#emc | Logs for 2008-03-08

[00:07:04] <BigJohnT> tink tink
[00:13:32] <BigJohnT> UPS is here
[00:15:16] <BigJohnT> yea! I can make molex plugs
[00:16:47] <BigJohnT> damm, no fricking instructions
[03:37:34] <cradek> SkinnypuppY34: still no luck! when I crack the hard injector lines I get fuel dribbles from two but not the third. no sign of it firing (but it's much colder today)
[03:40:20] <jmkasunich> cradek: what kind of diesel?
[03:40:40] <cradek> a little 3-cylinder generator
[03:40:44] <cradek> looks like a small car engine
[03:40:51] <jmkasunich> unknown make?
[03:41:08] <jmkasunich> (I have some very limited experience with a one-cylinder Yanmar diesel
[03:42:19] <cradek> I had a bit of data - looking
[03:44:01] <gezar> hmm, been reading the tool changer posts, very interesting
[03:44:28] <gezar> had a barafaldi go completely nuts on me once, completely disapointed me and the customer at the time
[03:44:45] <cradek> http://www.martindiesel.com/Products/Generators/55-DS%20to%204405-DS%20Series.htm
[03:45:07] <cradek> it's marked 1000-DS, 10.5kW
[03:45:15] <cradek> so the part numbers have changed
[03:45:15] <jmkasunich> thats not exactly small
[03:45:20] <cradek> but it looks just like that pic
[03:45:41] <cradek> no, I guess it's not small
[03:45:44] <gezar> nice you got it running?
[03:45:48] <cradek> nope
[03:45:53] <SkinnypuppY34> cradek , no fuel from the third line?
[03:45:58] <jmkasunich> electric start I assume?
[03:46:00] <cradek> SkinnypuppY34: nope
[03:46:09] <cradek> jmkasunich: yes it has what looks like a car starter
[03:46:18] <cradek> SkinnypuppY34: and no sign of firing on the other two
[03:46:31] <jmkasunich> can you tell if it has compression?
[03:46:35] <cradek> maybe there's still air - I'm not sure how to tell
[03:46:52] <jmkasunich> (if it has a hand crank you can feel it, with a starter its harder)
[03:46:52] <gezar> do you know how long it had been sitting?
[03:46:55] <cradek> jmkasunich: good question.
[03:47:01] <cradek> gezar: at least two years
[03:47:19] <jmkasunich> the yanmar's I've messed with (sailboat engines) had electric start with hand crank backup
[03:47:25] <gezar> cradek: your going to need to reprime it, more then likely fuel has gone jelly in the injectors
[03:47:45] <cradek> this one has no provision for hand crank - way too big I bet
[03:48:07] <jmkasunich> yeah - the one I messed with was 8HP, less than 6kW equivalent
[03:48:19] <gezar> I would bleed the fuel system
[03:48:38] <SkinnypuppY34> Is there a clear sight bowl ? Is the fuel clear or clouded if so?
[03:48:55] <cradek> there is nice clear fuel everywhere I've looked
[03:49:01] <cradek> yes the bowl is glass just like in that photo
[03:49:14] <jmkasunich> banjo fittings at the injectors, right?
[03:49:24] <cradek> no, flanges
[03:49:27] <gezar> hmm
[03:49:31] <jmkasunich> flanges?
[03:49:46] <jmkasunich> fuel line to injector is flanged?
[03:49:49] <gezar> can you tell if your getting fuel in the cylinders? does it have that "smell" to it when your tring to start it?
[03:49:52] <SkinnypuppY34> tubing flare
[03:49:56] <cradek> the pipe is flared, a compression fitting presses it into a taper on the injector
[03:50:06] <jmkasunich> ah, flared, not flanged
[03:50:45] <cradek> gezar: I kind of don't think so. it doesn't stink like it should
[03:50:59] <cradek> hard to tell, there's diesel everywhere
[03:51:03] <jmkasunich> you're getting dribbles of fuel at two of three injectors when cranking, so you know you have delivery, but you don't know if you have pressure (to make the injectors do their thing)
[03:51:11] <cradek> right
[03:51:14] <SkinnypuppY34> Cradek , pull the return off the injectors and put in a small bottle with diesel in it, look for bubbles while you crank over
[03:51:34] <cradek> and one clearly has a problem with delivery
[03:51:49] <gezar> delivery to the injectors or from the injectors?
[03:51:53] <cradek> to
[03:51:58] <jmkasunich> is there anything at all at the third? even air bubbles?
[03:52:23] <gezar> and the pump is working really good right?
[03:52:25] <cradek> I wouldn't be able to tell if it was pumping air. but certainly no fuel
[03:52:41] <gezar> could be a clog from sitting, something plastic may have broken down over time
[03:52:45] <cradek> gezar: I don't really know how to tell.
[03:52:59] <gezar> you can always make a mess :)
[03:53:00] <jmkasunich> what kind of connections at the injection pump end of the pipes? can you disconnect that end and look for fuel delivery from the injection pump?
[03:53:24] <cradek> same compression fittings. I loosened the bum one at that end - nothing there either
[03:53:35] <jmkasunich> hmm, thats not encouraging
[03:53:44] <gezar> what about the line comming out of the pump?
[03:53:53] <gezar> can you disconnect it and see if it squirts out?
[03:53:53] <cradek> the pipes are only 8" or so
[03:54:09] <jmkasunich> I'd be tempted to disconnect all three at the pump
[03:54:28] <jmkasunich> its like a distributer - you should get timed spurts of fuel from each of the three ports
[03:54:52] <cradek> spurts or dribbles?
[03:55:03] <gezar> you sure about that? thought it would be constant pressure at the in end of the injectors
[03:55:22] <cradek> gezar: on gas yes (electric trigger), diesel no
[03:55:28] <jmkasunich> spurts - theres not a lot of volume per injection, but if there injector was connected it would be 1000+ psi
[03:55:29] <gezar> oh i see
[03:56:06] <jmkasunich> if you just crack the connection, you will see a dribble as it creeps through the threads, etc
[03:56:17] <cradek> that's what I've done so far
[03:56:19] <jmkasunich> if the tube is removed, you should see a small spurt from each port
[03:56:30] <cradek> ok that's easy to spot then
[03:57:00] <jmkasunich> you might even try putting a finger over the pump discharge to see if you feel a pressure pulse
[03:57:20] <jmkasunich> (after you see that it isn't generating a powerfull spurt - don't want subdermal injection of diesel fuel
[03:57:24] <cradek> yeah I'll think twice before doing that...
[03:57:38] <cradek> I have a deep respect for that pressure because I haven't worked with it before
[03:58:32] <SkinnypuppY34> See the delivery valve in this diagram, it's what the hardline goes into . You can take off the line and take it out to check it out.http://www.cs.rochester.edu/u/jag/vw/engine/fi/YANMARVESmall2.GIF
[03:58:53] <jmkasunich> I'm not sure exactly what you will see in termsl of scale - it may just be one drop per injection cycle - but whatever you see should be similar at all three ports
[03:59:01] <cradek> bigger: http://www.cs.rochester.edu/u/jag/vw/engine/fi/YANMARVE.JPG
[03:59:45] <cradek> wow that looks complex
[03:59:52] <jmkasunich> does your pump look like that (on the outside)?
[04:00:23] <jmkasunich> I'm what the actual make of your engine is
[04:00:32] <jmkasunich> martin made the genset, not neccessarily the engine
[04:01:10] <cradek> I guess I can't say whether the pump has that configuration
[04:02:15] <SkinnypuppY34> Here's an image heavy rebuild of a rotary style pump. Yours differs instead of having a wavy washer cam it's more like a car camshaft
[04:02:31] <SkinnypuppY34> http://www.vwdieselparts.com/forum/viewtopic.php?t=6694
[04:03:01] <cradek> yes I think it's like a camshaft. I can see the driving gear under an oil filler cap
[04:03:29] <jmkasunich> are the three outlet ports arranged in a circle or a line ;-)
[04:03:38] <cradek> line
[04:03:45] <jmkasunich> camshaft ;-)
[04:08:42] <cradek> http://www.martindiesel.com/Products/Generators/105%20-DS%20Tech%20Info.htm
[04:08:48] <cradek> I suspect the engine is YANMAR
[04:08:56] <jmkasunich> I was leaning that way
[04:09:14] <jmkasunich> stupid things like paint color - far from conclusive, but it had me wondering
[04:09:22] <cradek> http://www.bellpower.com/yanmar3tnvspecs%20oct06.htm
[04:09:40] <cradek> the 3TNV70 is a 3 cyl
[04:10:26] <cradek> oh 9L, way too big
[04:10:45] <jmkasunich> 9l?
[04:11:11] <SWPadnos> 0.854
[04:11:16] <jmkasunich> yeah
[04:11:33] <jmkasunich> and the HP numbers are reasonable too
[04:11:33] <cradek> oh, a typo, I see
[04:11:43] <cradek> maybe I missed a tag. I'll go look.
[04:11:58] <SWPadnos> http://www.yanmar.com/store/item.asp?ITEM_ID=97&DEPARTMENT_ID=56
[04:12:00] <SWPadnos> the modern version
[04:12:07] <jmkasunich> http://www.bellpower.com/Engine%20Literature/TNVSeries1Lit.pdf
[04:12:13] <jmkasunich> compare the drawing there to your engine
[04:12:36] <SWPadnos> http://www.martindiesel.com/Old/70-125.htm#MODEL%20%20%20100%20-%20DS
[04:12:52] <SWPadnos> closer, but not quite the identical model number
[04:16:29] <gezar> I would have to check the pumps output, it probably doesnt build up any pressure unless there is something there to build it up on
[04:16:50] <cradek> woo
[04:17:18] <jmkasunich> woo?
[04:17:23] <cradek> model 3TN82E-HD disp 1.362 HP 13.5/16.5 (cont/peak?)
