skunkworks: LM211! (or 311)
interesting - that guy that bored a spindle taper in this thread: http://www.practicalmachinist.com/vb/showthread.php?t=122416&highlight=spindle+runout
is probably the guy who I got my collet chucks from: http://www.maritool.com/
skunkworks: hmm, on further reading, its not clear if the LM311 works with inputs down around ground
heh - I may have to do some more research ;)
jmkasunich: this guy has your attitude about comparators http://www.cnczone.com/forums/showpost.php?p=480057&postcount=11
qoute.. The LM339 / LM393 will work because it IS a comparator.
"input common mode voltage includes ground" <-- LM339 datasheet
yes - I read that today.. ;)
its not as fast as a 211, but fast enough (damn sure faster than a TL084 opamp)
oh - whatever.. you comparator elitist!
did you see my question about the sense resister?
don't think so?
I was wondering how to handle the comparator side of it.. what is the best way to handle the logic side ground of the resistor.
where is your schematic again?
I think this is the latest incarnation. http://www.electronicsam.com/images/KandT/servostart/newschem4.png
you need two distinct gnd symbols
something like PGND for power ground
that is what I was wondering - if I should officially separate the power gnd from the logic grnd
use PGND for the main power supply connection, one of the sense resistor ground leads, and the main bus capacitor (I don't see that on your schematic)
it isn't there.. it was just 2 of the pads.
use GND for everything eise - including the ground of the 7812
I have not started modifying the schematic yet.
* I have not started modifying the pcb layout yet.
actually, since you only have one GND symbol on the power side, you don't really need another symbol
just delete that GND (the one connected to the bottom right resistor terminal)
so - the only connection between logic ground and power gnd is going to be the logic side leg of the sense resistor?
PAD4 can be the power ground (add another PAD for the cap ground)
now I need to find some comparators.
I bet digikey sells them every day..
"comparators - 3114 items"
wow, $1.15 for 339s (quad)
I'm spoiled - I see work's pricing, we buy in volume
I think a 339 is well under a quarder
this 339 is only $0.45 qty 1 and goes down to 11 cents qty 5000 .. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-1393-5-ND
speaking of which, what kind of technology does a digital logic analyzer use when you select different I/O standards? does it set a reference voltage and use a (very fast) comparator? or does it use some other approach (analog switches to actual logic of whatever kind?)?
I suspect the former
duh on the 339 - silly /me searched for "comparator", then filtered by manuf for National Semiconductor
TI pricing much better
digikey doesn't let you filter comparators on speed
or sort on price (my pet peeve)
was the logic analyzer question just out of curiosity, or are you thinking of building one?
[02:49:00] <jepler> http://emergent.unpy.net/01216696167
wondering what a proper input stage would be like for this fpga-based one that I bought
I'd definitely use the DAC setting reference for damn fast comparator approach
oh, and that reminds me, I saw something rather odd when I was first messing with the scope
as you can see, I'm scoping a simple binary counter -- it's generated by an avr, and there are actually two low-order bits that I'm not probing there
the first version of the fpga firmware didn't have pull-ups or pull-downs, so most of the inputs (26 of 32) were just floating. most of them would stick at a particular value, some of them would wander around
(later, I added pull-ups in the fpga design and all that stopped)
but before I did that, I saw something weird: in the next channel, the first unused ones, I got edges in a particular pattern: several transitions before the slowest signal would change state, I would get a bunch of rapid transitions on the unused line
much longer than the 2-instruction pipeline on the avr, for instance
it seemed like that floating line was anticipating the future
I wish I'd saved a screenshot of it
"several transitions" ?
meaning several counter LSB counts? or several analyzer samples (at what rate?)
several LSB counts
many many analyzer samples -- probably 20MHz or 50MHz
so many many microsconds
several microseconds at least
that rules out any kind of crosstalk
jepler, I have a manual for a tek p6451 logic probe pod.... it uses an ecl output comparitor with adjustable reference.... its a 3.5mb download if you are interested
LawrenceG: no thanks -- the specifics probably wouldn't do me much good
what kind of sample rate would you be aiming for if you built a front end?
