Closed loop spindle

I installed the same hal code as above on a lathe, only modifying it to use encoder instead of the switch and the speed control work fine, the use of the index signal for threading also work fine (the starting point at least).
But, when switching feedrate to mm per row it does not add up at all, and also the thread does not make the right pitch,
if I divide it with 60 it will be almost correct but not exactly right.
For example when I set it like below:
M3 s500
G95
G1 g90 x0 f0.01
I get a feedrate of 300mm/min or 5mm/sek
So it seem like the feedrate get 0.01 mm/sek of s500.

Any idea what could be wrong?

Below is the modified HAL code that use a real encoder:
Here I use the encoder scale and should not Linuxcnc show and run the spindle at the wrong speed if the settings are not correct?
As it is now I just pass it through the scale component but still spindle-fb-rpm show the right speed even though the scale is 1.

#*******************
# SPINDLE S
#*******************

loadrt scale count=2

loadrt lowpass names=lowpass.spindle
loadrt abs names=abs.spindle

addf scale.1 servo-thread #spindle scale
addf lowpass.spindle servo-thread
addf abs.spindle servo-thread
addf pid.3.do-pid-calcs servo-thread

setp pid.3.Pgain [SPINDLE_9]P
setp pid.3.Igain [SPINDLE_9]I
setp pid.3.Dgain [SPINDLE_9]D
setp pid.3.bias [SPINDLE_9]BIAS
setp pid.3.FF0 [SPINDLE_9]FF0
setp pid.3.FF1 [SPINDLE_9]FF1
setp pid.3.FF2 [SPINDLE_9]FF2
setp pid.3.deadband [SPINDLE_9]DEADBAND
setp pid.3.maxoutput [SPINDLE_9]MAX_OUTPUT
setp pid.3.error-previous-target true
setp pid.3.maxerror 1000

net spindle-index-enable <=> pid.3.index-enable
net spindle-enable => pid.3.enable
net spindle-vel-cmd-rpm-abs => pid.3.command
#net spindle-vel-fb-rpm => pid.3.feedback
net spindle-fb-rpm-abs => pid.3.feedback
net spindle-output <= pid.3.output

# ---PWM Generator signals/setup---

setp hm2_[HOSTMOT2](BOARD).0.encoder.04.scale [SPINDLE_9]ENCODER_SCALE
setp hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout4-scalemax [SPINDLE_9]OUTPUT_SCALE
setp hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout4-minlim [SPINDLE_9]OUTPUT_MIN_LIMIT
setp hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout4-maxlim [SPINDLE_9]OUTPUT_MAX_LIMIT

net spindle-enable => hm2_[HOSTMOT2](BOARD).0.7i77.0.1.spinena

net spindle-output => hm2_[HOSTMOT2](BOARD).0.7i77.0.1.analogout4



# ---Encoder feedback signals/setup---

# encoder feedback
setp hm2_[HOSTMOT2](BOARD).0.encoder.04.counter-mode 1
setp hm2_[HOSTMOT2](BOARD).0.encoder.04.filter 1
setp hm2_[HOSTMOT2](BOARD).0.encoder.04.index-invert 0
setp hm2_[HOSTMOT2](BOARD).0.encoder.04.index-mask 0
setp hm2_[HOSTMOT2](BOARD).0.encoder.04.index-mask-invert 0



# connect the HAL encoder inputs to the real encoder.
net spindle_index_in <= hm2_[HOSTMOT2](BOARD).0.encoder.04.input-index

#net spindle_index_in => encoder.0.phase-A
#net spindle-phase-b encoder.0.phase-B
#net spindle_index_in => encoder.0.phase-Z



net spindle-revs <= hm2_[HOSTMOT2](BOARD).0.encoder.04.position
net spindle-vel-fb-rps <= hm2_[HOSTMOT2](BOARD).0.encoder.04.velocity
net spindle-index-enable <=> hm2_[HOSTMOT2](BOARD).0.encoder.04.index-enable

# ---setup spindle control signals---

net spindle-vel-cmd-rps <= motion.spindle-speed-out-rps
net spindle-vel-cmd-rps-abs <= motion.spindle-speed-out-rps-abs
net spindle-vel-cmd-rpm <= motion.spindle-speed-out
net spindle-vel-cmd-rpm-abs <= motion.spindle-speed-out-abs
net spindle-enable <= motion.spindle-on
net spindle-cw <= motion.spindle-forward
net spindle-ccw <= motion.spindle-reverse
net spindle-brake <= motion.spindle-brake
net spindle-revs => motion.spindle-revs
net spindle-at-speed => motion.spindle-at-speed
net spindle-vel-fb-rps => motion.spindle-speed-in
net spindle-index-enable <=> motion.spindle-index-enable

# ---Setup spindle at speed signals---

sets spindle-at-speed true

# Use ACTUAL spindle velocity from spindle encoder
# spindle-velocity bounces around so we filter it with lowpass
# spindle-velocity is signed so we use absolute component to remove sign
# ACTUAL velocity is in RPS not RPM so we scale it.

setp scale.1.gain 1
setp lowpass.spindle.gain 1.000000
net spindle-vel-fb-rps => scale.1.in
net spindle-fb-rpm scale.1.out => abs.spindle.in


net spindle-fb-rpm-abs abs.spindle.out => lowpass.spindle.in
net spindle-fb-rpm-abs-filtered lowpass.spindle.out

# --- SPINDLE-CCW ---
net spindle-ccw hm2_[HOSTMOT2](BOARD).0.7i77.0.0.output-03

# --- SPINDLE-CW ---
net spindle-cw hm2_[HOSTMOT2](BOARD).0.7i77.0.0.output-02

loadusr halmeter -s signal spindle-fb-rpm -g 800 100

This is the INI part

#********************
# Spindle
#********************
[SPINDLE_9]
P = 10
I = 0.3
D = 0
FF0 = 1.0
FF1 = 0.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 2000
ENCODER_SCALE = 20
OUTPUT_SCALE = 2000
OUTPUT_MIN_LIMIT = 0.0
OUTPUT_MAX_LIMIT = 2000.0

Ok thanks I will try some more

andypugh wrote:

....And to answer the actual question... (Sorry).
Yes, I would expect the spindle speed to be incorrect with a scale of 1.

(though an FF0 of 1 will give at least an approximation of the right speed until the PID does its thing)

I suggest you have a look with Halmeter at the PID command, feedback, error and output and see if you can figure out what is going awry.

Tried some more now and When the speed is set to 500 pid command is 500, pid error is about 5, feedback is 500

Spindle revs counted 60 times faster that it should so I added a scale of 0.01699 and now it counts 100 per minut when speed is 100rpm and the spindle feedback also show the right speed, but still when running in g95 x0.2 at 500rpm the speed is about 60 times as fast as it should, the scaling doesnt seem to do anything.

Hello
I dont know what more to check, the spindle is running at the right speed, motion.spindle-speed-in is correct and
motion.spindle-revs is counting at the right speed, is not that all that matters?