Thanks Andy, > On 17 May 2018 at 23:25, John Dammeyer <[email protected]> wrote: > > > Have I got it right? The DB25-1 ENABLE signal is usually: > > a) active high or > > b) active low > > on LinuxCNC systems? > > From: andy pugh [mailto:[email protected]] > If you are using the parallel port then I think that active-high (as > in, high voltage = e-stop) because p-port pins float high if the wire > breaks. > (Though I think that pin 1 is hardware-inverted, just to complicate matters) >
Below is from the Xylotex HAL which is why it's active low and DB25-10 has a pull up resistor on it. # this pin is output on DB25-1 # it is also used to enable the LVC541 driver/receiver on the interface board net machine-on bb_gpio.p8.out-07 bb_gpio.p8.out-26 => halui.machine.is-on setp bb_gpio.p8.out-07.invert 1 I believe "halui.machine.is-on" represents the ENABLE button on the user interface? The physical pin out is inverted by the HAL. The ESTOP in agrees with what you wrote below about "iocontrol.0.emc-enable-in" # this input signal must be active LOW to allow the system to energize. # this should be fed through an NC STOP type switch from DB25-1 to DB25-10 net estop-in bb_gpio.p8.in-09 => iocontrol.0.emc-enable-in setp bb_gpio.p8.in-09.invert 1 Thanks for the reminder about the user space. I am wiring up my estop to physically remove power from any of the motor drives which includes the spindle using the existing estop circuit which controls the main contactor relay. My machine ESTOP switch also has a spare NC contact which I will use to signal LinuxCNC that ESTOP happened. The DB25-1 is high impendence with no pullup resistor which explains why the 30A relay on the PMDX-126 BoB doesn't turn ON when the ENABLE is off. It may be easiest to rework the Xylotex Cape to create an active high signal so I have proper access to the 30A relay on the BoB. Shame not to use it. Again, thanks for the feedback. John > If you are using a different IO system then I would imagine that the > same logic might lead to different conclusions. > > To get the behaviour I wanted, one of my machines has two switch > blocks on each E-stop switch, one to drop out the main contactor and > the other to signal to LinuxCNC that the e-stop is pressed. > > The other machine measures the relay coil voltage to indicate when > e-stop has been pressed. > > I haven't found a good description of e-stop strategies in the docs. > But then I have not read them end-to-end. > There are three HAL pins that work together, but that can be > configured according to the requirements of individual machines. > > iocontrol.0.user-enable-out (Bit, Out) FALSE when an internal estop > condition exists > iocontrol.0.user-request-enable (Bit, Out) TRUE when the user has > requested that estop be cleared > iocontrol.0.emc-enable-in (Bit, In) Should be driven FALSE when an > external estop condition exists. > > But these pins are part of iocontrol, so run in a userspace context so > can not be 100% relied upon. > > There is also a realtime pin, but one that is more rarely used > > motion.enable IN BIT If this bit is driven FALSE, motion stops, the > machine is placed in the "machine off" state, and a message is > displayed for the operator. For normal motion, drive this bit TRUE. > > But even though this is a realtime pin it is still software, so not > 100% to be relied upon for safety. > > -- > 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, 1916 > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