[04:17:42] <jmkasunich> so, you know the make and model - thats a big step
[04:18:43] <SWPadnos> incidentally, the martindiesel web site says that they have documentation for older models. you can email/call them to get a copy
[04:21:00] <SkinnypuppY34> Any chance it's pointing nose downhill? The third could be where the majority of the air in the pump body is
[04:21:16] <cradek> it's quite level
[04:23:25] <cradek> http://cobweb.ecn.purdue.edu/~dbuckmas/teaching/ASM345/Information%20&%20Presentations/Engines/Deere%20220%20CTM03.pdf
[04:24:16] <jmkasunich> woo hoo
[04:30:22] <jmkasunich> cradek: was the motor in known working condition, and stopped working after being in storage or something? or is it newly acquired, etc, and might be busted because somebody was messing with it?
[04:31:00] <cradek> it is totally unknown
[04:31:13] <jmkasunich> you just got it?
[04:31:21] <cradek> it has 500ish hours on the hour meter. so it's almost new.
[04:31:27] <cradek> yes
[04:33:32] <cradek> darn, this document doesn't have the bleed procedure
[04:34:03] <jmkasunich> CAUTION: Escaping fluid under pressure can
[04:34:03] <jmkasunich> penetrate the skin causing serious injury.
[04:34:03] <jmkasunich> If ANY fluid is injected into the skin, it must be
[04:34:03] <jmkasunich> surgically removed within a few hours by a
[04:34:03] <jmkasunich> doctor familiar with this type injury or
[04:34:03] <jmkasunich> gangrene may result.
[04:34:17] <jmkasunich> that'll put the fear into you
[04:35:24] <cradek> I already had it, but yeah
[06:43:11] <ChanServ> [#emc] "This is the #emc channel - talk related to the Enhanced Machine Controller and general machining. Website: http://www.linuxcnc.org/, wiki at http://wiki.linuxcnc.org/"
[10:12:00] <fenn> yeesh this is what happens to your dreams when you read vinge's "synthetic serendipity" novels http://fennetic.net/dreams/the_google_project
[10:51:45] <jlmjvm> alex_joni:good morning
[16:32:05] <skunkworks> http://www.youtube.com/watch?v=O3d0fueNr30
[18:04:56] <JymmmEMC> love the MOVING ESTOP button
[18:06:30] <JymmmEMC> WOW, instead of rails, he's using bars
[18:06:37] <JymmmEMC> for the Y
[18:23:12] <JymmmEMC> Hey, does everyone have photos of their controller up some where that I could look at? I'm looking for ideas.
[18:25:21] <skunkworks> Guest614: hello
[18:25:45] <skunkworks> JymmmEMC: I have nothing
[18:26:17] <skunkworks> JymmmEMC: http://www.electronicsam.com/images/KandT/servostart/breakout.JPG
[18:26:33] <skunkworks> it doesn't get any better than that
[18:28:16] <skunkworks> JymmmEMC: http://www.mpm1.com:8080/machines/GandL/pictures/S1030255.JPG
[18:30:32] <JymmmEMC> looking...
[18:31:29] <JymmmEMC> skunkworks: the 2nd link is real slow
[18:32:13] <skunkworks> yes it is. He is self hosting I think
[18:32:21] <skunkworks> this is stuart stevensons stuff
[18:32:26] <JymmmEMC> ah, gotcha
[18:32:55] <renesis> hello machine hax0rz, how are this fine day?
[18:33:50] <renesis> you guys should all beg twingy for mousing support, and then put the GCAM in the emc
[18:34:08] <fenn> gcam is a cam program, why would it go 'in the emc'?
[18:34:37] <fenn> you can specify filter programs to use for certain file types already
[18:34:37] <JymmmEMC> cad + CAM + controller (emc) == complete pkg
[18:35:13] <JymmmEMC> OS + cad + CAM + controller (emc) == complete pkg
[18:35:26] <fenn> maybe the request should have been, 'put it on the liveCD'
[18:38:49] <fenn> JymmmEMC: get some cardboard, make various mock-ups and try out different operations with your hands
[18:39:19] <fenn> stick the buttons on the cardboard if you like
[18:39:34] <JymmmEMC> fenn: That's what I have been doing. It's not so much the front panel as much as inside the chassis that I need ideas for.
[18:39:57] <fenn> oh. well.. anything's better than a rat's nest
[18:40:20] <skunkworks> its all a rats nets - it is just how well you clean it up ;)
[18:40:40] <fenn> i took apart a tv once that had these u-shaped clips that hold the wires together.. hang on lemme get a pic
[18:40:50] <JymmmEMC> fenn: I have a full tower PC case that I considered, but the layout isn't much better than these other aluminum chassis that I have. So, I just wanted to see what others have done.
[18:41:33] <skunkworks> cnczone search would probably bring up a lot of ideas
[18:41:46] <skunkworks> have you looked at jmk's setup?
[18:41:48] <JymmmEMC> It's just going to be tight as hell either way, it seems.
[18:41:54] <JymmmEMC> skunkworks: no, url?
[18:42:12] <JymmmEMC> brb, have to grab the other PS for dry fitting
[18:43:12] <skunkworks> http://jmkasunich.dyndns.org/cgi-bin/blosxom/shoptask/box-work-02-13-07.html
[18:43:27] <skunkworks> he has more pictures - you would have to look around
[18:44:57] <fenn> JymmmEMC: http://fennetic.net/pub/camera/DCP_0800.JPG
[18:45:11] <fenn> good for if you're going to be taking it apart and putting back together a lot
[18:45:28] <fenn> they also make those things that mount to a panel (snap in or threaded)
[19:04:37] <renesis> because moving the cam into the controller package is new era sexy stuff
[19:04:39] <Twingy> I'm working on a debian package soon
[19:05:11] <Twingy> time is limited with grad school
[19:05:44] <renesis> youre scaring me
[19:07:12] <renesis> i need to make a robot that runs the cnc machine
[19:07:19] <Twingy> whenever it makes sense to put it on the live cd works for me
[19:07:52] <renesis> did your next semester start yet?
[19:08:01] <Twingy> yea, almost half way through it
[19:08:14] <renesis> its quarters or semesters?
[19:08:19] <Twingy> semester
[19:08:28] <Twingy> I still need to figure out what I'm taking this summer
[19:08:51] <renesis> quarter system at pomona looks neat, everying in BSEE is really specific
[19:09:04] <Twingy> I'd like to go to school in australia where they don't really do tests
[19:09:31] <renesis> its all lab and documentation evaluation or something?
[19:09:38] <Twingy> yea
[19:09:46] <Twingy> makes more sense
[19:09:56] <Twingy> more interactive
[19:09:59] <renesis> yeah, for engineering and science at least
[19:10:10] <Twingy> well for anything really
[19:10:20] <Twingy> more interaction = good (if you don't already know the subject)
[19:10:32] <Twingy> testing is good when you don't want to spend a lot of time and already know most of the subject
[19:10:39] <renesis> yeah all my non tech classes getting all group style
[19:10:55] <renesis> teachers barely lecture now, they just kinda kick it with the class
[19:11:01] <Twingy> that's cool
[19:11:04] <renesis> moderate discussions
[19:11:05] <renesis> yeah
[19:11:11] <Twingy> ren, do you have working compile env now?
[19:11:13] <renesis> tech still lecture
[19:11:24] <renesis> but then you do lab and youre pretty much by yourself with a machine
[19:11:29] <Twingy> fillet stuff is committed and just about done line stuff
[19:11:45] <renesis> no im reinstalling windows this weekend tho
[19:12:10] <renesis> basically organizing some media stuff and throwing on DVD and portable hdd
[19:12:12] <Twingy> everyone is reinstalling windows
[19:12:20] <Twingy> my gf is complaining her windows box crapped out and has to reinstall
[19:12:25] <renesis> its beenmaybe a year
[19:12:27] <renesis> i deserve it
[19:12:33] <Twingy> I keep telling her to run ubuntu but she says she needs photoshop
[19:12:37] <renesis> you dont have to reinstall
[19:12:45] <renesis> its just such a bitch to get it back to like it was
[19:12:54] <renesis> reinstall is like 10x faster
[19:12:59] <renesis> and easy
[19:13:18] <Twingy> well she's gotten used to using all this software she didn't pay for
[19:13:28] <Twingy> and has no way to get it back if she reinstalls
[19:13:38] <renesis> aaah
[19:13:49] <Twingy> so I'm like, go buy it or stop pirating
[19:13:55] <Twingy> she's like I can't afford it
[19:13:55] <renesis> i keep confirmed working shit i know ill reuse
[19:14:02] <renesis> no one can
[19:14:13] <Twingy> then I'm like use open source equivilents
[19:14:21] <Twingy> she's like gimp is crap
[19:14:22] <renesis> $1K for a box and $3K for software, f that
[19:14:24] <renesis> yeah
[19:14:26] <renesis> no
[19:14:30] <Twingy> I'm like, whatever
[19:14:34] <renesis> she doesnt take time to figure out the dialogs
[19:14:42] <renesis> its almost the same for 75% of stuff
[19:14:44] <Twingy> she's used gimp for some time
[19:14:57] <Twingy> she says stuff like her sketch pad won't work
[19:15:00] <renesis> and 25% it isnt the same functionality, you prob dont need
[19:15:09] <renesis> ooh
[19:15:23] <renesis> i cant stand adobe stuff anymore, tho
[19:15:49] <renesis> i can totally scale crop and color correct 5 or 6 images in the time it takes ps to load
[19:16:51] <renesis> and if im just scaling screen caps and exports from CAM programs, i prob dont want another monolith app running =\
[19:18:25] <renesis> CAD is like only thing isnt very good for free, cross platform
[19:18:58] <renesis> qcam is decent autocad clone, but i dont think any has it ported for windows
[19:20:34] <Twingy> it doesn't really have 3d support though
[19:20:37] <Twingy> it's all gnuplot based
[19:20:59] <Twingy> and most of the stuff I do is assembly based
[19:21:10] <Twingy> bending sheet metal and such
[19:21:32] <renesis> i dont use acad for 3d
[19:22:14] <JymmmEMC> fenn: Yeah, those I've seen, even peel-and-stick too
[19:22:18] <renesis> like, i guess it does it, but i just use it for making 2d drawings
[19:28:42] <Twingy> I'd use brl-cad before qcad, but I use solid works because brl-cad doesn't even come close
[19:30:11] <JymmmEMC> jmkasunich: I was reading your cooling writeup, how did you calcualte the wattage produced in the enclosure?
