I need some guidance on best practice or acceptable practice. 1) Connect external E-Stop to input pin on controller 2) Use HAL to logic glue the AXIS GUI estop and AXIS GUI Power button together so that IF both E-Stops are on the closed position AND the power is on in AXIS GUI THEN allow charge pump signal on output pin of BOB 3) Connect cnc4pc part C4 (charge pump) inputs to charge pump signal on the corresponding output pin on the BOB. The output of the charge pump is a relay with the choice of NO or NC contacts. If the charge pump frequency falls above or below the operating threshhold, then use this output as a trigger. 4) Connect the output to (2) C8 (cnc4pc part number) AC relays with 5 volt input to connect / disconnect the AC side of the (2) 36vdc power supplies that power the CW230 stepper drivers. In my simple mind, this should provide the following safety feature. A) The machine will only run if both E-Stops (external E-Stop and AXIS GUI E-stop) are in the closed positions AND the power button (AXIS GUI) is on. Allowing the Charge pump signal to be generated on the output pin of the BOB enabling the power to the motors through the Charge Pump and AC Relays. B) If either Estop is opened, then the Charge pump signal will be stopped causing the power to the supplies to be cut by the AC Relays from the Charge Pump. C) If the computer crashes and the LPT port is left in an unknown state, the charge pump signal should be gone causing the power to the motors to be cut. D) Avoid any start up random signals to the LPT port being sent to the motors because the drivers will not be powered up. Kind of long, but am I on the right track here. Just want to have a margin of safety if my boys or wife is trying to use the machine. If you are interested, I have a detailed build of this machine, including screen casts of LinuxCNC hybrid install, configuration to this point, etc on my website
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
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? Thanks again for your help. Joe - On Nov 7, 2014, at 2:35 PM, Bruce Layne linux...@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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Bruce, 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, Joe -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
While following this thread, I found these links: http://madpenguin.ca/blog/2012/02/16/an-emergency-stop-circuit-with-emc2/ the above has a brocken link to here: http://www.hs-compliance.com/uploaded/documents/THE%20EMERGENCY%20STOP%20-%202012%20ver%202.0.pdf For spindles, Warner makes a magnetic release brake which brakes when power is cut: http://www.altraliterature.com/pdfs/FB%20Series-Permanent%20Magnet%20Brakes.pdf These fail to a safe condition. eBay can be a good source. A little less fail-safe is braking an AC motor with a DC current: http://www.homemetalshopclub.org/news/sep01/sep01.html http://www.electrical4u.com/induction-motor-braking/ There should be a version for router motors. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/ -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Joe, Your last request is what happens where you hit 'pause', e-stop is for emergencies. It should be used to keep from loosing a hand, or to keep the equipment from tearing itself apart. Pause is to stop in a restartable manner. The machine may have to finish a cut before it can pause, but using e-stop means you are willing to lose the piece or repair it if something is wrong. I hope that helps. ... Jack On Fri, Nov 7, 2014 at 3:35 PM, Joe Hildreth j...@threerivershospital.com wrote: Bruce, 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, Joe -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- ... Jack Whatever you do, work at it with all your heart... Colossians 3:23 Anyone who has never made a mistake, has never tried anything new. - Albert Einstein You don't manage people; you manage things. You lead people. - Admiral Grace Hopper, USN Tell me and I forget. Teach me and I remember. Involve me and I learn. - Ben Franklin -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Jack, Thank you. I see your point. Sometimes I get tunnel vision. Would you recommend the external charge pump in the mix like I suggested? I am thinking that this would just be an extra level of safety. Am I correct? Joe - On Nov 7, 2014, at 4:07 PM, Jack Coats j...@coats.org wrote: Joe, Your last request is what happens where you hit 'pause', e-stop is for emergencies. It should be used to keep from loosing a hand, or to keep the equipment from tearing itself apart. Pause is to stop in a restartable manner. The machine may have to finish a cut before it can pause, but using e-stop means you are willing to lose the piece or repair it if something is wrong. I hope that helps. ... Jack On Fri, Nov 7, 2014 at 3:35 PM, Joe Hildreth j...@threerivershospital.com wrote: Bruce, 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, Joe -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- ... Jack Whatever you do, work at it with all your heart... Colossians 3:23 Anyone who has never made a mistake, has never tried anything new. - Albert Einstein You don't manage people; you manage things. You lead people. - Admiral Grace Hopper, USN Tell me and I forget. Teach me and I remember. Involve me and I learn. - Ben Franklin -- ___ 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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Kirk, Great information. I am still reading it. I wonder though, if a brake could be used with my router along side the PID. You gave me some great info to chew on. Thanks again. Joe - On Nov 7, 2014, at 4:05 PM, Kirk Wallace kwall...@wallacecompany.com wrote: While following this thread, I found these links: http://madpenguin.ca/blog/2012/02/16/an-emergency-stop-circuit-with-emc2/ the above has a brocken link to here: http://www.hs-compliance.com/uploaded/documents/THE%20EMERGENCY%20STOP%20-%202012%20ver%202.0.pdf For spindles, Warner makes a magnetic release brake which brakes when power is cut: http://www.altraliterature.com/pdfs/FB%20Series-Permanent%20Magnet%20Brakes.pdf These fail to a safe condition. eBay can be a good source. A little less fail-safe is braking an AC motor with a DC current: http://www.homemetalshopclub.org/news/sep01/sep01.html http://www.electrical4u.com/induction-motor-braking/ There should be a version for router motors. