Thanks everyone. Long winded reply below. The commercial world, I believe, includes electrical standards that require all power to be removed with an ESTOP. That changed as PCs became the controllers and ESTOP no longer had to remove power from PCs like they would have from PLCs. But certainly anything that could move and hurt someone fell under that envelope. Standard may vary in different countries.
I had the Gecko Stepper drive fail due to burnt traces on the inner layers that heated and then melted the connector. Possibly due to excess moisture and some sort of growth across the pins. The failure happened to the Z axis drive during a knee move downward while milling. The subsequent XY move expecting the tool bit to be out of the cavity broke the tool and mucked up the work. The open loop stepper had no idea that it wasn't working anymore. When I've inadvertently run one of the XY DC servos (HP_UHU) into something that results in a following error the fault open collector output pulls down the enable signal on the other drives (STMBL and the HP_UHU). The Bergerda Spindle drive and now knee Bergerda drive are now also wired into that enable signal. If I move the Knee and disconnect the encoder from the STMBL the knee stops as it should. My ESTOP is outside all that. The ESTOP buttons are in series with the main system Motor Power contactor and removes AC power going to the DC power supply running the DC Servos and the STMBL 4th axis. That AC is also fed to the Bergerda drives running the spindle and the knee motor. My theory in both approaches is that since I don't have closed loop control of the encoders through the PC (or at least I'm not tracking the encoders with existing hardware) that a single fault from say the STMBL that faults the HP_UHU DC servos automatically results in a loss of position. The HP_UHU recovery is not just a removal of the fault but a reset of the processor. There is no other way out with them. The Bergerda reset the fault once the enable is disabled and re-enabled. Assuming the fault is cleared. Unplug the encoder and it will stay in fault. Gene also mentioned start up surge for the DC power supplies for his system. My 105VDC supply running the DC Servos and HP_UHU is also brought up softly. That delay doesn't affect the HP_UHU drives because their 15V logic circuit is powered from the instrument power supply which remains connected during an ESTOP. But the STMBL introduced a new problem. It may well have the 24V stable instrument power but it faults on low motor voltage. And the low motor voltage is there as the DC supply is brought up. So the STMBL faults. Which shuts off the DC motor power. Click on the LinuxCNC Power button and up comes the DC motor power, the drive enable and the STMBL faults because DC isn't there yet but enable is. Dog chasing the tail. So now on power up the Enable signal is blocked by a DC power ready signal and a 1/2 second delay after that. Now the STMBL doesn't fault. So back to the original subject. It's not just motion that can cause a driver fault. A broken encoder wire, DC or AC power instability, or even random electrical noise. In all those cases I've found I still have to execute a HOME ALL command to bring things back. With repeatable home switches the G54 still takes the system back to where it was and as long as the replacement tool (or whatever) is still in the same place, even after a power loss, machining can continue. But thanks again for the feedback. John > -----Original Message----- > From: andy pugh [mailto:bodge...@gmail.com] > Sent: February-10-21 8:30 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Dealing with Servo Faults > > On Wed, 10 Feb 2021 at 16:26, Jon Elson <el...@pico-systems.com> wrote: > > > > So, non-faulted drives will stop, but hold position. > > > > > Well, the issue there is whether a faulty drive would > > actually stop when disabled. > > I was assuming that the faulted drives would disable themselves. I was > thinking about what to do with the drives that have not faulted. > > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > � George Fitch, Atlanta Constitution Newspaper, 1912 > > > _______________________________________________ > 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