and how many channels?
jmkasunich: good question. it would be nice if I could cleanly sample any waveform generated by the pluto, which has 40MHz clock.
maybe something I could build 8 channels at a time?
what is the physical connection to the FPGA board?
looks like 40 pin ribbon cables?
the signals are on a 40-pin female right angle header -- gnd, 5v, 3.3v, then 32 channels, then some fpga configuration related pins
20 signals and 20 grounds would be a lot nicer
you aren't gonna be able to send fast signals thru that (at least not very far - single digit inches most likely)
looks like TL3116 comparators are $2 each
those are 9nS
presumably I could modify the fpga firmware to put only 16 I/Os on one connector, and make the other pins grounds
TL712 is 25nS, $1.38
how would you make them grounds?
in the fpga pin assignment
(logic low != ground)
so it wouldn't give any improvement? or just not that much improvement?
if the cable length (at speed of light) is more than about 1/10 the rise/fall time of the signals, you will start to get reflections, etc, and have to do things like terminating resistors
(cable becomes a transmission line, with a characteristic impedance, etc)
if you tie alternate pins to real ground (low impedance), then they act as shields between adjacent signals
and give you a well defined impedance
(tangent -- this fpga supports differential signalling, but they haven't arranged the differential pairs together on the headers. bah. I guess it doesn't matter because Vcco is 3.3v but it doesn't support differential signalling except at Vcco<=2.5v)
this is the version 0 input board, partially populated: http://emergent.unpy.net/index.cgi-files/sandbox/img_7489-medium.jpg
-- then I hook a jumper wire or clip or whatever's handy from the socket to the signal I want to test
but I've only used it on fairly slow (1MHz?) signals
ooh it's late
I have dishes to do
well darn - the VFD I picked out of the dumpster doesn't work
powers up, you can set the parameters and everything, the display and controls work, when you press start the RUN light turns on and the fans start, but no output
or at least, no motor turn
bummer - no output voltage
you can't win every time
got a different drive to work
tested the 50Krpm 400W spindle
broke the 6mm diameter shank of the carbide burr that was in it :-(
was any new orifaces created in any body part?
this is what I was running:
[04:08:33] <jmkasunich> http://www.hgrindustrialsurplus.com/search-products/product-detail.aspx?id=12-275-094&searchtable=2&sortExpression=&SortASC=&pageSize=50¤tPageIndex=0
did you happen to measure the runout on that spindle? how noisy is it compared to a universal motor at speed?
I measured runout unpowered, and got 0.001ish (I was dissapointed)
its not quiet (the motor is AC induction, 300Hz = 18000 RPM or so, then there is a 46 tooth phenolic gear driving a 17 tooth steel one
it definitely has power - before I broke the burr I cut pretty heavy into a piece of 1/16" steel
just handholding the spindle
it didn't slow down under load
Do you know the intended use of the device? -- it looks like a hand-held device in the hgr picture
there is a 20mm diameter by about 1" long machined sleeve just behind the rotating part of the spindle
I think its supposed to mount there
it is a 3-phase induction motor rated at 300 Hz, very much _not_ something you can just plug into the wall
what would be a good price for a 400-500w vfd running off 115VAC be (say on ebay)?
hard to say, couple hundred $ probably
the driver came with one collet (6mm i think you said)?
this one did - none of the others in the box had collets (or tools)
well that's a negative, but it sure looks interesting -thanks for the info!
are you sure that command apt-get build-dep emc2 works on 8.04
micges: What have you done before this?
According to http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Installing_EMC2#On_Ubuntu_6_06_or_8_04_from_source
I also wondered about the apt-get build-dep emc2 which didn't work out of the box
However after trying http://www.linuxcnc.org/index.php?option=com_content&task=view&id=21&Itemid=4
it did work
It doesnt do anything
if you have a stock 8.04 install, you need to add the emc2 repositories to the sources list first
Have you tried the http://www.linuxcnc.org/hardy/emc2-install.sh
If no error is print and no update is done ?