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/ -- ___ 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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Bruce, Thanks for the information. You gave me quite a bit to chew on. Having a computer and electronic background I tend to think of logic being implemented via discreetly or through a micro-controller. I never really thought about relay logic. I have never tried to implement a logic circuit with relays, so would have to look at some samples. Off the top of my head it would seem that driving coils in series would be an AND and the same coils in parallel would be an OR. But beyond that no clue really. You said I shouldn't use IC to implement logic, but aside from the Y and !Y (NO and NC contacts) output logic why do you recommend against it? Currently, I have 5Vdc, 36Vdc and 110Vac that I am dealing with. Seeing that the 5Vdc power supply supplies my BOB, and other future devices, TTL logic just seemed natural. I agree with you about the software E-Stop versus the Hard E-Stops. I will insist to my Boys and wife that if SHTF, ALWAY hit the big red buttons! Thanks again for all the support, advice, direction and resources. I appreciate it. I see I have a little reading on the subject to catch up on. Regards, Joe - On Nov 7, 2014, at 4:34 PM, Bruce Layne linux...@thinkingdevices.com 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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
On Friday 07 November 2014 18:58:19 Joe Hildreth did opine And Gene did reply: Bruce, Thanks for the information. You gave me quite a bit to chew on. Having a computer and electronic background I tend to think of logic being implemented via discreetly or through a micro-controller. I never really thought about relay logic. I have never tried to implement a logic circuit with relays, so would have to look at some samples. Off the top of my head it would seem that driving coils in series would be an AND and the same coils in parallel would be an OR. But beyond that no clue really. You said I shouldn't use IC to implement logic, but aside from the Y and !Y (NO and NC contacts) output logic why do you recommend against it? Currently, I have 5Vdc, 36Vdc and 110Vac that I am dealing with. Seeing that the 5Vdc power supply supplies my BOB, and other future devices, TTL logic just seemed natural. I agree with you about the software E-Stop versus the Hard E-Stops. I will insist to my Boys and wife that if SHTF, ALWAY hit the big red buttons! Thanks again for all the support, advice, direction and resources. I appreciate it. I see I have a little reading on the subject to catch up on. Regards, Joe Joe; One thing I would think needs stressed, is when doing the relay logic stuff, it should all be dependent on an energized relay, so that if a power bump comes along, even a 50 millisecond one, all relays should de- energize and stay that way so there is protection when the power comes back up. Having the machine, with a slowing or stopped spindle, suddenly get jerked 1/4 sideways, probably snapping off a $20+ dollar solid carbide mill, or chewing on your hand if you reach for it, isn't something you want to happen. Using power to hold the relays closed when its in normal operation is a relatively small cost for that sort of safety. Some would call it sensible too. ;-) - On Nov 7, 2014, at 4:34 PM, Bruce Layne linux...@thinkingdevices.com 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
Re: [Emc-users] A beginners question about E-Stop and Charge Pumps
Joe, In the words of Roseanne Rosannadanna, you ask a lot of questions! :-) You don't wire the coils of relays in series for relay logic. The coil voltage is selected to match the voltage you want to use to activate it... 5VDC, 12VDC, 24VDC, 120VAC, etc. You wire the relay contacts in series to implement an AND function (as is the case with your E-stop switches and a relay that mirrors the status of the internal LinuxCNC E-stop signal, and any other relay controlled signal you want to generate an E-stop). You'd wire the contacts from different relays in parallel to implement an OR function. The reason I suggested using relay logic for this application is simplicity. You'll need a relay to externalize the internal E-stop status anyway, so just wire the contacts in series with any E-stop switches you have and you're finished. Why add any discrete logic ICs to that? It's needless complexity. I'm generally a big fan of implementing logic in software or firmware. I've replaced a lot of goofy 1950s technology relay logic where relays and electromechanical timers were used in the 1990s because someone didn't know how to use a PLC or (my favorite) a one dollar RISC microcontroller. But if you already have the relay and that's all you need, why add an Arduino to drive the relay? If you search for E-stop circuit and look at the images, you'll see lots of examples and it'll make sense. There are also some standard circuits for input power disconnects (I don't go to that formality for my small CNC machines) with fuses/breakers, ON and OFF pushbutton switches that latch the ON condition until the OFF button is pressed, etc. Bruce On 11/07/2014 06:58 PM, Joe Hildreth wrote: Bruce, Thanks for the information. You gave me quite a bit to chew on. Having a computer and electronic background I tend to think of logic being implemented via discreetly or through a micro-controller. I never really thought about relay logic. I have never tried to implement a logic circuit with relays, so would have to look at some samples. Off the top of my head it would seem that driving coils in series would be an AND and the same coils in parallel would be an OR. But beyond that no clue really. You said I shouldn't use IC to implement logic, but aside from the Y and !Y (NO and NC contacts) output logic why do you recommend against it? Currently, I have 5Vdc, 36Vdc and 110Vac that I am dealing with. Seeing that the 5Vdc power supply supplies my BOB, and other future devices, TTL logic just seemed natural. I agree with you about the software E-Stop versus the Hard E-Stops. I will insist to my Boys and wife that if SHTF, ALWAY hit the big red buttons! Thanks again for all the support, advice, direction and resources. I appreciate it. I see I have a little reading on the subject to catch up on. Regards, Joe -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
