2012/5/30 andy pugh <bodge...@gmail.com>: > On 30 May 2012 03:42, Jon Elson <el...@pico-systems.com> wrote: > >> When the home command is given, both motors are given >> identical step >> rates toward the home position. When the first motor trips the home >> switch, the >> step pulses are interrupted to that motor. > > I think that one would have to do more than simply interrupt the > steps, as that would cause the motor to slip to an unknown position > (with steppers, not so with step/dir servo amps)
And why would it do so? For example (syntax not correct, just demonstrating the principle), with mux2bit component (I made this up for my last machine - standard mux2 customized for bit inputs and output): net x-step-in mux2bit.in0 <-- stepgen.0.step setp mux2bit.in1 false net x-step-out mux2bit.in0 --> parport.0.pin-01 net x-interrupt mux2bit.sel <-- [whatever HAL signal to command that] There are 2 options, depending on mux2bit.sel pin - either the stepper drive receives the step signals or that lpt pin is set to be false. And if stepper drive does not receive step signals, it will hold its position (in the place, where it was, when step signal was interrupted), not randomly drift somewhere. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ 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
