#linuxcnc Logs

Dec 02 2020

#linuxcnc Calendar

12:01 AM pfred1: I just got done setting kicad up yesterday
12:07 AM pfred1: I'd been putting it off for quite some time it's such a joy to do
12:07 AM pfred1: I like having the library files local I'm not int othe giyhub connection
12:07 AM pfred1: github even
12:07 AM pfred1: nothing against github but I just don't like the whole internet computing idea
12:07 AM pfred1: I'm not into the cloud
12:55 AM Deejay: moin
04:49 AM -!- #linuxcnc mode set to +v by ChanServ
04:54 AM JT-Cave: morning
05:14 AM -!- #linuxcnc mode set to +v by ChanServ
05:45 AM Tom_L: morning
05:46 AM XXCoder: heys
05:58 AM Tom_L: 33F hi 47
05:58 AM Tom_L: rain on the way and possibly snow / ice tomorrow
05:59 AM XXCoder: wow almost frost nights. 31 to 37. days 47 to 49
08:20 AM unterhaus_: well, the trash men didn't get Monday off to go hunting like they used to do
08:21 AM unterhaus_: wish they would get rid of sunday hunting again
08:22 AM unterhaus_: sounded good in theory, but putting the first day of hunting season on a Sunday is just another example of the Man keeping the little guy down
08:39 AM -!- #linuxcnc mode set to +v by ChanServ
08:54 AM TekniQue: I went and wired my mill up to the Mesa card last night, works fine except I seem to be missing steps, something about my stepper drivers is not right. I scoped the output of the Mesa card and it's perfect with no load on it but I'm wondering if maybe its output current is on the weak side when driving the stepper driver
09:24 AM gloops: what size steppers TekniQue ?
09:28 AM pcw_home: TekniQue: you might try doubling the step time.
09:28 AM TekniQue: nema 23 steppers
09:29 AM TekniQue: I adjusted the step time and it changed the sound of the steppers
09:29 AM TekniQue: I'm going to scope the waveform tonight hopefully
09:29 AM TekniQue: see if my suspicion is right
09:30 AM pcw_home: I would make the step time as long as possible (until it interferes with the maximum step rate)
09:31 AM unterhaus_: what drivers?
09:32 AM gloops: voltage near max, current up
09:33 AM gloops: acceleration often one to look at too
02:34 PM TekniQue: is it possible for my Mesa 7i92 to have different drive strengths on different pins?
02:34 PM TekniQue: because my Y and Z axis are working beautifully
02:35 PM TekniQue: but the X axis just won't work very well
02:35 PM TekniQue: on the bench I get beautiful square waves on all pins
02:35 PM unterhaus_: It isn't the mesa
02:35 PM TekniQue: but attahed to the mill the X step voltage is very low
02:36 PM unterhaus_: different cable or same cable?
02:36 PM TekniQue: I just put it inside the cabinet with the drivers
02:36 PM TekniQue: and plugged the DB25 connector into the board directly
02:36 PM unterhaus_: X step voltage meaning the mesa output?
02:36 PM TekniQue: that used to go to the parallel port
02:37 PM TekniQue: yes
02:37 PM TekniQue: just wondering if there is a software setting for drive current
02:37 PM TekniQue: because the manual hints at it
02:38 PM unterhaus_: what were you doing before that wasn't plugging directly into the 25 pin?
02:39 PM unterhaus_: are you saying you were measuring the output of the 7i92 without anything connected?
02:39 PM TekniQue: yes
02:39 PM TekniQue: but now measuring with it connected, I'm getting a weak output on that one pin
02:39 PM TekniQue: and missing steps
02:39 PM unterhaus_: your breakout board is dragging down the voltage
02:39 PM TekniQue: there is no breakout board
02:39 PM TekniQue: and it was working yesterday plugged into the parallel port
02:39 PM TekniQue: *shrug*
02:40 PM TekniQue: I'll figure it out
02:40 PM TekniQue: it's just a bunch of wires soldered to the DB25 connector
02:40 PM TekniQue: going directly to the stepper drives
02:40 PM TekniQue: and the stepper drives just have optocouplers on their inputs
02:40 PM TekniQue: really not much there that can go wrong
02:41 PM TekniQue: but they need enough current to trigger the optocouplers
02:41 PM unterhaus_: how hard is it to swap drives?
