I use Step/Dir servo controllers with a 5i25 configured to use stepgens. The encoder feedback run back to linuxcnc. Linuxcnc watches for following error and faults if it gets out of hand. My results have been great so far. It's a bit of a pain to load up tuner software to tune the drivers separately but once that is done it has worked well.
I would imagine that even if you did the velocity thing, the servo driver would still be using its own PID loop, thus just greater complexity overall. If you could bypass the PID loop in the driver and it would just become a dumb amplifier, the velocity approach would be worth it, because linuxcnc is easier to tune and gives you greater control. On Thu, Nov 6, 2014 at 5:46 PM, andy pugh <[email protected]> wrote: > On 6 November 2014 21:29, Billy Huddleston <[email protected]> wrote: > > > Was looking into using a Step/Dir servo solution. It's possible to send > the encoder info back to linuxcnc to complete the control loop to > linuxcnc. My question is, how do you > > configure Linux CNC in this case? > > There are two ways. You can just configure exactly like a stepper, > then either only use the encoder feedback to detect following errors, > or in fact use an error output from the drives to detect that. > > The alternative is to configure the stepgens in velocity mode, which > means that they output a step and direction signal at the _rate_ > requested, not the number of steps requested. This means that the > step-pulses are a digitally encoded velocity signal. (conceptually > identical to +/- 10V velocity command). The drive remains configured > just the same, but the HAL config is a lot more servo-like, with PID > components (that need tuning) and encoder feedback. > > I have never used either setup, so can't comment on the pros and cons. > > You might also want to consider the (rather cheaper) hybrid steppers > that have recently appeared. > > http://www.leadshine.com/producttypes.aspx?type=products&category=easy-servo-products&producttype=easy-servo-drives > > Available on eBay. > > -- > atp > If you can't fix it, you don't own it. > http://www.ifixit.com/Manifesto > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
