Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Tue, 15 Sep 2009 20:24:16 -0500, you wrote: On Tue, 2009-09-15 at 11:06 -0400, Dave wrote: IMO you'd want it to be no more than a pulse wide or the threading may start at any of the pulses that the index spans. Strange behaviour? - It should start on either the rising or falling edge, if it starts anywhere else it needs fixing. Steve Blackmore -- -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Tue, 15 Sep 2009 20:24:16 -0500, you wrote: On Tue, 2009-09-15 at 11:06 -0400, Dave wrote: IMO you'd want it to be no more than a pulse wide or the threading may start at any of the pulses that the index spans. Strange behaviour? - It should start on either the rising or falling edge, if it starts anywhere else it needs fixing. This whole thread is about using the SOFTWARE enocder counter (a HAL component) for the spindle position. It is software sampling of the encoder signals, so the rising edge would be detected at the first sample where index was noticed to be true. But, of course, if the sample rate was slower than the quadrature count rate, the encoder counter would not be able to reliably count position anyway! So, stretching the index pulse wider than one encoder count would not actually help anything, unless you were wanting to just sense the index pulse and ignore the quadrature count. All in all, I think the whole exercise is a big mistake. If you want to use the software encoder counter, you need a low resolution encoder, maybe as low as 25 cycles/rev, or 100 quadrature counts/rev. At 1000 RPM or 16.67 RPS, that would give 1667 counts/second, plenty safe for software counting. I would think this would still give perfectly smooth following of the axis. If you insist on a higher resolution encoder, then you should be using a hardware encoder counter. Any possibility of accidentally running the spindle at a speed where the software counter loses track will eventually occur and bite you! Jon -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
I don't know how many have seen this but it really shows how flexable emc2 is. This is rigid tapping through the printer port. (and it is just cool) He is using a 360ppr encoder. http://www.youtube.com/watch?v=C740zS9R9kk You can read about it here. http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Pjm sam Jon Elson wrote: Steve Blackmore wrote: On Tue, 15 Sep 2009 20:24:16 -0500, you wrote: On Tue, 2009-09-15 at 11:06 -0400, Dave wrote: IMO you'd want it to be no more than a pulse wide or the threading may start at any of the pulses that the index spans. Strange behaviour? - It should start on either the rising or falling edge, if it starts anywhere else it needs fixing. This whole thread is about using the SOFTWARE enocder counter (a HAL component) for the spindle position. It is software sampling of the encoder signals, so the rising edge would be detected at the first sample where index was noticed to be true. But, of course, if the sample rate was slower than the quadrature count rate, the encoder counter would not be able to reliably count position anyway! So, stretching the index pulse wider than one encoder count would not actually help anything, unless you were wanting to just sense the index pulse and ignore the quadrature count. All in all, I think the whole exercise is a big mistake. If you want to use the software encoder counter, you need a low resolution encoder, maybe as low as 25 cycles/rev, or 100 quadrature counts/rev. At 1000 RPM or 16.67 RPS, that would give 1667 counts/second, plenty safe for software counting. I would think this would still give perfectly smooth following of the axis. If you insist on a higher resolution encoder, then you should be using a hardware encoder counter. Any possibility of accidentally running the spindle at a speed where the software counter loses track will eventually occur and bite you! Jon -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Wed, 16 Sep 2009 12:16:02 -0500, you wrote: Steve Blackmore wrote: On Tue, 15 Sep 2009 20:24:16 -0500, you wrote: On Tue, 2009-09-15 at 11:06 -0400, Dave wrote: IMO you'd want it to be no more than a pulse wide or the threading may start at any of the pulses that the index spans. Strange behaviour? - It should start on either the rising or falling edge, if it starts anywhere else it needs fixing. This whole thread is about using the SOFTWARE enocder counter (a HAL component) for the spindle position. Is it? I started the thread :) All I'm personally interested in is threading accurately. As I understand it, it waits for an index pulse before starting a threading pass - I know that to be true, as disconnecting the index pulse - it waits forever on a G33. Then information becomes woolly - I guess it uses the quadrature count to get an accurate speed and adjusts the Z feed accordingly?? My 3 phase VFD driven spindle isn't capable of behaving like a servo, so spindle positioning is unnecessary for me. It is software sampling of the encoder signals, so the rising edge would be detected at the first sample where index was noticed to be true. But, of course, if the sample rate was slower than the quadrature count rate, the encoder counter would not be able to reliably count position anyway! So, stretching the index pulse wider than one encoder count would not actually help anything, unless you were wanting to just sense the index pulse and ignore the quadrature count. Not if the above is true? All in all, I think the whole exercise is a big mistake. If you want to use the software encoder counter, you need a low resolution encoder, maybe