2013/6/9 Florian Rist <[email protected]<https://mail.google.com/mail/u/0/?view=cm&fs=1&tf=1&[email protected]> >
> Hi Andrew > > Hi Florian, > > It depends on when you need the brakes on. > > Well, the brakes are supposed to prevent the servo from moving when > powered off, for safety reasons but also to be able to power up the > machine without the need to home the axis (nor sure if this is really > possible) > > The simple solution is connect brakes to enable. > > So I take the enable signal for the servo controller (7i39) and use that > to switch on the brae supply, right? > > I guess so. I usually use relay modules like this http://www.ebay.com/itm/251267628031 for that purpose. > > > Other is powering brakes when commanded velocity magnitude > > exceeds some near-zero value. > > sounds more elegant, but that means I have to use an extra i/o pin (no > problem there are plenty of them free) and generate the signal for it > (don't know how to do so, right now) > Yes. I would use abs to get absolute value of velocity and then comp to compare it to say 0.1 or 0.01 (slow enough but not zero). http://www.linuxcnc.org/docs/html/man/man9/abs.9.html http://www.linuxcnc.org/docs/html/man/man9/comp.9.html The question is which signal to use for velocity input: axis.N.joint-vel-cmd (or probably PID outputs) for each axis with 3 independent brakes, or motion.current-vel for common brake signal. Something like this. We can continue with details if nesessary. Andrew ------------------------------------------------------------------------------ How ServiceNow helps IT people transform IT departments: 1. A cloud service to automate IT design, transition and operations 2. Dashboards that offer high-level views of enterprise services 3. A single system of record for all IT processes http://p.sf.net/sfu/servicenow-d2d-j _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
