Eric H. Johnson wrote: > Peter, > > Thanks. That is basically what I thought. It has been reported to me that, > in a servo / encoder system, if EMC is shut down, then one or more axes are > moved and finally EMC is restarted, upon clearing the e-stop a runaway > condition occurs (at least sometimes). I have to get more information, but I > thought perhaps the Mesa board was holding onto the position information > while EMC was not running, and then once the e-stop is cleared, tries to > move to the initial position (i.e. 0,0,0). > > At least with my boards, every time you E-stop or use F2 to go to "Machine Off" then the commanded position tracks actual position. Then, when you use the F2 key to go to "Machine On", the commanded position starts from where the machine is. So, there is no sudden jump to the last position. If I have a huge following error limit set, and power down the servo amps (without tripping an E-stop condition) then move the motor and power the servo back up, then I will get a jump. But, that is the only way I know to cause that scenario. I know that the PPMC driver does zero out the encoder counters when it is started. Also, the counters are zeroed when the axis is homed, at least if you have home to index turned on in the ini file.
Results with the Mesa boards "should" be similar, but there could be differences in driver behavior. Jon ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