[19:30:25] <jmkasunich> educated guess
[19:31:15] <JymmmEMC> jmkasunich: and the back pressure is really that significant on a 120mm "pc fan" ?
[19:31:26] <JymmmEMC> 120VAC not 12V
[19:31:45] <jmkasunich> re: wattage - PC is pretty easy, the power supply sets the absolute upper limit, most PCs use less than half the power supply rating
[19:32:08] <jmkasunich> VFDs are usually over 90% efficient, so assume 10% of spindle power is losses
[19:32:16] <JymmmEMC> jmkasunich: The PC is going to be extrnal from the enclosure for me (no room)
[19:32:17] <jmkasunich> gecko losses are in the datasheet
[19:32:53] <JymmmEMC> 2 PS's, 3(4) drives, relays
[19:33:30] <SWPadnos> the PS gives you an upper limit on the total power used by anything run from it (like relays)
[19:33:47] <SWPadnos> the 24V supply is a 100W unit, probably 80% efficient
[19:33:57] <SWPadnos> so that's an absolute maximum of 120W or so
[19:34:05] <jmkasunich> that limit may be way high tho, since some of the loads are outside the box
[19:34:16] <SWPadnos> (125 actually, but these are estimates :) )
[19:34:30] <jmkasunich> for example, the supply that runs your motors delivers most of its power to the motors which aren't in the box
[19:34:32] <JymmmEMC> 48vdc@5.5A = 264W
[19:34:34] <SWPadnos> yes - the lights for example will radiate out of the box
[19:34:46] <SWPadnos> the 24V supply isn't for the motors
[19:35:23] <JymmmEMC> but wont the drives disapate heat too?
[19:35:35] <SWPadnos> yes, but their losses are the only thing that heats the box
[19:35:44] <SWPadnos> the power delivered to the motors is outside the box
[19:35:55] <SWPadnos> is that 48VDC supply a switcher too?
[19:36:07] <jmkasunich> geckos dissipate something like 18 watts MAX, even when delivering a couple hundred watts to the motor
[19:36:22] <JymmmEMC> SWPadnos: yes
[19:37:37] <JymmmEMC> SO what you guys are saying is that there can't be more heat than what the two PS's can (potentially) provide whisch is a total of 364 Watts?
[19:37:54] <SWPadnos> if you assume 80-90% efficiency for the supply, then the worst case is ~50W from the supply, plus the 18 or so per gecko = ~100W from the motor drive system
[19:38:06] <jmkasunich> add up all the power that enters the box, and subtract all the power that leaves the box
[19:38:13] <SWPadnos> that's an absolute max upper limit, but it's also unrealiztically high
[19:38:16] <SWPadnos> -z
[19:39:25] <jmkasunich> if you are doing a stepper machine, and don't have the computer or a VFD in the box, I'd be surprised to see more than 150W, and most likely it will be under 100
[19:39:36] <JymmmEMC> The absolute values give me a baseline to work with. Now to calc the disapation from jmkasunich's writeup
[19:40:17] <owhite> hello people. I have a M100 program that gets called in my g-code. Does it matter what kind of executable it is? Is it okay if its perl?
[19:40:29] <cradek> owhite: doesn't matter
[19:40:30] <jmkasunich> I should clarify: if you are doing a stepper machine with geckos... L/R drives can dissipate a lot of power
[19:40:34] <SWPadnos> owhite, emc doesn't care
[19:40:53] <JymmmEMC> jmkasunich: They're actually PArker OEM750 drives
[19:41:05] <jmkasunich> still chopper based, right?
[19:41:07] <SWPadnos> it's Parker OEM7xx or OEM6xx drives, so should be similar to geckos, with different numbers substituted :)
[19:41:09] <SWPadnos> yes
[19:41:13] <owhite> thanks cradek, SWPadnos. One more question, where should the M100 file reside? how will emc find it?
[19:41:26] <SWPadnos> uh - in the nc_files dir?
[19:41:27] <owhite> the best place for me would be config/
[19:41:35] <owhite> oh. that makes sense.
[19:41:52] <SWPadnos> I think that's where they go. look for the sample M100 and M101 code
[19:41:58] <SWPadnos> s/code/programs/
[19:43:06] <owhite> thanks. I think they should go in the /config directories, given that my M100 is making calls to signals which are specific to the .hal files. :-)
[19:43:06] <jmkasunich> cradek: how goes the genemotor?
[19:43:22] <owhite> ...but I aint complainiin'
[19:43:37] <cradek> jmkasunich: fail
[19:43:45] <jmkasunich> bummer
[19:43:55] <SWPadnos> owhite, that makes sense to me as well, though there are also uses for external codes that may not be as specific to the machine (maybe user interface related or something)
[19:44:05] <owhite> fair enough.
[19:44:10] <cradek> jmkasunich: I made sure (again) everything is bled. still no dribble from the third port
[19:44:26] <jmkasunich> this is with the lines disconnected at the pump?
[19:44:36] <cradek> yes
[19:44:43] <cradek> one just doesn't do anything
[19:44:54] <jmkasunich> and you do see pulses of fluid at the other two ports?
[19:45:01] <JymmmEMC> jmkasunich: Any suggestions other than a car air filter (like you are using), I don't have THAT much room to play with =)
[19:45:04] <cradek> not pulses, but some fluid
[19:45:29] <SWPadnos> JymmmEMC, maybe look at some flat AC filters or something
[19:45:33] <jmkasunich> JymmmEMC: depends on the amound of dirt
[19:45:59] <jmkasunich> there are car filters that are flat as well, for example maybe 6" wide x 8" long, and pleated for a thickness of maybe 1"
[19:46:21] <jmkasunich> it really depends on how much dirt you expect - I tend to overdesign things
[19:46:23] <cradek> yeah, most are flat now
[19:46:32] <jmkasunich> you're doing wood, aren't you?
[19:46:35] <SWPadnos> you probably won't need as much cooling as jmk anyway - he's got the PC and VFD in there
[19:46:38] <JymmmEMC> 1" would be cool. Like the old carbuator filters.
[19:47:03] <SWPadnos> oh wait - I don't see the VFD
[19:47:18] <jmkasunich> SWPadnos: mine? it ain't in there yet
[19:47:29] <jmkasunich> still running the original single plase motors
[19:47:33] <SWPadnos> but the cooling is supposed to account for it?
[19:47:40] <jmkasunich> yeah
[19:47:57] <JymmmEMC> is there a way to calc the airflow thru some of these car filters?
[19:48:02] <SkinnYPuppY> B&S lawnmower filters are about 3" x 5" flat paper
[19:48:05] <jmkasunich> JymmmEMC: no
[19:48:13] <JymmmEMC> jmkasunich: k
[19:48:28] <jmkasunich> I'd go to the local autoparts store and get the biggest thing you can find that will fit in your situation
[19:48:38] <jmkasunich> the bigger you make it the less restriction you'll have
[19:48:51] <gezar> cradek: you get that thing running?
[19:48:53] <JymmmEMC> I wonder if a small (flat) furnace filter would do as well.
[19:48:59] <jmkasunich> if you are doing wood (very dusty) you will want good filtering
[19:49:05] <SWPadnos> and get those nice ones you can hose off - they're 2x the price, but you can reuse them :)
[19:49:07] <cradek> and then remember what "car" you have
[19:49:11] <jmkasunich> if you are doing metal, there isn't really that much airborne dust
[19:49:12] <cradek> gezar: nope
[19:49:12] <SWPadnos> heh
[19:49:16] <jmkasunich> my filter is probably overkill
[19:49:16] <JymmmEMC> cradek: no doubt =)
[19:50:11] <JymmmEMC> Well, I know the filter on my shopvac is 3x bigger than the one your using jmkasunich, and it gets clogged pretty quick.
[19:50:23] <JymmmEMC> Though it's a hepa filter
[19:50:32] <SWPadnos> well, the application is a little different for a vacuum cleaner
[19:50:32] <jmkasunich> I hope you won't be using your cooling system to clean up the shop
[19:50:34] <JymmmEMC> .03micro or some crap like that
[19:50:54] <JymmmEMC> Heh, no. Just the only comparision I have atm
[19:51:24] <JymmmEMC> But I'd suspect the same particles will be in the air
[19:51:24] <SWPadnos> try sticking the shop-vac nozzle in the air, and see how long it takes the filter to clog
[19:51:35] <SWPadnos> yuo'll be there a long time
[19:51:39] <SWPadnos> you
[19:51:50] <SWPadnos> how do you like those DIN relays?
[19:52:00] <SWPadnos> cute little buggers, huh?
[19:52:05] <JymmmEMC> SWPadnos: No, it's pretty clogged already.
[19:52:12] <SWPadnos> gwt a new one first
[19:52:13] <SWPadnos> get
[19:52:15] <JymmmEMC> SWPadnos: What amperage are the contacts on the tiny ones?
[19:52:24] <JymmmEMC> SWPadnos: Nah, just hose it off =)
[19:52:27] <SWPadnos> don't remember - they say on the side I think
[19:52:28] <jmkasunich> RTFL?