as low as 25 cycles/rev, or 100 quadrature counts/rev. 125 count (500 quadrature counts/rev) works fine here via parallel port. Steve Blackmore -- -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Wed, 16 Sep 2009 12:16:02 -0500, you wrote: This whole thread is about using the SOFTWARE enocder counter (a HAL component) for the spindle position. Is it? I started the thread :) Well, I thought that was the original problem, that the software encoder counter couldn't keep up with a moderately high resolution encoder on the spindle. All I'm personally interested in is threading accurately. As I understand it, it waits for an index pulse before starting a threading pass - I know that to be true, as disconnecting the index pulse - it waits forever on a G33. Then information becomes woolly - I guess it uses the quadrature count to get an accurate speed and adjusts the Z feed accordingly?? My 3 phase VFD driven spindle isn't capable of behaving like a servo, so spindle positioning is unnecessary for me. Yes, but EMC2 by default expects a 3-channel encoder on the spindle to accurately slice up the rotation and synchronize the Z feed. Without the quadrature counts, it can only extimate velocity once per revolution, and the velocity estimate may take a long time to settle after and disturbance. Also, without the quadrature signals, it is impossible to tell spindle direction, so rigid tapping is impossible. 125 count (500 quadrature counts/rev) works fine here via parallel port. Depending on the BASE_THREAD interval and the maximum spindle RPM, you can get by. At 3000 RPM, you'd have 50 * 500 = 25,000 counts/second. If your BASE_THREAD was 40,000 (40 us) you'd be right on the edge. If your spindle never goes that fast, or your BASE_THREAD is faster, then you are OK. I just prefer to have LOTS of headroom on the encoder counter. Jon -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Tue, 2009-09-15 at 11:06 -0400, Dave wrote: Chris Radek wrote: On Mon, Sep 14, 2009 at 07:12:48PM -0400, Dave wrote: Will the EMC2 engine just wait on a threading cycle until the index pulse is seen, and once it is seen, start the cycle? Yes Good, so if my spindle is going too fast for the PC to pickup the index pulse each rev it might have to wait for a few revs before it picks it up I guess... If that becomes an issue (waiting) and I put a pulse stretcher on the index pulse and the stretcher makes the pulse longer than the other encoder pulses at the rpm the spindle is running will that be a problem? IMO you'd want it to be no more than a pulse wide or the threading may start at any of the pulses that the index spans. HTH Rayh -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Hi Ray, Guys The US digital encoder edivide box passes the index pulse straight through. I have an encoder on the spindle of my lathe but I am not sure what the resolution is - I'm guessing it is 2500 PPR just like the feed axes.That makes for a pretty short index pulse. Will the EMC2 engine just wait on a threading cycle until the index pulse is seen, and once it is seen, start the cycle? Thanks, Dave Ray Henry wrote: You might have a look at http://www.usdigital.com/products/interfaces/encoder/converters/edivide/ Something like this would allow you to experiment with speed vs resolution and still keep the encoder you've got on there. On Sun, 2009-08-16 at 10:51 +0100, Steve Blackmore wrote: Hi Guys, what's a realistic number of PPR for a lathe spindle encoder via a parallel port in EMC. Spindle is capable of 3500 rpm. My home made encoder had 90, but I've altered the drive system and fitted a 1024 PPR encoder with index. Output is via differential line drivers. I've changed the scale factor but it starts loosing pulses at 600 rpm or so?? -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Mon, Sep 14, 2009 at 07:12:48PM -0400, Dave wrote: Will the EMC2 engine just wait on a threading cycle until the index pulse is seen, and once it is seen, start the cycle? Yes -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Thu, 20 Aug 2009 20:58:41 -0500, you wrote: Steve Blackmore wrote: One reason it's far too slow is the totally unrealistic base period. 62500 is way too slow, reading the integrator manual, it probably should be much nearer 25000. It depends on the computer. If it is just a slow CPU, or has a bad jitter problem due to some hardware/software condition, then this may be as good as it can do. You then have the choice to fix the jitter problem, if possible, upgrade the CPU or the whole machine, or go to a hardware encoder counter. Jon - you must have missed this bit from an earlier post. The 62500 figure came from stepconf. Worst latency I've managed to get doing several things at once and running a GL screensaver in a window is 12uS. Pulse diagram for drives shows a 1uS rise and fall time and a minimum duration of 2.5uS, direction must lead the rise by 2.5uS or greater. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Thu, 20 Aug 2009 20:58:41 -0500, you wrote: Steve Blackmore wrote: One reason it's far too slow is the totally unrealistic base period. 