On 04/01/2017 19:00, Russell Gower wrote:
Hi,
Thanks for that, tit's basically the same config as mine except I was using
named instances, i've just tried doing it the same as below with numbered
components but it still behaves the same.
Can I ask what platform your running on (BBB or PC)?
It is from a PC using a parport interface, I don't use BBB
Python is a black art to me, but i’ve done some probing with hal meter, and
it’s the lowpass.0.out pin that is going to nan and then sticking so it looks
like an issue in the lowpass component - I’ll checkout the source code and have
a dig around the source code for that as I suspect it’s an platform related
issue (I’m running on an BBB).
Thanks
Russell
On 4 Jan 2017, at 09:14, [email protected] wrote:
For what it is worth, this is a snippet from my configs as to how I do the same
on my lathe (the other components are used elsewhere)
# **** Use ACTUAL spindle velocity from spindle encoder
# **** spindle-velocity is signed so we use absolute component to remove sign
# **** ACTUAL velocity is in RPS not RPM so we scale it.
addf scale.1 servo-thread
addf scale.2 servo-thread
addf abs.1 servo-thread
addf abs.2 servo-thread
loadrt lowpass count=1
addf lowpass.0 servo-thread
setp lowpass.0.gain 0.01
##########################################################################################
# Display spindle speed in pyvcp bar
##########################################################################################
setp scale.1.gain 60.0 #convert velocity per sec into rpm
net spindle-velocity => lowpass.0.in
net filtered-spindle-velocity <= lowpass.0.out => abs.1.in
net absolute-spindle-velocity <= abs.1.out => scale.1.in
net scaled-spindle-velocity <= scale.1.out => pyvcp.spindle-speed
I do not use spindle-at-speed.
It is an absolute pain unless you have a high mass spindle or an actual
physical encoder rather than just an index pulse from a pickup.
The fudge factor you have to program in to prevent program pauses due to speed
fluctuations, makes it irrelevant.
I just command a 4 second pause after M3, which is enough to get to speed and
stabilise on my machine.
regards
On 04/01/17 08:48, Russell Gower wrote:
Hi Marius,
The examples in the documentation (all be it the upstream documentation, but
I didn’t think we would have diverged much in this area) had it at 0.01 as do
all the example configs i’ve found whilst googling - I have also tried setting
it to 1.0 which had the same out come.
Regards
Russell
On 4 Jan 2017, at 06:31, Marius Alksnys <[email protected]> wrote:
Isn't your lowpass gain higher than 1 ?
01/03/2017 09:31 PM, Russell Gower rašė:
Hi,
I wonder if someone could help me diagnose an issue I have with trying
to use a low pass filter to stabilise the pyvcp spindle speed display in
Axis, I got the idea from
here http://linuxcnc.org/docs/html/examples/spindle.html
With the low pass filter in place the speed is displayed for a few
seconds then goes to “nan” and the following is output on the terminal I
launched machinekit from
Exception in Tkinter callback
Traceback (most recent call last):
File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1437, in __call__
return self.func(*args)
File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 498, in callit
func(*args)
File "/usr/lib/python2.7/dist-packages/vcpparse.py", line 154, in updater
a.update(pycomp)
File "/usr/lib/python2.7/dist-packages/pyvcp_widgets.py", line 1219,
in update
end, self.bh-1)
File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 2205, in coords
self.tk.call((self._w, 'coords') + args)))
ValueError: could not convert string to float: floating
If I remove the lowpass filter then the speed is displayed fine (apart
from the jitter).
My config files can be found here
https://github.com/russellgower/Lathe-Config.git
Thanks
Russell
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