On Thu, 2011-05-12 at 11:20 -0500, Jon Elson wrote: > dave wrote: > > > > How serious is the problem of using the battery, i.e. what is the > > expected life of the battery? Is the a real maintenance problem? > > Of course, the next question is accessibility to replace the battery and > > the cost. > > > > How do Fanuc people deal with this in the field? > > > Fanuc recommends replacing the 4 alkaline cells (I'm guessing AA size) > every year, while the machine is powered on. > What has me worried is the battery only backs up the position count in a > memory chip, it doesn't power the encoder. So, if the machine is bumped > while control power is off, the alignment would be wrong. I'm not sure, > it may correct itself the next time it passes the index position, but > there would then be a discontinuity in position at that moment, likely > to cause a servo following error. > > Also, they have this procedure for indexing the encoder any time the > power has been lost (swap motors, replace cables, etc.) You release the > brakes (if any) and manually crank the machine to be close to the home > position, power the encoder on and then crank it past the home index > position. This sets the revolution count to zero over your home position. > If I could get this type of encoder to work with the way EMC2 does > homing, I'd feel a lot more comfortable with it. > > A couple months ago I could have gotten a motor with the serial encoder > for under $100 on eBay, now it looks like they are all over several > hundred $, even the broken ones. Well, I can keep this loaner for a while. > > Jon Yep! Ebay is unpredictable. Sometimes this is good; other times not. What are you using for electronics to examine the encoder output?
I keep thinking about an encoder with that resolution directly on the shaft of an indexer or even an A, B or C axis. Then again, maybe 10K counts/rev is good enough, using my usual 2500 ppr Koyo encoders. On my machines the computer is powered by 120V single phase and is independent of the 3 phase used for spindle, servo drives, etc. The computer is powered up all the time so any movement is tracked. Don't know if this is practical for everyone. Dave > > ------------------------------------------------------------------------------ > Achieve unprecedented app performance and reliability > What every C/C++ and Fortran developer should know. > Learn how Intel has extended the reach of its next-generation tools > to help boost performance applications - inlcuding clusters. > http://p.sf.net/sfu/intel-dev2devmay > _______________________________________________ > Emc-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ Achieve unprecedented app performance and reliability What every C/C++ and Fortran developer should know. Learn how Intel has extended the reach of its next-generation tools to help boost performance applications - inlcuding clusters. http://p.sf.net/sfu/intel-dev2devmay _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