[19:52:39] <JymmmEMC> I just opened the box today
[19:52:44] <SWPadnos> 10A
[19:52:48] <JymmmEMC> ew
[19:53:11] <JymmmEMC> I was afraid of that. damn.
[19:53:11] <jmkasunich> ew?
[19:53:23] <JymmmEMC> 12.5A peak is what I need =(
[19:53:35] <SWPadnos> the big ones are 20
[19:53:35] <jmkasunich> what are you trying to switch?
[19:53:45] <SWPadnos> router and vacuum motors
[19:53:46] <JymmmEMC> jmkasunich: router
[19:53:54] <jmkasunich> get a small contactor
[19:54:02] <SWPadnos> I sent a couple of those as well :)
[19:54:03] <jmkasunich> relays aren't for heavy loads
[19:54:15] <SWPadnos> these are contactor-style, dual-contact relays
[19:54:21] <JymmmEMC> jmkasunich: they are contactors
[19:54:30] <jmkasunich> then why'd you call them relays
[19:54:32] <JymmmEMC> the others are MONSTERS
[19:54:36] <jmkasunich> it confuses my feeble mind
[19:54:44] <SWPadnos> I called them relays, sorry :)
[19:54:52] <jmkasunich> somehow I doubt they are monsters
[19:55:03] <SWPadnos> the others are, relative to small machines
[19:55:09] <JymmmEMC> weight at leat a lb each
[19:55:25] <jmkasunich> we have a few multi-hundred amp ones in the dumpster at work, want one?
[19:55:39] <SWPadnos> CA3SK here: http://ecatalog.squared.com/catalog/173/html/sections/21/17321013.html
[19:55:42] <SWPadnos> heh
[19:55:44] <JymmmEMC> jmkasunich: only if it comes with it's own enclosure =)
[19:55:47] <SWPadnos> shipping cost is too high ;)
[19:56:39] <jmkasunich> JymmmEMC: if you have true contactors, not relays, you might be able to use them for your router
[19:56:51] <jmkasunich> contactor (and relay) contact ratings are non-trivial to interpret
[19:57:15] <JymmmEMC> jmkasunich: the link SWPadnos provided
[19:57:28] <jmkasunich> if you are comparing the continuous rating of the contactor with the peak inrush rating of your motor, you are being _very_ conservative
[19:57:31] <SWPadnos> those are just the small ones. I'm looking for the page with the actual contactors
[19:58:14] <JymmmEMC> jmkasunich: I honestly dont know the difference in what the contact can handle.
[19:58:28] <JymmmEMC> jmkasunich: peak -vs- cont that is
[19:59:08] <jmkasunich> what is the router? 120V AC? how many HP? what is the rated (continuous) current?
[19:59:16] <JymmmEMC> looking...
[20:00:04] <jmkasunich> it seems the contactors are rated 7200VA for make, 720VA for break
[20:00:32] <JymmmEMC> 2.25 HP, 12 Amps, 8,000-25,000 RPM
[20:00:40] <jmkasunich> make shouldn't be a major issue, but break is marginal - you won't get great life
[20:00:45] <JymmmEMC> http://bosch.cpotools.com/routers/router_combo_packs/1617evspk.html
[20:01:11] <jmkasunich> oh, 12A
[20:01:20] <jmkasunich> you want something a notch bigger for that
[20:03:04] <SWPadnos> LC1D09 on this page: http://ecatalog.squared.com/catalog/174/html/sections/18/17418002.html#58350
[20:03:17] <SWPadnos> (it's actually an LP1, but that's just the DC coil)
[20:03:34] <jmkasunich> the top line in the table?
[20:03:41] <SWPadnos> hmmm. yes
[20:03:50] <jmkasunich> not gonna hack it - only rated at 1/2 HP at 120VAC single phase
[20:03:53] <SWPadnos> but those numbers are very different from what's on the side of the contactor
[20:04:20] <jmkasunich> even thought the router is in sears HP, its probably an honest HP, and a half-hp contactor isn't a good idea
[20:04:32] <JymmmEMC> SWPadnos: is that the large contactor specs?
[20:04:36] <SWPadnos> yes
[20:04:48] <SWPadnos> did I send LP1D09 or LP1D18?
[20:05:25] <jmkasunich> the D18 would probably be fine for your router
[20:06:17] <SWPadnos> hmmm.
[20:06:28] <SWPadnos> the D18 is the same size, except about 1/4 inch taller
[20:06:46] <SWPadnos> if you need those instead, I have a couple
[20:07:13] <jmkasunich> how many poles are the ones he already has?
[20:07:13] <SWPadnos> it's always funny when you see breakout boards with their 10A / 20A relays
[20:07:20] <SWPadnos> makes you wonder how long they work
[20:07:22] <SWPadnos> 3
[20:07:38] <SWPadnos> they're all 3-pole +1 aux contact
[20:07:52] <SWPadnos> hmmm - parallel the wires?
[20:08:02] <SWPadnos> s/the/3/
[20:08:03] <jmkasunich> for a single phase motor, if its hard-wired so you know which conductor is hot, you can set it up to break hot only
[20:08:23] <jmkasunich> then parallel three poles for that one conductor
[20:08:47] <jmkasunich> not quite per code, but for a personal project it will improve reliability
[20:09:20] <jmkasunich> biggest problem is at break, because one pole will be last, and it will get to break all the current
[20:10:03] <SWPadnos> hmmm. on that first page (with the CA3SK), they rate inductive loads at 35% PF - isn't that a bit conservative
[20:10:05] <jmkasunich> I've done the paralleling thing in situations where the contactor never makes or breaks under load
[20:10:21] <jmkasunich> thats not for motors
[20:10:22] <SWPadnos> especially for something that's supposed to be plugged into a household AC outlet
[20:10:33] <jmkasunich> its probably about right for contactor coils
[20:10:51] <SWPadnos> ok, they are marked separately for "heavy pilot duty"
[20:10:57] <jmkasunich> there you go
[20:11:05] <jmkasunich> pilot duty = controlling another contactor
[20:11:14] <SWPadnos> also for continuous, but well, there are a lot of specs to choose from :)
[20:11:15] <SWPadnos> yep
[20:11:34] <jmkasunich> that explains the 10:1 ratio between make and break ratings too
[20:11:41] <jmkasunich> contactors have large inrush currents
[20:11:43] <SWPadnos> right
[20:11:52] <SWPadnos> higher actuation load than holding load
[20:12:08] <jmkasunich> ka-chunk
[20:12:14] <SWPadnos> heh
[20:12:48] <SWPadnos> it is funny to be near a machine that has a big contactor
[20:12:57] <SWPadnos> when you're not expecting the very large THUNK!
[20:13:05] <jmkasunich> tell me about it
[20:13:07] <SWPadnos> heh
[20:13:14] <jmkasunich> I always jump
[20:13:15] <SWPadnos> no need, I'm sure
[20:13:46] <JymmmEMC> lp1d0910
[20:13:52] <SWPadnos> ok - the smaller ones
[20:13:59] <JymmmEMC> http://ecatalog.squared.com/catsearch.cfm?QueryText=lp1d0910&ResultCount=10&QueryTextClass=&Soptions=starts
[20:14:14] <JymmmEMC> But there is no two-letter suffix on the contactor
[20:14:32] <SWPadnos> that's on the coul - look at the blue part under the top beige part
[20:14:34] <SWPadnos> coil
[20:14:35] <ALS> cradek: deisel? ck the delivery valve is not stuck open on the pump, after sitting lease get gui and get stuck open and piston will pull the fuel back down and not reload
[20:14:40] <SWPadnos> BD means 24V DC
[20:14:41] <jmkasunich> you sure don't need the 575V part
[20:15:09] <JymmmEMC> 20A cont
[20:15:22] <JymmmEMC> SWPadnos: ah on the BD
[20:16:00] <JymmmEMC> wth it says 9A on the specs I have no clue... http://ecatalog.squared.com/fulldetail.cfm?partnumber=LP1D0910BD
[20:16:15] <jmkasunich> because 9A is the main rating
[20:16:16] <JymmmEMC> if the coil is drawing that much, no thanks =)
[20:16:35] <SWPadnos> heh - not likely ;)
[20:16:49] <SWPadnos> the 24V PS is only 4.2A anyway :P
[20:16:56] <JymmmEMC> jmkasunich: in the contact itself it says "Continous current: 20 A"
[20:16:57] <SWPadnos> or 4.5 or something
[20:17:10] <jmkasunich> JymmmEMC: I told you ratings aren't simple
[20:17:16] <jmkasunich> there are many ratings for a contactor
[20:17:19] <JymmmEMC> jmkasunich: =)
[20:17:31] <SWPadnos> picking the one that's appropriate for your load is the hard part
[20:17:34] <jmkasunich> HP ratings, which depend on the voltage and whether the motor is single or three phase
[20:17:41] <SWPadnos> once you know that, it's just a matter of looking at the number
[20:17:41] <jmkasunich> Amp ratings, inductive and resistive
[20:17:42] <JymmmEMC> I do see "I <sub>th</sub>: 25A
[20:17:50] <jmkasunich> also AC3 and AC1 ratings
[20:18:06] <jmkasunich> Ith is a thermal rating - that menas it can carry 25A continuously when closed without overheating
[20:18:09] <SWPadnos> don't forget IEC ratings
[20:18:14] <jmkasunich> it does NOT mean it can make or break 25A
[20:18:26] <jmkasunich> AC1 and AC3 are IEC ratings
[20:18:31] <SWPadnos> ah
[20:18:34] <JymmmEMC> jmkasunich: gotcha. Just passing on what I see is all =)
[20:18:45] <jmkasunich> AC1 is non-inductive, AC3 is generic three phase induction motor
[20:19:01] <jmkasunich> there are other less common ACn ratings, for different kinds of motors or applications
[20:20:44] <JymmmEMC> I hate to soudn so simple minded about this... but bugs the crap out of me when a $1.25 switch on the router itself can handle the load, yet a $50 relay/contactor can't.