Ok I done it
must have universe repo enabled
Should I add I think I'll add a link to the two scripts for updating the sources.list in the wiki; it really isn't that obvious that you need to run the script...
Isn't universe enabled as a default in 8.04?
I have it since april
Did it work for you simply to enable universe and do nothing else?
If I remember there were a couple more steps beyond adding the repository if you try to build the documentation.
I'll just try it again... :-)
But it may have been an issue with my install of Ly
LyX and friends.
build-dep doesn't pull in the build of html docs
I think it pulls in what you need for pdf docs
Maybe that was what was happening.
How's the robot project?
is anyone online to assist me with what appears to be an smi latency issue?
i have a celeron p3 1Ghz which exhibits overruns every 62 s or so, it looks like SMI so I've installed the SMI patch and have run lsmod to verify that it's loaded but I'm still seeing the same behaviour
I've also disabled onboard lan, usb, sound etc but to no avail
rayh: I got my HNC moving last night on the original control. X motion is smooth but Z is grumbly at low speed. sounds like oscillation maybe? I have control schematics but no amp schematics or adjustment instructions. do you have docs for the amps?
buckie555: what controller do you have on the mobo? (pastebin a lspci -vva)
the graphics are onboard 810,. I tried using the vesa driver instead but it doesn't seem to like it so I've switched back ot the 810 driver which is found by default
I may have in a box out in the garage.
onboard graphics are usually a very probable cause of latency problems, usually sticking a graphics card in helps
I won't be able to look till later in the day.
but the overrun every 64 seconds is definately a SMI issue
alex_joni: I'm not at the machine at present unfortunately but I can try that later today
There are two pots on the drive near the top left when you look.
buckie555: it might be that your controller isn't recognized by the SMI module
They are gain and offset.
buckie555: check http://cvs.gna.org/cvsweb/magma/base/arch/i386/calibration/README.SMI?rev=1.4;content-type=text%2Fplain;cvsroot=rtai
alex_joni: well I don't know for sure. It definately happens every 62s which made me think it was that
see if you see the controller your lspci shows in that list
ok will do
rayh: ok that sounds simple enough. I can unhook the vel input and set offset for no motion, and then hook it back up and adjust gain and see if I can make it sound better.
It hasn't been an issue for me so far because I'm using a mesa 5i20 card so the timing isn't critical but now I'm trying to generate a frequency for a VFD and it's creating veruy bad jitter
rayh: but what I have to do first is get ready and then go to work :-)
buckie555: check http://cvs.gna.org/cvsweb/vulcano/base/arch/i386/calibration/smi-module.c?rev=1.17;cvsroot=rtai
thanks again, I will try it tonight.
you can see a list of the known controllers
heh: BIG FAT WARNING : globally disabling SMI on a box with SATA disks and SATA controller in "legacy" mode, probably prevents disks from working.
alex_joni: ok thanks for the heads up - it's all IDE so it shouldn't be an issue
strangely when I initially applied the smi fix a few months ago I'm sure that I ran the latency test for some time and there were no overruns
buckie555: is this on hardy?
but now I'm not so sure as I have two identical pcs running two different machines and the latency tests I ran this morning both exhibit a 64s overrun
and you're sure rtai_smi is loaded?
it shows using lsmod and i checked the modules dir and the permissions on the .ko file and they look right - also the .conf has the correct entries
I'm assuming that the module doesn't need execute permissions. I set it to the same as the others such as hal and match and they didn't have execute
sorry math - not match
so you think that it happens every 60s definately indicates smi as opposed to onboard graphics?