02:42 PM unterhaus_: if I did something and pcw did something and it doesn't work, my first assumption is that it's my fault
02:45 PM pcw_home: <TekniQue> if you use a 7I92 (or other Mesa FPGA card) to drive a high current OPTO, you must wire the outputs in sinking mode
02:47 PM pcw_home: that is OPTO+ to 5V OPTO- to 7I92 output and step output polarity reversed
02:49 PM TekniQue: ok the low voltage I was seeing was just a bad connection of the oscilloscope probe, it looks like my stepper driver is dying
02:49 PM pcw_home: This is because the 5V tolerance circuit only allows sourcing to 3.3V but it will sink to ground
02:50 PM TekniQue: yeah that explains a thing actually
02:50 PM TekniQue: good call
02:50 PM TekniQue: I'll swap the common wire for all the drives to +5
02:50 PM pcw_home: the output will be at 5V high when unloaded but that's just because they have pullup resistors
02:51 PM TekniQue: I need to swap the opto for the spindle on/off also
02:51 PM TekniQue: because the way the Mesa card works the drive just runs all the time
02:51 PM TekniQue: unless linuxcnc is running
02:51 PM pcw_home: you typically also need to invert the step output polarity in hal
02:52 PM TekniQue: with the parallel port it wasn't a problem because I would boot the PC before turning on the power to the mill
02:52 PM TekniQue: but with the mesa card the card is powered from the mill power supply
02:52 PM TekniQue: and it has to start up before linuxcnc starts or linuxcnc won't start
02:53 PM TekniQue: refuses to start unless the ethernet port has link
02:53 PM pcw_home: also the mesa I/O pins idle high so external circuitry should be active low
02:54 PM TekniQue: yes I have noticed that
02:54 PM TekniQue: hence my comment about the spindle control
02:54 PM pcw_home: If you are using bare FPGA I/O beware of grounding pins to frame ground. this will often kill that pin
02:54 PM TekniQue: I use nothing but optos
02:54 PM TekniQue: everything is isolated
02:55 PM TekniQue: because you know, it's not fun to kill a parallel port
02:55 PM TekniQue: so I made everything isolated when I built the machine many years ago
02:56 PM pcw_home: (the low side clamp diode will be killed by ground noise which is often 1-2V AC HF)
02:57 PM pcw_home: you can protect against this with a 100 or so ohm series resistor that limits current into the diode
03:08 PM TekniQue: how do I invert the stepper signal in hal config?
03:08 PM TekniQue: wasn't there a man page that lists what the hal can do
03:09 PM TekniQue: do I do it on the pin or on the stepgen?
03:10 PM pcw_home: its a parameter, let me see... hm2_7i92.0.stepgen.00.step.invert_output
03:10 PM pcw_home: for stepgen 00
03:11 PM pcw_home: (which is an alias for a gpio pin but much more portable)
03:11 PM TekniQue: ok so I almost had it right
03:12 PM pcw_home: normal polarity for step is active high, if you set invert_output true the output will be active low
03:13 PM pcw_home: (you may need to invert direction also)
03:39 PM andypugh: LinuxCNC is a linux-based open-source CNC control. | Latest release: 2.8.1 | http://www.linuxcnc.org | Register with freenode before speaking
03:40 PM andypugh: OK, so I am not important enough to swith the topic.
03:42 PM Tom_L: you're not op?
03:44 PM andypugh: I am not sure. I have “voice” and appear at the top of the list.
03:46 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Music_Desk_rail.jpg
03:46 PM Tom_L: this afternoon's project
03:47 PM andypugh: If you had used D~elrin it would have been the right colour.
03:47 PM Tom_L: good point
03:55 PM -!- #linuxcnc mode set to +o by ChanServ
03:55 PM jymmmm: andypugh: NOW you can change the topic
03:56 PM JT-Shop: ah you need the green button
03:57 PM andypugh changed topic of #linuxcnc to: #linuxcnc LinuxCNC is a linux-based open-source CNC control. | Latest release: 2.8.1 | http://www.linuxcnc.org | Register with freenode before speaking
03:57 PM JT-Shop: yea
03:57 PM Tom_L: is green op?
03:57 PM Tom_L: blue voice?