[20:21:18] <jmkasunich> JymmmEMC: this is not black and white
[20:21:28] <jmkasunich> of course the $50 contactor can handle it - for a while
[20:21:55] <jmkasunich> the contactor ratings are probably based on a lifetime of at least 100,000 operations under load
[20:21:55] <SWPadnos> the router is soft-start, but not soft-stop ;)
[20:22:15] <jmkasunich> the router has a softstart? didn't know that
[20:22:28] <SWPadnos> I believe so, but cutoff isn't so soft
[20:22:34] <JymmmEMC> SWPadnos: It's still the same $1.25 though (in my simplictic mind)
[20:22:41] <jmkasunich> remember - contactor ratings are NOT based on universal (brush) motors like in a router, they are based on squirrel cage induction motors
[20:22:46] <JymmmEMC> jmkasunich: Yeah, on the soft-start.
[20:22:50] <SWPadnos> soft start helps a lot
[20:23:25] <jmkasunich> JymmmEMC: try starting and stopping the router 100,000 times using that $1.25 switch and see what happens
[20:23:32] <SWPadnos> heh
[20:23:41] <SWPadnos> see you next October ;)
[20:23:56] <jmkasunich> I suspect that after a few thousand times, the contacts will be burned and pitted, and it won't work so well
[20:24:08] <SWPadnos> oh, and alternate hands or you'll get Carpal Tunnel ;)
[20:24:29] <jmkasunich> but - are you going to switch it that many times? if not, then you can certainly get away with something that doesn't strictly meet the specs
[20:25:31] <SWPadnos> it's only breaking load that matters, due to the soft-start
[20:25:47] <SWPadnos> (I think)
[20:26:46] <jmkasunich> I really don't know what the characteristics of a universal motor are, especially one with a soft-start
[20:28:40] <jmkasunich> http://pokoj.com.pl/files/pdf/StycznikiEng_WebOpt.pdf
[20:28:44] <jmkasunich> quite educational
[20:28:56] <jmkasunich> it has listings of AC1 thru AC6a and b with explanations of what they are
[20:29:02] <SWPadnos> cool
[20:29:21] <jmkasunich> and explanations of how contact life is affected by current, etc
[20:29:43] <jmkasunich> that vendor designs for 1 million cycles at rated load
[20:30:27] <SWPadnos> hmmm. being in Poland, I wonder if the prices are lower (still ~3 Zloty / $)
[20:31:11] <SWPadnos> hmmm. I wonder if they've switched to the Euro
[20:31:28] <jmkasunich> no clue - I was interested in the technical info, not the contactors
[20:31:41] <jmkasunich> page 10 has the AC1-6 info
[20:31:50] <jmkasunich> page 20 has contact life info
[20:32:07] <SWPadnos> holy crap. the dollar is down to 2.31 PLN. that's outrageous
[20:32:41] <jmkasunich> Buy American!
[20:32:45] <SWPadnos> heh
[20:33:05] <SWPadnos> that's one advantage of a sliding dollar - now imports are getting expensive too :)
[20:34:52] <SWPadnos> hmmm. woulda universal motor be somewhere between AC-2 and AC-3? (not quite slip-ring, not quite induction)?
[20:35:11] <jmkasunich> that seems reasonable to me
[20:40:12] <JymmmEMC> Though I can't tell the contact voltage.... http://cgi.ebay.com/AEG-LS05-LS-05-MINI-POWER-RELAY-CONTACTOR-15-AMP_W0QQitemZ270174662537QQihZ017QQcategoryZ42897QQrdZ1QQssPageNameZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem
[20:40:22] <JymmmEMC> Specs http://www.calcentron.com/Pages/AEGHomePage/aeg_contactors/aeg_contactors_home.htm
[20:40:52] <JymmmEMC> sorry, the coil voltage
[20:41:28] <SWPadnos> 120VAC
[20:41:33] <jmkasunich> JymmmEMC: those are no better than what you have
[20:41:37] <JymmmEMC> k
[20:41:59] <lerman> Do any of you guys have a laser interferometer (such as Agilent or HP)?
[20:42:01] <jmkasunich> JymmmEMC: seriously, have you been paying any attention to what I'm telling you
[20:42:21] <SWPadnos> lerman, hahaha - uh, no :)
[20:42:38] <ALS> cradek: ^^ ^^ sometimes you can take a small alluminum rod and with a small hammer tap on the top of the valve seat through the hole under the line coming out of the pump, you ck and see if its stuck up by measuring each hight of the valves
[20:42:50] <JymmmEMC> lerman: If you would have asked me 15 years ago, I would have said yes.
[20:42:54] <lerman> I bought some receivers and am looking at some laser heads.
[20:43:06] <JymmmEMC> jmkasunich: I'm trying to, really.
[20:43:19] <lerman> I'm curious about faking/making the cables.
[20:43:38] <jmkasunich> just use the larger of the contactors/relays that you already have
[20:43:47] <JymmmEMC> jmkasunich: k
[20:43:50] <jmkasunich> if it fails after 10,000 operations, then replace it with something bigger
[20:43:56] <jmkasunich> odds are it won't
[20:44:17] <jmkasunich> odds are also that it will take you a long time to hit 10,000 operations, let alone 100,000 or a million
[20:44:37] <jmkasunich> this is for hobby use, right?
[20:44:46] <JymmmEMC> Just curious... when they say 10,000 operations, is a single operation make AND break, or one of each is really two operations?
[20:45:00] <jmkasunich> start and stop = one operation
[20:45:04] <JymmmEMC> k
[20:45:22] <JymmmEMC> yes, on the hobby use.
[20:45:24] <SWPadnos> even production would take a while. It's only needed at startup or toolchange
[20:45:30] <jmkasunich> right
[20:47:03] <JymmmEMC> man, I got a headache... and I don't even think it's from you guys either ;)
[20:47:12] <SWPadnos> nyah nyah :)
[20:47:29] <JymmmEMC> still getting over this last bit of cold/flu crap still I think
[20:48:03] <SWPadnos> oh - it looks like I won't be going to India ( :( ), so I'll be a bit more flexible as far as getting out there the next time
[20:48:11] <JymmmEMC> OH I got drugs right here!!!
[20:48:31] <SWPadnos> you know you're in trouble if you're too down to see the drugs ;)
[20:48:52] <JymmmEMC> they were in the laptop bag
[20:49:07] <jmkasunich> SWPadnos: I can't tell if that was a smilie or a frownie.... if it was me, and a trip to india got canceled, I'd be very happy
[20:49:11] <SWPadnos> damn - now there's a precide interferometer: http://www.canon.com/technology/canon_tech/explanation/compact_interferometer.html
[20:49:33] <SWPadnos> this one would have been pretty easy, other than the 48 hours on a plane ;)
[20:49:46] <SWPadnos> precise, that was
[20:50:39] <SWPadnos> the original schedule had us going through Surich, staying there for a day, then going to Mumbai, having a rest day, then two work days (not too hard - set up some cameras, shoot the actress, wrpa up), then a rest day, then the travel home day
[20:51:00] <SWPadnos> 2 days work over a week, all expenses paid, and a few $k on top of it - sounds good to me
[20:51:21] <SWPadnos> gah
[20:51:30] <SWPadnos> Zurich, where the heck is Surich?
[20:54:17] <JymmmEMC> SWPadnos: That Way --->
[20:54:17] <SWPadnos> oh, thanks
[20:54:17] <SWPadnos> hmmm. no, that's the back yard
[20:54:17] <SWPadnos> which is now covered in an extra inch of ice
[20:54:17] <JymmmEMC> SWPadnos: Keep going... hoping over the fences, etc
[20:54:17] <SWPadnos> ooooohhhhhh - now I get it
[20:55:49] <ALS> if someone here's from cradek tell to read back thanks
[20:56:27] <JymmmEMC> I never knew cradek was a place, I'll be damn
[20:56:43] <ALS> him
[20:57:10] <JymmmEMC> if someone here's from Canada tell to read back thanks
[20:57:21] <SWPadnos> :P
[20:58:26] <JymmmEMC> I know I botch the english lang a bit, and I had to read what he said a few times to understood what he meant, but damnnnnnnnnnnnn! LOL
[20:59:10] <SWPadnos> it seems the web brings out the similarities between "their" and "they're", among others
[20:59:31] <SWPadnos> luckily, there are a lot of people standing ready to correct those errors (usually me ;) )
[20:59:43] <JymmmEMC> whoa... format 20gb ntfs partition in 15s
[21:00:02] <SWPadnos> write mid-drive FATs, mark whole drive as empty. done
[21:00:15] <JymmmEMC> SWPadnos: Nah, vmware =)
[21:00:18] <SWPadnos> heh
[21:00:21] <jmkasunich> only when "format" means "erase FATish things, and don't touch anything else"
[21:00:24] <SWPadnos> just wait for a sync
[21:00:34] <SWPadnos> that should take some time
[21:00:40] <JymmmEMC> SWPadnos: no need, all virtual =)
[21:00:56] <SWPadnos> unless you're using actual disk space for that virtual drive ...
