> Date: Mon, 6 Jan 2014 10:29:55 +0000 > From: andy pugh <bodge...@gmail.com> > Subject: Re: [Emc-users] Ramped feed rate, unlurking... And new > request for assistance > To: "Enhanced Machine Controller (EMC)" > <emc-users@lists.sourceforge.net> > Message-ID: > <can1+yzxnhvl1bppekzzxmlcdwqozrbykvx-pvjk7zbd5_0b...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > On 6 January 2014 03:54, Andy <a...@evanspt.com> wrote: > >> however I've been wondering how I could tie the feed rate to the motor >> load. I'll try to get my head around this as I move forward on my project. > If you can find a way to get motor current data from the spindle drive > into HAL then LinuxCNC has adaptive feed capability built-in. > The difficulty here is that there isn't a huge range of analogue-input > hardware for LinuxCNC. > What are you using to generate the step pulses? Andy, pardon my ignorance, what /would/ be generating the pulses? The PC is a Gigabyte E350N mini_ITX feeding a break-out board. >> http://www.automationtechnologiesinc.com/wp-content/uploads/downloads/2012/06/KL-8082H.pdf > That says 10uS step length and 200kHz. Which doesn't add up really. > (200 kHz is 5uS combined step + dir) > direction setup is quoted as 5uS, though if it was my machine I think > I would be tempted to configure it in CC/CCW mode rather than > step/dir. Hmm. Had not ever considered that, trying to understand implications now... What is your thinking?
The machine seems to be working when I use 10ns for step and 5ns for direction. I am just not completely comfortable without knowing those values are optimum. In the interim I will push on with those values. Is there any safety to be had by doubling those? The reply to my questions with the supplier, Automation Technologies, do not provide useful information. I hope I am not being unfair to this vendor, but my impression is that he does not want to be bothered by Linux users. > These drivers are supposed handle the encoder feedback and do any > necessary travel corrections. As I understand, LinuxCNC has the > capability to use the encoders, so maybe I would be better off with > Geckos and wiring the encoders back to EMC2? > LinuxCNC can handle the encoders, but only at quite low count rates > unless you add extra hardware. Parallel-port counting tops out at > about 20kHz, which with a high-count encoder can be rather a low motor > speed. > > You can view the drive/motor combination as a conventional stepper > drive, except one that can detect stalls and that will never > (mechanically) miss a step rather than a servo system. Agreed, that is how I see it. In its application, I am not really asking much of this system. At most, I am moving two axes at once, and no blazing speeds. I just want it to be reliable. It is extremely rare that my existing open-loop system has an issue, but I went this direction for assurances that I wouldn't ever miss/lose steps. I had thought that even an error with stoppage (rather than a dynamic correction) would suffice. Thanks for the information! ------------------------------------------------------------------------------ CenturyLink Cloud: The Leader in Enterprise Cloud Services. Learn Why More Businesses Are Choosing CenturyLink Cloud For Critical Workloads, Development Environments & Everything In Between. Get a Quote or Start a Free Trial Today. http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
