PnCConf axis motor/encoder max output w/pwm?
- greenbuggy
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01 May 2013 09:53 #33473
by greenbuggy
PnCConf axis motor/encoder max output w/pwm? was created by greenbuggy
It seems to me that a lot of the info in the users guide, hal manual and integrator manual is aimed towards people that are using a DAC on a mesa daughterboard like a 7i48 to create +/-10V signals to drive analog servo amps
Unfortunately my mill didn't have any servo amps when I got it and so I went with mesa 7i29's which are PWM servo amps
I'm curious what the "max output" in the PnCConf wizard means as it relates to setting up PWM drives output, or if it can be disregarded. As I'm doing PID tuning my servo seems sluggish I want to make sure that the default "10.00" value here doesn't somehow translate into 10%. Thanks for the help
Unfortunately my mill didn't have any servo amps when I got it and so I went with mesa 7i29's which are PWM servo amps
I'm curious what the "max output" in the PnCConf wizard means as it relates to setting up PWM drives output, or if it can be disregarded. As I'm doing PID tuning my servo seems sluggish I want to make sure that the default "10.00" value here doesn't somehow translate into 10%. Thanks for the help
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01 May 2013 10:38 - 01 May 2013 10:40 #33474
by PCW
Replied by PCW on topic PnCConf axis motor/encoder max output w/pwm?
Looking at a sample pncconf created HAL file you can see that MAX_OUTPUT sets the PID output limits and OUTPUT_SCALE sets the PWM scale. As I said before you want to set OUTPUT_SCALE to the machine units per second of the machine with full motor voltage and then set MAX_OUTPUT to 95% of this value. For example if the motor speed at full on (motor voltage=DC power supply voltage) is 240 IPM (4 IPS) I would set output scale to 4 and MAX_OUTPUT to 3.8. For the 7I29 I would also make sure the PWM frequency is 20 KHz
#*******************
# AXIS X
#*******************
setp pid.x.Pgain [AXIS_0]P
setp pid.x.Igain [AXIS_0]I
setp pid.x.Dgain [AXIS_0]D
setp pid.x.bias [AXIS_0]BIAS
setp pid.x.FF0 [AXIS_0]FF0
setp pid.x.FF1 [AXIS_0]FF1
setp pid.x.FF2 [AXIS_0]FF2
setp pid.x.deadband [AXIS_0]DEADBAND
setp pid.x.maxoutput [AXIS_0]MAX_OUTPUT <<<<
net x-index-enable <=> pid.x.index-enable
net x-enable => pid.x.enable
net x-output => pid.x.output
net x-pos-cmd => pid.x.command
net x-vel-fb => pid.x.command-deriv
net x-pos-fb => pid.x.feedback
# ---PWM Generator signals/setup---
setp hm2_5i20.0.pwmgen.00.output-type 1
setp hm2_5i20.0.pwmgen.00.scale [AXIS_0]OUTPUT_SCALE <<<<
net x-output => hm2_5i20.0.pwmgen.00.value
net x-pos-cmd axis.0.motor-pos-cmd
net x-enable axis.0.amp-enable-out => hm2_5i20.0.pwmgen.00.enable
Last edit: 01 May 2013 10:40 by PCW.
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20 Feb 2014 03:30 #43988
by LAIR82
Replied by LAIR82 on topic PnCConf axis motor/encoder max output w/pwm?
Hello Peter,
Does this hold true for an analog amplifier signal as well?
Thanks
Rick
Does this hold true for an analog amplifier signal as well?
Thanks
Rick
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20 Feb 2014 12:02 #43996
by PCW
Replied by PCW on topic PnCConf axis motor/encoder max output w/pwm?
For velocity drives, It does make sense for the OUTPUT_SCALE and PID max output to be set to the axis velocity with 10V
applied to the drive. This makes the PID values comparable between different systems and allows guessing good starting PID and FF1 numbers
applied to the drive. This makes the PID values comparable between different systems and allows guessing good starting PID and FF1 numbers
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