[21:01:05] <JymmmEMC> osx -> vmware -> xp
[21:01:12] <SWPadnos> ie, when you shut down the VM, it'll write those changes to disk
[21:01:19] <SWPadnos> (or beore, possibly)
[21:01:21] <SWPadnos> before
[21:01:58] <JymmmEMC> SWPadnos: shutdown is pretty quick actually. Though I usualyl use boot camp, yet we dont support bootcamp for users =)
[21:02:44] <SWPadnos> unless you're using a dynamically allocated VM disk, all that data should get written to the physical HD at some point
[21:03:10] <SWPadnos> (even with dynamic allocation, it's dependent on the XP format operation, which usually doesn't erase the whole disk AFAIK)
[21:03:40] <JymmmEMC> SWPadnos: I have no clue how vmware works, just know it does a nice job
[21:03:50] <SWPadnos> heh - that it does
[21:04:03] <SWPadnos> I should get it running on my big machine again, and maybe on the laptop also
[21:04:21] <SWPadnos> though apparently even big apps like Altium will run in Wine now (with sufficient prodding)
[21:04:22] <JymmmEMC> SWPadnos: Though, since macs now have intel cpu's. if there was a firewire iface to emc, HAWT DAMN!
[21:04:31] <SWPadnos> heh
[21:04:44] <JymmmEMC> fsck this paraport or USB crap
[21:04:55] <SWPadnos> I don't know if there's a similar cycle time limitation with firewire
[21:05:00] <SWPadnos> (relative to USB)
[21:05:10] <JymmmEMC> SWPadnos: 20mbps iirc
[21:05:27] <SWPadnos> the data rate is 400 Mbits/sec or 800 mbits/sec
[21:05:52] <SWPadnos> ie, 50 Mbytes or 100 Mbytes
[21:06:06] <JymmmEMC> SWPadnos: might be something to look into. since it wouldn't be limited to macs and firewire cards are cheap enough.
[21:06:21] <SWPadnos> USB is in the same realm, but the question I was voicing has to do with packet timing, not data throughput
[21:06:34] <SWPadnos> there are servo protocols that use firewire already
[21:06:36] <JymmmEMC> SWPadnos: I totally understand
[21:07:33] <JymmmEMC> SWPadnos: first link http://www.google.com/search?q=firewire+packet+timing&start=0&ie=utf-8&oe=utf-8&client=firefox&rls=org.mozilla:en-US:unofficial
[21:08:11] <JymmmEMC> SWPadnos: I was wrong, it's 30mbps, not 20mbps
[21:08:27] <SWPadnos> what is?
[21:08:52] <SWPadnos> looks like an 8 KHz clock unit, which is probably fine for most motor control cases
[21:09:32] <JymmmEMC> there we go...
[21:09:55] <JymmmEMC> When should I expect to see a beta FW iface in emc?
[21:09:56] <SWPadnos> where aer you reading numbers like 20 mbps and 30mbps? (and is that a bit or a byte?)
[21:10:04] <JymmmEMC> 3 maybe 4 hours?
[21:10:06] <SWPadnos> 2112, unless you make one sooner
[21:10:55] <JymmmEMC> come on now... FW has got to be better than all this garbage we got so far
[21:11:19] <SWPadnos> it's no better than a mesa card or equivalent
[21:11:29] <JymmmEMC> more uniniversal though.
[21:11:41] <SWPadnos> whatever that means ;)
[21:12:42] <JymmmEMC> Well, (heaven forbid) should Mesa cease to exist overnight, then where are ya?
[21:13:09] <SWPadnos> about the same place you'd be when the only vendor for firewire drives goes out of business overnight ...
[21:13:25] <SWPadnos> except that you'd still have the ability to write your own FPGA configs for the Mesa
[21:14:18] <JymmmEMC> is that really needed? Isn't there enough in the fw specs so you could do it in emc?
[21:14:18] <SWPadnos> (and there are other vendors of PCI FPGA cards, you'd just need to do a bit of work to change the PIN files for the (open-source) FPGA code
[21:14:45] <JymmmEMC> I really am just asking.
[21:14:46] <SWPadnos> you need a piece of hardware at the other end, to talk to the motor drives or motors and all the I/O
[21:14:59] <JymmmEMC> sure, just like DV do
[21:15:13] <jmkasunich> RT firewire has the same problem as RT ethernet (I suspect)
[21:15:32] <SWPadnos> yes
[21:15:35] <JymmmEMC> but couldn't it just speak DS or the other one (that eluds me atm)
[21:15:46] <SWPadnos> you can't use normal device drivers from RT code
[21:15:48] <jmkasunich> the Linux drivers (probably) aren't realtime, and there are too many chipsets to write our own drivers
[21:16:36] <JymmmEMC> Other than the firewire card drivers, is other drivers needed?
[21:16:54] <JymmmEMC> I thought a lot of that was in the specs
[21:17:16] <jmkasunich> I'm talking about the card drivers
[21:17:21] <SWPadnos> well, you need to be able to talk to the firewire controller, in addition to knowing how to talk to the end device
[21:17:22] <jmkasunich> they are almost certainly not realtime
[21:17:40] <SWPadnos> the FW card drivers are almost assuredly not realtime
[21:17:52] <SWPadnos> there amy be RT FW drivers somewhere though, like COMEDI
[21:17:56] <SWPadnos> may
[21:18:27] <JymmmEMC> just something I found on google http://lists.apple.com/archives/Firewire/2004/Oct/msg00009.html
[21:18:28] <SWPadnos> imagine what would happen when you plug in a camera though ...
[21:18:47] <JymmmEMC> or is real time thread something different?
[21:18:58] <SWPadnos> real time means different things to different people
[21:19:30] <SWPadnos> for us, it means at least 1ms cycle times, ideally with <20 us or so of jitter
[21:19:53] <SWPadnos> ideally, you'd be able to push that to a few kHz, maybe 10
[21:19:55] <JymmmEMC> SWPadnos: that link I gave mentions a lot of timign aspects over my head you might want to take a look though
[21:20:09] <SWPadnos> with similar reduction in jitter - down to a few microseconds
[21:21:10] <SWPadnos> that link doesn't seem to have a lot of useful information
[21:21:41] <SWPadnos> most Mac users (though that looked like a Linux-related post) are interested in realtime that's related to video/audio
[21:21:59] <SWPadnos> so if you can pump the data for a frame of video within 15 ms or so, then you're fine
[21:22:27] <SWPadnos> it's only if you miss that deadline that there's a problem, so a few ms of jitter isn't a problem until it goes over the deadline
[21:22:58] <SWPadnos> that's not so for us, (especially if the PC is generating PWM or step pulses - though it wouldn't be with an external device attached)
[21:23:45] <JymmmEMC> It's not that emc can't generate the needed pulses, it's the device accepting them properly, correct?
[21:24:00] <SWPadnos> remote deivce == EMC not generating step pulses
[21:24:14] <SWPadnos> otherwise there's not much point in anything other than a parallel card
[21:24:29] <JymmmEMC> well, when using a mesa card, what is generating the pulses?
[21:24:41] <SWPadnos> there is no way to make a USB/firewire device generate steps under EMC control (ie, like a parport)
[21:24:45] <SWPadnos> the mesa card would be
[21:24:58] <SWPadnos> EMC tells it the rate needed, then sits back until the next servo cycle
[21:25:18] <SWPadnos> you could do it with software steps, but that's kinda silly :)
[21:25:32] <JymmmEMC> ok, and the mesa outputs what? STEP/DIR to the driver?
[21:25:43] <SWPadnos> (also, I think the Mesa digital write routine isn't fast enough at the moment)
[21:25:44] <JymmmEMC> or CW/CCW respectively
[21:25:55] <SWPadnos> it outputs whatever you want
[21:26:07] <SWPadnos> assuming someone writes any necessary FPGA code ;)
[21:26:10] <JymmmEMC> in a servero/stepper configuration I mean
[21:26:34] <SWPadnos> you have the possibility of outputting whatever you want
[21:26:43] <JymmmEMC> you know what I mean
[21:27:00] <SWPadnos> step/dir, quadrature, up/down, clock/data, PWM, PDM, direct bridge drive ...
[21:27:07] <SWPadnos> err - well I may not know what you mean ;)
[21:27:20] <JymmmEMC> ok stepper is step/dir, what is typical of servo?
[21:27:25] <SWPadnos> PWM
[21:27:34] <SWPadnos> or "analog" - ie filtered PWM/dir
[21:28:00] <JymmmEMC> ok, so couldn't some device that takes FW for the input output one of those that you mentioned?
[21:28:21] <SWPadnos> that made no sense to me
[21:28:31] <SWPadnos> oh, not it makes sense
[21:28:41] <SWPadnos> step back a sec
[21:29:05] <JymmmEMC> I'm sitting, so just pretend I stepped back =)
[21:29:09] <SWPadnos> there are roughly 3 speeds at which stuff needs to be done for machine control
[21:29:12] <SWPadnos> ok, lean back ;)
[21:29:36] <SWPadnos> there's anothe faster rate inside the motor driver, but we'll leave that alone for now
[21:29:54] <SWPadnos> fastest rate: motor velocity signal generation
[21:30:06] <SWPadnos> that's usually analog, step/dir, or some form of PWM
[21:30:06] <JymmmEMC> k
[21:30:33] <SWPadnos> that needs to run fast, like a resolution of a couple of microseconds is good, faster is often better
[21:30:45] <SWPadnos> next fastest rate: the servo rate
[21:31:00] <SWPadnos> this is the 1ms thread in most systems, and is where trajectory planning is done
[21:31:15] <SWPadnos> ie, where are we, where should we move to, how do we get there (PID)
[21:31:58] <SWPadnos> the next level up is the interpreter and stuff, and isn't really realtime, as long as there's enough processor power to supply the lower levels with command data
[21:32:44] <SWPadnos> so when we're talking about realtime for EMC, we're talking more or less about two things, things that happen on a microsecond timescale and things that happen on a millisecond timescale
[21:32:59] <SWPadnos> (for the most part - obviously some machines will have different needs)
[21:33:04] <SWPadnos> wth me so far?