I'd think so
what kind of latency test did you run?
i followed the instructions in the integration manual
if you run the rtai latency test (cd /usr/realtime-*/testsuite/kern/latency && sudo ./run)
then you need to insmod rtai_smi by yourself
if you just type "latency-test" then I think the rtai_smi gets loaded from rtapi.conf
ah - so there's a chance I'm chasing shadows and the fix is being applied when emc runs normally?
it might be
Just installed the latest hardy; universe seems to be enabled as default....
you need to confirm (by lspci) that rtai_smi is loaded when you run the latency test
ok I'll do that
pmbdk: yeah, that should be.. but if you don't have internet access while you install it might not get enabled by default
alex_joni: Ah... Didn't know that... :-)
in any case I'm not able to do build-dep emc2
pmbdk: hmm.. did you install a fresh hardy? or from the linuxcnc live-cd ?
well I ran lsmod whilst emc was running and saw that rtai_smi was loaded. Is there any way to check the latency whilst the gui is running?
buckie555: if it isn't ok you get a popup
without first fresh hardy
buckie555: if you get no popup error, then you're probably ok
but i'll have to install the emc2 rep
pmbdk: you need to run the script, or add the emc2 repo
ah - the realtime error popup. OK well I've never had one of those since I've installed the patch. Perhaps the stepgen jitter is another issue then
there is no emc2 package in stock hardy repo..
should have been: fresh install
buckie555: probably so.. but to debug that there's need on on-hand machine access :)
so get in here from that machine
ok will do.
alex_joni: i know... just wondered how micges did it without the script
i got that impression... :)
so i simply wanted to try it out... but the linuxcnc rep really needs to be added...
pmbdk: sure it does.. the emc2 info is only in there :)
even if the packages are in the main repo
To summarise (in case you can spot another remiss) I've got a stepgen in mode 2 (quadrature) that generates a 500hz signal. I'm just using phase A and then feeding that via an m5i20 digital out to a vfd.
... most ...
buckie555: maybe you should start with the goal
i'll add it to the wiki section about the source install; it's really not 100% obvious...
and let the current implementation aside
pmbdk: sounds good
OK, the vfd has a configurable frequency input that I'm trying to use to set the spindle speed
ok.. is that variable frequency or variable pulse-width?
I've got it set so that a 500Hz input signal maps to a 100Hz motor frequency
it's variable frequency
the vfd can handle 150-65000 hz
I've got it set so that 500 hz represents 100hz motor frequency and then a linear scale down to 0
the m5i20 io update function is on the servo thread I think
so up to 1kHz updates
and you won't be able to run it at 120 kHz
yes it is - and that sounds about right
you get max 500Hz pulses
hi SWPadnos, back already?
gone yet? :)
too bad.. I'm off to germany on monday
bummer. I won't be back until late September
it'll surely match one day :D
I get a smooth pulse train via the scope upto about 100hz and then after that the width of some of the pulses appears to differ
well, I should have a railpass again - who knows :)
where did you put the stepgen update function?
the very last thing to trigger, make pulses is last in the base thread
not make pulses, the update
the frequency output via the scope looks correct, just some of the pulse width's vary
buckie555: I expect it to jitter at some point
update is also the last called but in the servothread
I would put all the stepgen stuff in the base thread
I thought that update had to be in the servo thread because it uses floats
buckie555: I think you will get better results if you move the stuff to the parport
buckie555: right.. sounds like I'm moronic atm :)
unless there's no work being done in the base thread ...
alex_joni: not at all
the problem you have now is that changes only happen once every 1msec
no the base thread is doing nothing else -
so if you want some odd frequency it will dither between possible frequencies
but the spindle speed cmd rarely changes anyway
ok, for 500Hz you probably want about a 5KHz base thread at minimum, and I'm sure it's faster than that
yeah.. but if you request 333Hz .. it'll output 500Hz for a cycle and 250Hz for 2
have you tried the hostmot2 driver for the mesa? it has hardware step generators
SWPadnos: that is in 2.2.6 .. not yet out
buckie555: either you update your config to hostmot-2 (which has different stuff in the m5i20 FPGA, and includes changing your config)
no not yet. I've currently using all 4 servo axis and most of the io on the m5i20 board. I have got another that I could install though if need be
or you can try moving this to the parport
I'm guessing that hostmot-2 retains 4 axis control but sacrifices some of the io to provide the step generators?
are there any docs for it yet?
