On Sat, 26 Dec 2020 at 10:00, andrew beck <[email protected]> wrote:
> also what do people do for E stop circuits with analog systems? I have only > used a step direction system before this On my lathe the main servo power supply comes via a contactor with a 24V coil, and that coil power passes through two e-stop switches. LinuxCNC controls the 24V contactor coil, but the e-stop switches in series in that circuit can over-ride. I couldn't remember if the contactor was controlled via an ssr, or whether it's directly from a 7i84 output. So I found this photo: https://photos.app.goo.gl/7VSURFqEFVq9s3bk8 which suggests an SSR for the main relay. There is a wire back from the 24V coil terminals to a 7i84 input. That is used to inform LinuxCNC if the e-stops are activated, triggering the software e-stop and turning the machine off. I seem to recall making sure that there was a protection diode, so that the voltage as the coil turned off didn't damage the 7i84 input pin. So, e-stop drops out the contactor, the drives turn off, LinuxCNC spots that the coil is de-energised and e-stops itself to match. -- 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