03:58 PM andypugh: It might depend on the client software
03:58 PM Tom_L: gee i thought everybody used hexchat :)
03:58 PM jymmmm: Tom_L: telnet
04:00 PM andypugh: I am on a Mac so the highlights are Cerise, Taupe and Verditer
04:00 PM jymmmm: lol @ andypugh
04:09 PM TekniQue: going active low fixed my missed steps
04:09 PM TekniQue: stepper driver just wasn't quite happy with 3.3 volts
04:10 PM pcw_home: They are almost all designed for 5V signals
04:21 PM TekniQue: yeah funny thing with tolerances of that
04:22 PM TekniQue: you can usually get away with feeding 3.3V signals to an input expecting 5V logic
04:22 PM TekniQue: but sometimes it bites you in the ass
04:22 PM TekniQue: occasionally
04:22 PM TekniQue: 2 out of 3 drives worked flawlessly
04:30 PM Tom_L: andypugh, what changed between 2.8.0 and 2.9.1?
04:31 PM Tom_L: andypugh, what changed between 2.8.0 and 2.8.1?
04:31 PM andypugh: Bugfixes, mainly
04:31 PM Tom_L: any updated news on that RTAI fix?
04:31 PM andypugh: No, that’s a different issue.
04:32 PM Tom_L: right, i was just curious
04:36 PM TekniQue: just one remaining question I hope, I had offets stored on my old machine, G54, G55 etc etc
04:36 PM TekniQue: how can I restore those on the new machine?
04:37 PM TekniQue: What file keeps them
04:38 PM Tom_L: .var
04:38 PM Tom_L: yourmachine.var
04:39 PM Tom_L: http://linuxcnc.org/docs/2.8/html/gcode/g-code.html#gcode:g54-g59.3
04:39 PM Tom_L: stored in those 'memory' locations
04:58 PM TekniQue: perfect
04:59 PM TekniQue: where do I adjust what the DRO in Axis displays?
05:00 PM TekniQue: found it
05:00 PM TekniQue: view menu
05:22 PM TekniQue: well that works, ran one of my old NC files and it cut just like on the old controller
05:22 PM TekniQue: except the steppers sound a lot different
05:22 PM TekniQue: clearly there was considerable jitter on the old parallel port setup that isn't present with FPGA control
05:34 PM JT-Cave: whew a long day...
05:34 PM XXCoder: welcome back
05:35 PM TekniQue: JT-Cave: I finally found the time to get my mill running with the mesa card, thank you for that recommendation
05:36 PM JT-Cave: great
05:42 PM JT-Cave: jymmmm, how did you change andy to an operator?
05:44 PM XXCoder: tek nice
05:46 PM Tom_L: JT-Cave, jymmmm is anop
05:46 PM Tom_L: iirc
05:47 PM JT-Cave: what is that?
05:50 PM XXCoder: an op
05:50 PM XXCoder: hes one of ops in here I guess? heh
05:51 PM JT-Cave: how can I become an op on my channel ##chickens
05:51 PM XXCoder: if you made channel should do it with just /op
05:51 PM XXCoder: wait hmm
05:51 PM XXCoder: forgot what command to nickserv to get op if owner
05:52 PM XXCoder: try /op JT-Cave there see if it works
05:53 PM JT-Cave: ##chickens :You're not a channel operator
05:53 PM JT-Cave: hmm, I think I created it with another nick
05:53 PM XXCoder: yeah forgot how to get op if owner of channel
05:53 PM serp: if you are the only one in that channel, leave and rejoin
05:53 PM serp: is it even registered with freenode?
05:54 PM JT-Cave: I guess it is, been a while since I started it
05:54 PM JT-Cave: no there are me three times and two other in there
05:55 PM serp: if it is registered with freenode you'll have to do it through chanserv... you can send a message to chanserv that just says help
05:55 PM JT-Cave: ok
05:55 PM XXCoder: oh yes chanserv been a while lol
05:56 PM JT-Cave: hmm no reply from ChanServ
05:57 PM serp: interesting i get a very long reply.. it replies as notice though
06:00 PM JT-Cave: well chow time here...
06:04 PM JT-Cave is now known as jthornton
06:27 PM Tom_L: jthornton, if you're the founder you can
06:37 PM jymmmm: JT /msg chanserv op #linuxcnc andypugh
06:38 PM -!- #linuxcnc mode set to +o by ChanServ
06:39 PM -!- #linuxcnc mode set to -o by ChanServ
06:39 PM jymmmm: JT /msg chanserv deop #linuxcnc JT-Shop