On Thursday 06 November 2014 16:29:22 Billy Huddleston did opine And Gene did reply: > Hey guys, > > 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? > > Do you configure it as a step/dir like a stepper setup and somehow read > the encoder info in? Or do you configure it as a velocity setup like > you would when you configure a servo using +-10V Analog control? > > In the case of velocity control, would you have to tune PID and how > would that effect the driver which is really expecting it to be a > step/dir pulse train.. I.E so many steps = this position. > > Thanks, Billy
I don't know the exact details for any of those questions. My mill is setup with straight, software driven steppers. Considering the motor voltage could be called a bit low at 28 volts, it does do what I tell it to do within the speed and accel limits that motor voltage imposes. But a mesa 5i25 card came my way when I last rebuilt my lathe, which is also triple stack nema 23 steppers, but with around 38 volts & change. When I first ran pncconf, to get a basic set of files, I was somewhat amazed to see that even though I was using steppers, the configs generated made use of 3 PID modules, one for the motor and 2 for the axis's of the lathe. I assume that somehow the 5i25 lashup is sending the steps issued back to the PID controller, because as long as I don't crash it & make a motor slip, it Just Works(TM), and generally works very well as long as I stay within the speed limits imposed by the motor voltage. Z for instance can march to either end of the bed at 60 ipm, which is about 4x faster than the mill can move. Which are you trying to setup, a mill or a lathe? Does it have a variable speed, reversible spindle motor? Does it have an encoder on the spindle? Are you using the parport direct, or have you a card, similar to the Mesa 5i25? If the answer to all of those is yes, my configs and hal files might be a starting point Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