[21:33:07] <JymmmEMC> k
[21:33:24] <SWPadnos> so, PCs have little trouble with millisecond scale interrupts
[21:33:52] <SWPadnos> you could have max_latecny around 50000, and that's still only 5% of the total 1ms servo cycle
[21:34:08] <SWPadnos> not a big deal in the vast majority of cases
[21:34:30] <jmkasunich> to clarify: PCs have little trouble with millisecond scale interrupts IF they are running a RT kernel
[21:34:42] <JymmmEMC> jmkasunich: =)
[21:34:43] <SWPadnos> yes, thanks
[21:35:09] <SWPadnos> even the -RT kernel patches have little trouble with milliseconds, but those are still RT, even though they aren't RTAI/RTLinux
[21:35:32] <SWPadnos> the microsecond scale is where things get interesting, and this is why there are hardware assist devices around - the Mesa card, G-Rex, various servo cards, USC ...
[21:36:08] <SWPadnos> so, the thing is that EMC generates motor velocity commands at a 1ms rate
[21:36:37] <SWPadnos> (I'll say "for example" just this once - of course we know that can be changed - yadda yadda)
[21:36:50] <SWPadnos> now, let's look at USB
[21:37:04] <SWPadnos> USB and USB2 have a 1ms cycle time
[21:37:39] <SWPadnos> from what I've read, a packet may only go from the PC (to many devices) or to the PC (from many devices)
[21:38:08] <SWPadnos> this means that there is a 2ms effective cycle time for reading positions and then sending new velocity commands
[21:38:32] <Twingy> new version of gcam posted
[21:38:49] <SWPadnos> in practice, because the 1KHz USB rate and the 1KHz EMC rate won't be equal, this will degenerate into 4ms round-trip times soem of the time
[21:39:17] <SWPadnos> so that brings our update rate down to 250 Hz, which may not be good enough
[21:39:27] <JymmmEMC> (I am aware of the cavets of USB even from a non RT environment)
[21:39:37] <SWPadnos> looking at FireWire, I saw an 8 KHz number in there
[21:39:59] <SWPadnos> assuming the same restrictions as USB2, that may translate to a 2-4 KHz update rate, which is enough
[21:40:25] <SWPadnos> so firewire may be possible (I don't think anyone said it isn't), but there would be a lot of work to get it going
[21:40:51] <SWPadnos> as for latency, the isochronous mode of FireWire may work well
[21:41:09] <SWPadnos> but after all that, I still don't know the max jitter ofa FireWire transaction ;)
[21:41:32] <SWPadnos> oh - the actual point I was trying to make:
[21:42:32] <SWPadnos> the only thing you'd want to put at the end of a FW cable is something that either drives the motor directly, or does basically what a Mesa / USC does - PWM/step+dir/whatever your drive needs
[21:44:28] <JymmmEMC> SWPadnos: The latter is kinda what I was getting at via FW. Just connect your drives to the fw iface device and have everything within emc (driver wise) as needed
[21:44:53] <SWPadnos> "everything within emc (driver wise) as needed" is a pretty tall order though
[21:45:25] <SWPadnos> also, making the device wouldn't be a piece of cake by any means
[21:45:57] <JymmmEMC> I'm assuming a lot is in the iee 1394a specs here, and only driver really needed would be the firewire card in the PC, all other communication to the deives would be via fw spec
[21:46:15] <SWPadnos> the trouble with these interfaces is that even an isochronous stream only has a guarantee of throughput, not one for latency. it's assumed that you have a shitload of data to transmit, and you want to dribble it out at some rate
[21:46:31] <SWPadnos> um, there's a big gap there
[21:46:33] <JymmmEMC> SWPadnos: (think talking to a serial port in the old days, no driver is needed)
[21:46:39] <SWPadnos> firewire is like SCSI
[21:46:58] <SWPadnos> you have to negotiate with the controller to get a piece of the bandwidth, then with the device, etc.
[21:47:02] <JymmmEMC> iSCSI!!!!
[21:47:07] <JymmmEMC> ;)
[21:47:26] <SWPadnos> note that FW is not a point to point protocol, it's meant to be deasy-chained or start networked
[21:47:30] <SWPadnos> daisy
[21:47:35] <SWPadnos> gah - and star
[21:47:35] <JymmmEMC> SWPadnos: I'm making a big assumtion that the driver would be developed by the mfg
[21:48:00] <SWPadnos> so you have some of the same issues as USB - plug in a new device and renegotiate the whole shebang
[21:48:16] <SWPadnos> well, probably so, but as a Windows DLL
[21:48:43] <SWPadnos> with USB and firewire, there's a lot of setup to do before you can even send data to/from a device
[21:49:06] <SWPadnos> once that's accoomplished, the actaul data is up to you, and that's where a "manufacturer driver" would fit in
[21:49:30] <SWPadnos> it might provide functions like set_velocity, which make up a packet and send it to the right device
[21:49:34] <JymmmEMC> But if the setup is all via FW specs, once it was created, wouldn't it basically be unified and could be used anywhere?
[21:49:56] <JymmmEMC> emc, mach, tcnc, whatever
[21:49:57] <SWPadnos> but drivers are only useful when there's some sort of standard-ish API for software to talk to, which there isn't in this case
[21:50:16] <SWPadnos> in theory, everything works that way
[21:50:22] <JymmmEMC> So FW doesn't have a comm protocol already?
[21:50:42] <SWPadnos> what the heck do you mean? :)
[21:50:48] <SWPadnos> look at RS232
[21:51:15] <SWPadnos> everyone knows how to make a +/-12V interface, and how to send bits in the right format (8,n,1 ...)
[21:51:36] <SWPadnos> but that makes no guarantee that any old terminal program will be able to send files to any other terminal program
[21:51:50] <SWPadnos> what if one is kermit and the other uses zmodem?
[21:52:17] <SWPadnos> so the firewire protocol is like the RS232 spec that says "12V, 38400 baud, 8N1 ..."
[21:52:30] <SWPadnos> but once the connection is made, both ends need to know the language being used
[21:52:50] <JymmmEMC> well, that would be related back to the device's API wouldn't it?
[21:53:04] <JymmmEMC> and firewire just being the tin cans and string
[21:53:05] <SWPadnos> sure
[21:53:09] <SWPadnos> yep
[21:53:35] <JymmmEMC> so, couldn't the device's protocol be something standardized?
[21:53:38] <jmkasunich> but the string is a party line, and the RT messages need to be mixedin with the others
[21:54:04] <JymmmEMC> jmkasunich: I'm assuming no other FW devices are on the buss
[21:54:22] <SWPadnos> as far as I know, there's no standard "language" to talk to servo drives
[21:54:28] <JymmmEMC> dedicated FW if you will
[21:54:52] <SWPadnos> there are several standard protocols that provide the "tin cans and string" part (modbut, profinet, ethercat ...)
[21:54:57] <SWPadnos> modbus, that was
[21:55:34] <SWPadnos> but in the end, I can generically set register #101 to 300 for any modbus device (that has a register #100), but I have to know a lot about the device to know what that will do
[21:55:42] <SWPadnos> man, I need more coffee
[21:55:52] <JymmmEMC> ok, back to the step/dir, PWM, etc... would the FW device have to "buffer" those signals, or would emc be able to shove them down the FW pipe in RT?
[21:56:05] <SWPadnos> buffering and EMC don't play well
[21:56:23] <SWPadnos> the 1ms task likes to know where things are, and to be able to send commands based on that knowledgs
[21:56:25] <SWPadnos> e
[21:56:37] <JymmmEMC> (I know buffering isn't the correct verbage here, but it's what I use to describe the functionality of USC, mesa, etc)
[21:56:51] <SWPadnos> also, consider what happens when you hit the feed override - how long does it take to go into effect?
[21:56:54] <SWPadnos> sure
[21:57:28] <SWPadnos> actually, buffering is a fine idea, for systems that only output step/dir (no feedback), and which don't have any requirements for user interactivity (like FO...)
[21:57:46] <JymmmEMC> I guess what I'm basically asking is ther epotential for FW to break that 2mc paraport limitation.
[21:58:02] <JymmmEMC> 2ms
[21:58:11] <SWPadnos> 2ms isn't a parport limitation
[21:58:13] <SWPadnos> that's USB
[21:58:20] <SWPadnos> yes, there is potential for that
[21:58:26] <SWPadnos> based on the little I just read
[21:59:18] <JymmmEMC> I remember back that PCI was just a clusterfsck to try to attmpt within EMC directly, that's why I was thinking FW as it's specs are more readily available
[21:59:20] <SWPadnos> it's unlikely to be worth it though. any PC that can have a FW port added can also have a mesa card added. ethernet is a better (and less expensive) medium for communications because it's isolated
[21:59:47] <SWPadnos> PCI is fine, though it does take a little setup to use (getting access to PCI I/O regions for example)
[21:59:47] <JymmmEMC> I don't know what the RT eth issues are that jmkasunich mentioned.
[22:00:22] <SWPadnos> conceptually, RT ethernet is great. it's just all the work needed to do it that isn't so great
[22:00:44] <SWPadnos> ethernet is more or less a 100mbit isolated serial port
[22:01:02] <JymmmEMC> abiet eth far cheaper than FW. FW seems to address some timing in it's specs and can be faster than eth
[22:01:08] <SWPadnos> you just have to divvy up the time well (which is what RTNet does)
[22:01:27] <SWPadnos> bulk data speed isn't an issue
[22:02:52] <SWPadnos> even with 10 devices, each using a "smallest possible" packet in each direction, that's (crunch crunch) 100k packets / second
[22:03:05] <SWPadnos> err - 10 khz update rate with 10 devices, that is
[22:03:21] <SWPadnos> assuming each device needs a completely separate command and response packet
[22:03:53] <JymmmEMC> ok, so whats the issue(s) with RT eth device?
