On Saturday 18 January 2020 15:07:35 John Dammeyer wrote: > Hi Gene, > > I've run into similar problems with my system as I try and make it > intrinsically safe. The issues I've run into involve the various > levels of intelligence in the hardware. I don't know if your 7i76 can > solve your problem since I'm not familiar with it. > > As I've said before I'm using the PMDX-126 Break Out Board which was > really more designed around MACH3 than LinuxCNC. Obvious because the > two ribbon cable connections and 4 mounting holes are designed to hold > the Smooth Stepper. (USB or Ethernet). Still haven't connected second > port on the MESA 7i92. But that's a different story. > > One of the 'features' of this BoB is the Charge Pump input. MACH3 can > generate this on any parallel port pin with a checkbox and can even > keep it running during the ESTOP IN (Pin 10 normally) by checking a > box in the main config screen. > > Under Linux CNC this is generated with stepper driver #4 > net machine-is-enabled => hm2_7i92.0.stepgen.04.enable > > The BoB, when configured to use a charge pump shuts off all outputs > when the charge pump vanishes. This includes the machine enable > signal (Pin 1). Under Linux this is: setp > hm2_7i92.0.gpio.000.is_output true > net machine-is-enabled => hm2_7i92.0.gpio.000.out > > Since the BoB has a couple of relays, one of them (SPDT) normally > allocated to motor direction or coolant, uses the NO contacts to be in > series with the ESTOP switch on the machine and feeds into the ESTOP > input (Pin10) on th BoB. If the Charge Pump vanishes, the BoB itself > takes care of shutting off the outputs which is like mechanically > hitting the ESTOP. > > Same with the limit switches. A FAULT (or NC ESTOP opening) input > into the BoB also causes all outputs to shut off. A small micro > removes that FAULT 4 seconds later but the system ENABLE (controlled > with the F2 power button) remains off after this. AC/DC power is > returned to the motors and the system. > > The problem I ran into was the FAULT or ERROR output from the various > motor drivers. A missing power supply voltage caused a fault on the > STMBL AC Servo drive. Something wrong on the DC HP_UHU servo drives > causes a FAULT. In all cases that shuts OFF High Voltage power and > then ON again. To reset the STMBL I have to bring the ENABLE FALSE > and TRUE. That's Pin 1 and done with the F2 button on the user > display. > > The HP_UHU drives were more problematic. They don't have an enable. > To clear a fault you either cycle 16V low voltage power or bring the > processor reset pin low. I did that with the NOT ENABLE signal and a > couple of opto coupler open collector transistors. Now when not > enabled the DC Servo drives are held in reset. And it's true, HV DC > and a shorted transitor driver pair could keep the motor running open > loop so still not the safest. > > I first tried enabling the high voltage with the system enable. This > created a race condition for both drives. The STMBL was enabled but > High Voltage wasn't there yet so it created a fault which shut off the > HV. Circular problem. > > The HP_UHU drive, when reset is released, blips the FAULT which shut > off high voltage again resulting in ENABLE going false which again > held the drive in RESET. > > SO the issue is that just after a reset or HV DC power being restored > both the STMBL and the HP_UHU blip their fault line. That shuts off > the BOB which removes the HV. Then when the HOV is re-applied it > starts all over again. Vicious circle. Hence the 4 second delay > before power is restored but the enable is held off keeping all the > servo drives either reset or not enabled. > > Once the ENABLE is set true, the FAULT from the drives is blocked for > a few seconds to allow the random start up faults to fix themselves. > All done with a PIC12F609 8 pin processor. > > For real safety I need to add a latching relay circuit that requires a > manual energize button to latch it on. So anything that shuts off > the HV opens this relay. And a button must be used to relatch it. > The original mill hardware has that on the Spindle and Coolant > switches. An ESTOP requires both switches set back to OFF before the > released ESTOP restores power. > > So for your system, look at a charge pump as a method of resetting > hardware. Then a relay wired in such a way that you have to manually > close the latching circuit to lock that relay closed. An ESTOP or > missing charge pump or even Limit switch can remove power. All your > switch has to do is momentarily close this relay and a second pair of > contacts will hold it closed. Since the primary contacts on this CAN > be part of the ESTOP NC circuit a machine FAULT like a limit switch or > motor driver automatically causes a removal of voltages. And, like > untwisting the ESTOP switch, you need to press a physical ON button to > relatch power. > > Hope that makes sense. > John Dammeyer For you it does, but without going to a separate parport, and using it to control power to the interface box and resetting the 5i25 jumpers for remote power from the boxes own supply, its a chicken v egg problem.
IOW I can't use a signal that has to pass thru the interface, to control the power to the interface, And even then with logic power coming in from the 5i25, will that leakage prevent the full drainage to zero that is needed to fully recover the substrate scr someplace in the 7i76D. Thats not what happened this time as the 12 volts remained good, whereas on the 6040, the 12 volts was being crowbared by this not on the schematic scr, but this time it was not. Maybe Peter has conjured up a theory by now, but I've not. > > > -----Original Message----- > > From: Gene Heskett [mailto:ghesk...@shentel.net] > > Sent: January-18-20 10:39 AM > > To: Enhanced Machine Controller (EMC) > > Subject: [Emc-users] I'm back to a sseriel failure that can only be > > fixed with a full powerdown of the whole system. > > > > Greetings all; > > > > If then. While shaving the side of the BXA's foot, swarf built up on > > the top of the y axis home switch, and when I went to brush it off, > > some of it went below the switch and shorted the 12 volts to ground. > > Lit the swarf strands up like a light bulb, which I don't quite > > understand since the teeny little switcher supplying that 12 vols. > > Short circuit protected, it shuts down at 2.1 amps. The switch still > > has the 12 volts on it but I've removed it from its bolt down. I > > have not used the halmeter to see if its traceable, but without > > sserial, I doubt I can read it. > > > > All the power leds on the power supplies are at normal brightness > > and so are the leds on both the 7i76 and the SainSmart bob on the > > 5i25's p2. > > > > The GO704 and its interface is wired like Peter recommends, but > > apparently thats not good enough, without doing a full powerdown on > > the computer and the separately powered interface box. So I think I > > am going to have to concoct a method involving the actual unused > > parport to act as a master switch for the whole thing so I can do a > > powerdown reset on this interface combo by command from the > > computer. > > > > I can't believe I've blown the 7i76D, the available voltages just > > aren't there, but Peter also cannot duplicate this fail. But I have > > now encountered it on 2 separate builds. > > > > Has anyone else actually invented this particular wheel? 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