<- little clue
sort of, it's more or less completely configurable as to which PWM or stepgens you use
so if you need 4 PWM and 3 stepgen you can do that, but you will of course lose the I/Os for the functions you turn on
basicly you have PWM and stepgens inside the FPGA
those are connected to the same pins as I/O
(then again, you can turn off functions as well, so if you don't need the encoder input for the fourth PWM, you can turn it off and regain those I/Os)
OK - so at the moment I have 4 servo axis control and 16 + 32 IO I believe
and you can select if you want I/O or stepgens or pwm - on certain pins
buckie555: I still think the fastest way to solve this is using the parport
sounds like just the job
yep, that will be fastest
if you want software control of a certain frequency you need at least 4-5 times the output frequency
or 10 :)
I think you could be right. I was hoping to keep everything hooked up via the 5i20 for the optoisolation
[12:25:07] <alex_joni> http://upload.wikimedia.org/math/d/9/a/d9aa24ce7dd8d8defe76adccb3a04237.png
actually this: http://upload.wikimedia.org/math/0/4/1/041a1bdceac794c82b71068862abde6a.png
OK - well the lowest high end frequency that the VFD accepts is 150hz so perhaps I'll see if I can get a stable pulse stream at that and if not I'll probably wait until hostmot 2 is available
you can add parport stuff to the base thread. just add stepgen.0.make-pulses and then parport.0.write
leave stepgen.update in the servo thread
wonder if you could run the m5i20.io-update in teh base thread
(change the names so they're - you know - spelled right :) )
and leave the rest in the servo thread
you should be able to run it at 10 KHz or so
of course not a 25kHz base-thread
buckie555: you can try this: move the io stuff to the base thread, start with the same speed as the servo thread
buckie555, when you have a chance, look at the run time of m5i20.0.digital-out-write (or whatever it's called)
it should be a parameter named something like m5i20.0.digital-out-write.tmax
rings a bell
that will be in CPU cycles, not in nanoseconds
you'll have to convert :)
you only need 5 kHz or so to get a good 500 Hz signal
so as long as the tmax value is < 100 ns or so, you should be fine
i'll check it out
thanks for the help guys - it's much appreciated
on another slightly more worrying issue:
coffee time! ;)
Good idea - coffee first.
Several days ago my other machine running a similar setup hung halfway through a code. AXIS froze and the pc didn't respond to any commands however EMC obviously continued to run in the background as the code succesfully completed. Is there any auditing that I can set or what should I be looking for to try to get some debugging info for finding out whats happening if this happens again?
interesting. how long was the G-code program? (just curious)
not that long compared to some I run - 1000 lines maybe, a few subroutines and about 20mins machine time
ok, and it ran for about 10 minutes or so after the UI had hung?
it was pretty scary as I couldn't do anything but it looked as though it knew what it was doing :-) so I let it carry on with my hand over the e-stop
It finished the motion but the spindle kept running - I'm guessing this would normally be controlled by the gui which had frozen
ok, interesting. IO is handled by a different section of the code than motion
just to be sure, it did a lot of different motions after the hang - not just completing a line or two?
this is the first time it's happened in the 18 months that the machine has been running on average 8 hours a day
no i think it did at least 20 or so lines
and the finishing location was correct
I couldn't even ctrl+alt+f1
ok. I'm pretty sure it just finished out the motion queue, but I wanted to be sure
the interpreter is in userspace, so that wouldn't have run after the crash
FWIW, I've seen much much better RT performance after a crash :)
well, gotta run for a DR. appointment. see you later
:-) I felt like I was playing russian roulette - only with a pretty expensive mold and a 15 hp VMC
the RT system is very robust, so what should happen after a "userspace" crash is that any queued motion will complete, but nothing else will happen
ok - thanks for all the help
so you could end up burning a part/tool since the spindle will still be running once the queue is flushed
(if the tool is still in contact with the part)
luckily, all the coolant will still be on :)
well we always run attended - well, in the same area at least
hmm tis afternoon, and the boss hasnt turned up, and I made a worm and wheel
thought that the worm ate the wheel
it does if you don't give it lube
he behaves with lube?
haha, 5 fill-ups on my credit card statement for last weekend
just been making a replacement set for a customer, he didnt give me the spacing, wheel was nearly bald
and I think I paid cash for one more
carting the new toy home?
it was about 1200 miles
what new toy?
hardinge hnc lathe
it will be my first real emc machine - the mill is working well enough to wait
did you drive the bus?
to get the lathe I mean :)
nope, just a truck and trailer
cradek: "rayh: ok that sounds simple enough. I can unhook the vel input and set offset for no motion,.... "
Unhook the controller side vel input, short the amp side vel input ( this is called nulling the input), then adjust offset, then restore.