[22:03:58] <SWPadnos> writing the code
[22:04:04] <SWPadnos> and making the devices
[22:04:07] <SWPadnos> and writing that code
[22:04:16] <SWPadnos> and then making it all work :)
[22:04:56] <SWPadnos> some of it works already, but since none of us has an ethernet-connected device we can program (open source) for, there isn't a lot of work being done in that area
[22:04:59] <JymmmEMC> wget ieee* > SWPadnos
[22:05:06] <JymmmEMC> wget rfc* > SWPadnos
[22:05:17] <SWPadnos> wget aieee* > JymmmEMC
[22:05:26] <JymmmEMC> wget solderiron > SWPadnos
[22:05:50] <SWPadnos> oh, I have a G-Rex and even the Dynamic C development package for it
[22:06:09] <SWPadnos> but since nobody else does, why bother
[22:06:42] <SWPadnos> I do have a Mesa 4C81 which could work, but that doesn't have enough IO to be really useful
[22:07:36] <JymmmEMC> I mean, there does seem to be a market for it, isn't there?
[22:07:55] <SWPadnos> oh sure, there does seem to be
[22:07:56] <JymmmEMC> it does seem fairly straight foward, no?
[22:08:11] <JymmmEMC> not some conveluted propritary crap
[22:08:14] <SWPadnos> but most of the market is interested in dumb mode controllers - no feedback
[22:08:23] <SWPadnos> it's a real pain in the ass actually
[22:08:36] <JymmmEMC> simplisity always is
[22:08:38] <SWPadnos> for one thing, you need a second ethernet port
[22:08:40] <JymmmEMC> simplicity
[22:09:02] <JymmmEMC> on the pc? no need to be fucking surfing while cnc'ing damnit
[22:09:13] <JymmmEMC> sorry, just a pet peeve
[22:09:14] <SWPadnos> you then need RT drivers for every ethernet chip you want to use - you can't use the normal kernel drivers for the RT port
[22:09:45] <SWPadnos> you miss the point - you can't let the kernel touch the ethernet chip at all - it has to be controlled exclusively by the RT driver code
[22:10:08] <SWPadnos> so you'd need to reboot and move the cable around
[22:10:30] <SWPadnos> the reason you need a second eth port is that all traffic on the RT segment must be RT controlled traffic
[22:10:34] <JymmmEMC> lets say dedicated box, no networking
[22:10:54] <SWPadnos> you may not be able to use any switches (hubs only)
[22:11:08] <JymmmEMC> ok, I buy that
[22:11:30] <SWPadnos> switches may introduce unpredictable latencies
[22:11:50] <SWPadnos> a point-to-point connection would be best, but that doesn't work so well for multiple devices
[22:12:18] <JymmmEMC> 4p hub = 4 axis! woohoo problem solved!!!!
[22:12:34] <SWPadnos> I don't think there are any major theoretical issues with RT ethernet, it's a matter of time and energy
[22:12:40] <SWPadnos> 3 axis - PC + 3 drives ;)
[22:12:52] <SWPadnos> energy / effort, that is
[22:12:56] <SWPadnos> and motivation
[22:13:11] <JymmmEMC> there are cheap eth chips, that I know
[22:13:25] <JymmmEMC> 10Mbps should be fast enough, no?
[22:13:29] <JymmmEMC> per axis
[22:13:30] <SWPadnos> probably
[22:13:35] <SWPadnos> oh, certainly per axis
[22:13:41] <SWPadnos> probably overall
[22:14:05] <SWPadnos> that's about 1 kbyte per second (or ~600 bytes after protocol overhead)
[22:14:12] <SWPadnos> err - per millisecond
[22:14:19] <JymmmEMC> well, if using your hub idea, one eth chip controlling one asix of your choice of output (step/dir/cw/ccw/pwm, etc)
[22:14:51] <SWPadnos> EMC wouldn't care what the output type is
[22:14:54] <JymmmEMC> Heh, imagine ARP'ing your devices =)
[22:15:27] <SWPadnos> depends on the stack you implement on them, doesn't it? ;)
[22:16:00] <JymmmEMC> SWPadnos: No damnit! phyical layer or bust! no need for a protocol on time of that! LOL
[22:16:08] <JymmmEMC> s/time/top/
[22:16:40] <JymmmEMC> actually.... RS-232 over ethernet???
[22:16:45] <SWPadnos> RTNet uses raw ethernet packets, IIRC
[22:16:49] <JymmmEMC> or too shitty?
[22:17:02] <SWPadnos> too dumb
[22:17:04] <SWPadnos> :)
[22:17:05] <JymmmEMC> ah
[22:17:25] <JymmmEMC> what about the stuff that HP uses between test equip?
[22:17:30] <JymmmEMC> ieee something
[22:17:43] <SWPadnos> I think the main issue with large numbers of simple devices is that the minimum ethernet frame is 64 bytes long
[22:17:51] <SWPadnos> GPIB
[22:17:53] <SWPadnos> IEEE488 maybe?
[22:18:02] <JymmmEMC> GPIB is what i was thinking
[22:18:10] <JymmmEMC> 64bytes is a lot
[22:18:18] <SWPadnos> so when you have 6 bytes to send to a device, you waste a lot of time transmitting useless stuff
[22:18:48] <JymmmEMC> is a frame at the eth level?
[22:18:52] <SWPadnos> I'm not sure if the controllers enforce that though - that's to insure that a packet will be on the wire everywhere within a maximum allowed collision domain
[22:19:01] <SWPadnos> there are frames at every level ;)
[22:19:12] <JymmmEMC> whats at teh ethernet level?
[22:19:23] <JymmmEMC> * JymmmEMC not got ccna yet
[22:19:25] <SWPadnos> ethernet frame contains IP frame which contains TCP/UDP frame which contains data frame ...
[22:19:43] <JymmmEMC> there are other protocols other than tcp/ip tyvm
[22:20:08] <SWPadnos> yes, in those cases ethernet frame contains IP frame which contains ICMP frame (for example) ...
[22:20:12] <JymmmEMC> we dont need a routable protocol either
[22:20:48] <SWPadnos> http://en.wikipedia.org/wiki/Ethernet#Physical_layer
[22:20:58] <SWPadnos> the ethernet frams doesn't have to contain an IP frame
[22:21:00] <SWPadnos> frame
[22:21:19] <JymmmEMC> SWPadnos: Fine.... tokenring!!!
[22:21:20] <SWPadnos> but I used that example because most people have experience with IP
[22:22:01] <SWPadnos> http://en.wikipedia.org/wiki/Image:Ethernet_Type_II_Frame_format.svg
[22:22:27] <JymmmEMC> payload 45-1500 bytes
[22:22:37] <SWPadnos> 45 being the minimum
[22:22:44] <SWPadnos> err - 46
[22:22:53] <JymmmEMC> better than 64
[22:22:55] <SWPadnos> as I said, I'm not sure if the controller enforces that
[22:23:07] <SWPadnos> 46 byte payload + overhead makes a 64 byte packet
[22:23:16] <JymmmEMC> phoooey
[22:23:17] <SWPadnos> 14 + 46 + 4 = 64
[22:23:29] <JymmmEMC> SWPadnos: stop doing the dman math =)
[22:23:53] <SWPadnos> that's only needed if you want to make max-sized networks: 100m cable + hub + 5m interconnect + hub + 100m cable
[22:24:09] <JymmmEMC> SWPadnos: MAYBE... use the eth type for < 46 bytes
[22:24:16] <SWPadnos> if you have smaller collision domains, you could get away with smaller packets (if the controllers allow the small frames)
[22:24:28] <SWPadnos> there are no eth types for <46 byte payloads
[22:25:13] <SWPadnos> that 512-bit packet size is part of the physical protocol, to allow for large cable runs
[22:25:30] <JymmmEMC> SWPadnos: no no I mena use the eth type bytes as data for anything < 46 bytes
[22:25:35] <SWPadnos> but it may be possible to use smaller packets if you can guarantee that the cables will be shorter
[22:26:05] <SWPadnos> you're missing the point. the ethernet physical layer spec *REQUIRES* that you send 64 bytes per packet. end of story
[22:26:12] <JymmmEMC> ah
[22:26:16] <SWPadnos> what you call them is up to you ;)
[22:26:49] <SWPadnos> with smarter controller chips, the CPU doesn't have to do as much work, but it may also not have much flexibility in doing out-of-spec communications
[22:27:32] <SWPadnos> like 30-byte packets (18 bytes overhead + 12 bytes data, for example)
[22:28:20] <JymmmEMC> well, the big overhead is tha MAC addresses
[22:28:26] <SWPadnos> yep
[22:28:27] <JymmmEMC> s/tha/the/
[22:28:32] <SWPadnos> and those are pretty much required
[22:28:55] <JymmmEMC> the last three octets of each at least, not so much the firtst 3
[22:29:06] <JymmmEMC> in a closed system
[22:29:29] <SWPadnos> sure - there's no guarantee that you'll get different numbers in the low 3
[22:29:39] <SWPadnos> you need all 6 to guarantee uniqueness
[22:30:53] <JymmmEMC> it would be easy enought to check to make sure initially, then go from there for better timing
[22:31:25] <SWPadnos> even with 512-bit packets, 10mbit ethernet gives you 20k packets per second
[22:31:48] <JymmmEMC> is that a good thing?
[22:31:52] <SWPadnos> that's not a real limitation
[22:32:07] <SWPadnos> at a 1ms servo cycle, that lets you send/receive 20 packets per cycle
[22:32:28] <JymmmEMC> is that a good or bad thing?
[22:34:19] <JymmmEMC> 20 pkts @ 16000 bytes, seems like a lot to me (good ting)
[22:34:26] <JymmmEMC> 1500 bytes
[22:38:10] <SWPadnos> um - you couldn't get 20 150--byte packets through
[22:38:14] <SWPadnos> 1500-byte
[22:38:46] <SWPadnos> I'm also assuming that the normal turnaround time specs are ignored, since there's RT control over transmissions
[23:24:46] <lerman_> lerman_ is now known as lerman