On 5/23/2012 3:29 PM, John Kasunich wrote: > > On Wed, May 23, 2012, at 12:13 PM, Jon Elson wrote: >> andy pugh wrote: >>> On 23 May 2012 07:08, Jeshua Lacock<jes...@3dtopo.com> wrote: >>>> I am guessing there is not an easy way to detect this condition, >>> It should be possible to check if your PID is saturated for more than >>> a second or so. >>> >> But, this still doesn't detect a servo runaway when the Gecko drive >> is started up. LinuxCNC is not sending any command to the drive at >> this point. So, before F2 is pressed, PID output is clamped at zero. > I guess I must have missed something. I never saw him say he was using > drives with step/dir inputs. If that is the case, then he probably > isn't > using PID loops at all - the drives are closing the position loop and > LinuxCNC is treating them like steppers. > > I automatically assumed that servo meant servo - a PID loop in EMC, > driving either an analog output (DAC or PWM) to a drive, or direct > PWM output to a power stage. In that scenario, there are multiple > ways to address the problem. But if the loop is being closed in the > drive, then it is really just a glorified stepper machine, and > LinuxCNC can't do a damn thing to help. >
Of course all roads lead to LinuxCNC, but is there some reason one couldn't/wouldn't start with one of the many microcontroller chips or even ARM-based SoCs and build a separate watchdog for the purpose of detecting and stopping servo runaway in its tracks? It would seem to me almost any has more than enough capability to do so. Just color me curious... Regards, Kent ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