If not standstill when reconnected then system is injecting bias ( not from 'offset' pot )
* archivist finally does his thread milling pics and vids http://www.archivist.info/cnc/
I still havent found a nice way to cut gears
hobbing is nice I should add an encoder to the spindle
tha tlooks nice! is the worm acme?
what's it for? I don't recognize it as a clock part.
just happend to have a suitable cutter
its for a 1920's ish amusement machine
is the setup in P1010033 some kind of depthing machine?
vernier height gauge
with a block bolted onto it to hold round things
two parallels and a height guage
1/4" bar to mimic the shaft
oh sure it is - I was zoomed in too far and thought I saw something else
wow, the original is pretty bad
lots of guessing needed from the original
archivist: would a steel worm be better because it would gall less?
used nearest hob 24DP to make the wheel and under sized the worm to match
fenn: certainly but there would be no repeat business
fenn yes but original wasnt
I see that the original failed though...
hehe Ill be dead when the repeats needed
at least it forced me to finish the other axis and learn a bit more gcode
why did you use a rotary table instead of helical milling to make the worm?
now I know I need spindle encoder and a 5th axis
I suppose it would give a slightly better worm
archivist: why do you need that for threadmilling?
better worm and form
isnt the cutter symmetrical all around?
then all the funny shaped escape wheels etc
a couple sine bars would be enough wouldn't they? you could just tilt the rotary.
no more filing
trying to reduce setup time as well
what kind of escape wheel needs 5 axis?
oh right, england
well 4 for that
I'm anxious to make a fusee on my new lathe (after the retrofit)
fusee should be easy now on this, just need the gcode
Daniels has a diagram in his book showing the proper curve - and I don't understand a bit of it
U type trunion with the A axis on so I can tilt for screws and hobbing and 0 90 for the rest
George Daniels? we shook hands at a ceremony
"The above assumes that the fusee curve is to be part of a circle (which from a practical viewpoint is probably satsifactory)" [first google hit, bhi]
must look in his book, I have A.L. Rawlings book as well and he has some on fusee curves
[16:36:28] <cradek> http://books.google.com/books?id=S69BAAAAIAAJ&pg=PA44&lpg=PA44&dq=fusee+curve&source=web&ots=p7K6my5moS&sig=sSZrUQsXruk3_VRxXDvLmHd4gjM&hl=en&sa=X&oi=book_result&resnum=2&ct=result#PPA44,M1
ug Rawling has the evil maths
hmm I have a later version of that at home http://www.collection.archivist.info/searchv10.php?srcdata=title&srcprog=searchv10.php&searchv4page=1&errlev=0&searchstr=Applied+Mechanics+and+Mechanical+Engineering
maybe 1943 will have less fusee info than 1903 though :-)
I have a few others to look in http://www.collection.archivist.info/searchv10.php?srcdata=title&srcprog=searchv10.php&searchv4page=1&errlev=0&searchstr=Jamieson
the elementary version may not have it
my mother-in-law found this clock http://cgi.ebay.com/Working-Antique-Gilbert-Chiming-Mantle-Clock-1903_W0QQitemZ150273625311QQihZ005QQcategoryZ13853QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
it dings at the half hours and chimes at the hours. sound nice.
[17:03:26] <skunkworks_> http://www.cnczone.com/forums/showthread.php?t=61690
Just this once .. here's the log: http://www.linuxcnc.org/irc/irc.freenode.net:6667/emc/2008-07-24.txt
skunkworks_: looks like you gave good advice. maybe the parport doesn't work right.
