#linuxcnc-devel Logs

Jul 02 2021

01:55 PM Roguish_desk: pcw_home, morning Peter. wierd problem here with my vfd and the spinx1 board. the spinx1 voltage out keeps going to 10.58 when I max the desired motor speed at 5000. the output_scale=5000, max_output=5000. what's up?
02:00 PM Roguish_desk: shouldn't the voltage top out at 10.0???
02:08 PM Roguish_desk: the voltage goes up linearly, and hits 10.0 at 4425 rpm, not 5000
02:12 PM Roguish_desk: the vfd is set to max at 10.0 volt input, so the actual motor rpm tops out at the value it is at 10.0 volts.
02:13 PM Roguish_desk: no PID at this time
02:20 PM pcw_home: The SPINX1 output will go to full scale at 100% PWM so if the VFD outputs 10.58V that is what you will get at 100%
02:21 PM pcw_home: so if the VFD RPM is 5000 at 10V, you could set the scale to 5290 so you get 10 at a commended 5000 RPM speed
02:22 PM Roguish_desk: i don't follow. is the spinx1 not quite linear?
02:23 PM JT-Shop: is 100% PWM == to reference voltage?
02:31 PM Roguish_desk: pcw_home, is there a problem in the spinx1 dac? i assume there is a dac...
02:31 PM Roguish_desk: JT-Shop, question to me or pcw?
02:31 PM JT-Shop: peter
02:31 PM Roguish_desk: pcw_home, i'll try it right now. easy to setp the scale.
02:31 PM JT-Shop: I'm thinking 100% pwm is the same voltage as SP+
02:34 PM Roguish_desk: pcw_home, no go. i set the max_scale to 5290. lowered the output voltage, but still overshot. and went to 10.58. hit 10.0 at a lower commanded rpm
02:34 PM Roguish_desk: i'll set the scale higher....
02:36 PM Roguish_desk: scale = 5500 too high. coming down
02:44 PM Roguish_desk: JT-Shop, yes, i believe that is the intent.
02:48 PM Roguish_desk: pcw_home, that's not really a good solution. i see the problem that it's starts out too high. scale=5250 give 10.01v t 5000, but 2.45v 2000rpm not 2.0v. the base voltage is too high.
04:29 PM Roguish_desk: pcw_home, hello..... i'm using the VFD 10v ps to feed the spinx1 board. just measured the 10v as 10.71v. would that through the spinx1 board off? should i use an external 10v ps?
05:14 PM -!- #linuxcnc-devel mode set to +v by ChanServ
09:34 PM pcw_home: Roguish_desk: (should you look later) the 2.45V when you expect 2.00V is due to non-linearity
09:35 PM pcw_home: in the SPINX1 probably because the PWM rate is too high. Setting the scale shout compensate correctly
09:36 PM pcw_home: for the fact that you dont have exactly 10V
09:37 PM pcw_home: SPINX1 nominal PWM rate is 5 KHz