I am running a cnc'd jet 9x20 lathe with a treadmill motor and dc motor controller with a 5k pot for speed control in manual.
I previously was running the speed controlled from LCNC from the parport to an opto interupter for isolation from the motor controller which worked fine. I was running Gecko 320's with direct connection to the parport cable (no breakout board). Everything worked as advertised but a little slow due to latency issues. I recently upgraded to mesa 5i25/7i78 and have worked out all the problems (mostly created by myself). ...Except for one: I am using the 7i78's isolated pwm to analog output for speed control and it works as advertised as well which means that the "wiper" voltage on pin 17 starts out at 10 volts when the speed command is 0 rpm and goes down to 0 volts when the speed command is at max. I know that the 7i78 manual warns that this will be the case and that the "pwm must be inverted" if I need the analog out to follow the speed command directly instead of inversely. Problem is that I can't figure out where or how to "invert the PWM". The only signal I seem to be able to access in hal is floating point rpm 0 to max (my max is 1200 rpm). So when I invert the signal the result is the mathmatical reciprocal of 1 to 1200 or 1 to .00083333. Of course when this gets to the motor controller the resulting output is 0 speed at all demands. How and where do I 'invert the pwm' Thanks, Cecil ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
