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? 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) 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