I am interested in finding out some info on the lathe threading capabilities of emc2. Is anyone familiar with this aspect?
yes I am
cradek, how accurate is the phase of thread starts with emc? I am interested in using it in an application where the angle of the start must be accurate within 2 degree. Is this achievable?
yes it is accurate to the resolution of your spindle encoder, since every threading pass starts with an index pulse.
cradek, can the start of the pass be offset from the index pulse, or is it bound to the pulse?
it is bound to the pulse. to do multistart threads for instance, you would need to offset the pass's start in Z.
I see. Would a single pulse/rev be adequate for good accuracy?
in the development version of emc2, there is very new support for that configuration. In the released versions you need an encoder.
cradek, does the documentation have any recommended encoder hardware?
I have not ever used single pulse/rev so I cannot say how well it works, except that I am wary because I have seen some poor quality threads cut this way.
gotnone: there is a lot of supported hardware that reads encoders. also for a spindle encoder you could read it in software because it does not need a super high resolution or high speed.
I have cut lots of threads on a lathe with the spindle encoder hooked directly to a parallel port.
on your setup, how many inputs/rev does your parallel port recieve?
the parport can be read every 20 microsec, so if you think about the maximum rpm you want to use to thread, you can derive the correct number of lines for your encoder
I am not sure what mine was. I have encoder reading hardware now on that lathe, and a 1024 line encoder I think.
I meant 'can be read ABOUT every 20 microsec' - depending on your computer it may be more or less.
(I think all modern machines can do 20 microsec pretty easily.)
Ok thanks for the tips.
cradek, I found some good resources under cnczone too.
for emc2 information, our mailing lists are probably better than cnczone
nice archive: http://news.gmane.org/gmane.linux.distributions.emc.user
[19:26:19] <cradek> http://search.gmane.org/search.php?group=gmane.linux.distributions.emc.user&query=spindle+encoder
^ I love that..
[19:38:41] <skunkworks_> http://jmkasunich.com/pics/fusee-DSC00563.jpg
skunkworks, thanks for the link. Thats some neat stuff.
[20:11:54] <acemi> http://www.linuxdevices.com/news/NS4282988768.html
little help with a jog wheel????
when i spin the jogwheel slowly the axis moves smoothly, when i spin it quickly, the axis jerks and stutters and even doesn't make any motion progress??? what is going on?
in jog-vel-mode. nothing else really out the ordinary.
can you post your hal files?
i'm running in torque mode and still doing a bit of tuning, but that's a separate problem.
hmmm. at first glance, that looks quite convoluted :)
that's just my selection stuff. the first section is just that - first. can be done easier. look at the jog section, and the actual encoder area.
well, I'm assuming that you've left the servo period at 1 ms, and that the 5i20 digital read function is in that thread, right?
i believe so.
and this jog thread is 5x slower, running at a 5ms period
the jog thread is only for the switches. (supposed to be)
SERVO_PERIOD = 1000000
from the ini file.
except that you put the encoder count and capture functions into the jog thread, not the servo thread
so it can only count once pre 5 ms, or at 200 Hz
however, the encoder omdule is in 1x mode, which I think means that it only counts full cycles, not each edge
where is a good place to purchase a 100 ohm 10 turn pot?
that means that you only get at most one count every 20 ms
that's probably it. i will change it now and see what happens.
even at the servo rate, you'll be limited to 250 counts/sec (which should be OK with a 100-count/rev handwheel - that's 150 RPM :) )
wow - I didn't know they made 0.2% pots
SWPadnos, you're a genius !!!!! thanks for the 2nd set of eyeballs.
now back to tuning.
I'm willing to bet that the selection and scaling can be done a lot simpler
yeah, i'm sure they can. gotta get is working for monday. then i can make it pretty.
i'm integrating into an existing panel (delta tau)
that was easy
I added diodes before the input of the comparator.. good/bad/indifferent?
with the .012 ohm resistor... I would never get to .6v
but it would take care of any cool spikes.
what kind of resistor has 4 terminals?
kenvin config.. :) yes I just learned that.
[23:38:20] <skunkworks> http://www.ohmite.com/cgi-bin/showpage.cgi?product=10_series#four
ah, Kelvin :)
I knew what I ment..