62500 is way too slow, reading the integrator manual, it probably should be much nearer 25000. It depends on the computer. If it is just a slow CPU, or has a bad jitter problem due to some hardware/software condition, then this may be as good as it can do. You then have the choice to fix the jitter problem, if possible, upgrade the CPU or the whole machine, or go to a hardware encoder counter. Jon - you must have missed this bit from an earlier post. The 62500 figure came from stepconf. What version of EMC2 are you using? I could swear that I added code to stepconf to take the spindle speed/resolution into account when calculating the base period. - Steve -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Fri, 2009-08-21 at 07:41 -0400, Stephen Wille Padnos wrote: I could swear that I added code to stepconf to take the spindle speed/resolution into account when calculating the base period. - Steve IMO this thread appears to be a case of attempting to pass the buck. I can say, having written the first attempt at a configuration system, that I really appreciate the effort that you folk have put into this part of it. Each attempt to apply the configuration system to something for which it was not exactly written will lead to some frustration and to new opportunities to expand the code base. What the f32^% s*^ you mean stepconf won't configure my dumpster 386 mobo to run my 12 axis SCARA! What the hell good is this stuff anyway! Rayh -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Friday 21 August 2009, Ray Henry wrote: On Fri, 2009-08-21 at 07:41 -0400, Stephen Wille Padnos wrote: I could swear that I added code to stepconf to take the spindle speed/resolution into account when calculating the base period. - Steve IMO this thread appears to be a case of attempting to pass the buck. I can say, having written the first attempt at a configuration system, that I really appreciate the effort that you folk have put into this part of it. Each attempt to apply the configuration system to something for which it was not exactly written will lead to some frustration and to new opportunities to expand the code base. What the f32^% s*^ you mean stepconf won't configure my dumpster 386 mobo to run my 12 axis SCARA! What the hell good is this stuff anyway! Rayh I have got to say it: ROTFLMAO! ;-) Love it. -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. https://www.nrahq.org/nrabonus/accept-membership.asp Peace cannot be kept by force; it can only be achieved by understanding. -- Albert Einstein -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: Jon - you must have missed this bit from an earlier post. The 62500 figure came from stepconf. It is supposed to be derived from measurements made on the specific computer. I don't ise stepconf, so I'm not familiar with how it does that calculation. Worst latency I've managed to get doing several things at once and running a GL screensaver in a window is 12uS. Pulse diagram for drives shows a 1uS rise and fall time and a minimum duration of 2.5uS, direction must lead the rise by 2.5uS or greater. That sounds like you could go to a much faster dispatch rate. I'd think maybe 25000 would be a good place to start, just make sure there is enough CPU left for the GUI, etc. Jon -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Fri, 21 Aug 2009 07:41:34 -0400, you wrote: What version of EMC2 are you using? 2.3.2 I could swear that I added code to stepconf to take the spindle speed/resolution into account when calculating the base period. You may have, Was done nearly two years ago, I only recall it asking me what type of drives and the latency number. I had to add the spindle encoder information manually to the hal file and have not ran stepconf again since, I don't want my hal files overwriting ;) Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Friday 21 August 2009, Peter C. Wallace wrote: OK got it done and it fits in XC9572 we have on little CPLD board but I wont be able to test it until Monday 1. Input digital filter ok 15 count filter on a,b,index 2. Quadrature decoder (quadrature to up/down) ok 3. Up down modulo N counter (for divide by N) ok has 8 selectable DIVIDE_RATIOS via three input signals (jumpers on CPLD bd) 4. 2 bit up/down counter ok 5. 2 bit binary -- quadrature encoder ok 6. Optional index stretcher Works a little strange but should be ok, basically index out is set by incoming (filtered) index and cleared when DIVIDE_RATIO input encoder counts have occured (either up or down or a mix) As long as only one edge is used you will always get a index signal with a minimum width of one (divided) count That sounds almost exactly like what I would need to control the spindles on both my little lathe, and on the micro-mill. Do you have a target price for the completed unit? Question for all of the board makers here though. I need an opto assembly I can use with an encoder wheel I made and put on the lathe. This wheel was made with that bit of python code on the wiki, but with the count cut in half the hole circles scaled down to fit on the back end of the spindle in a 7x12, so the OD is now 2. 3, all done with a 1/16 mill in a sheet of hard alu that is about 16 gauge. The holes should be very slightly oblong, but are not visibly oval to my eye. I just put a copy of 'genes-encoder.ngc' on my web page if someone wants to grab it. I didn't change any credits, so that is all intact. Do any of you have either the whole assembly, or the board and a BOM to make it? Or even an nc file to make the board would be nice as I could tweek the interruptor locations for a customized really good fit. Thanks everybody. I even think we have some CPLD bds we never used that I can send over for shipping cost. Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. --- --- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. https://www.nrahq.org/nrabonus/accept-membership.asp Personally, I like to defiantly split my infinitives. :-) -- Larry Wall in 199708271551.iaa10...@wall.org -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Fri, 21 Aug 2009, Gene Heskett wrote: Date: Fri, 21 Aug 2009 21:06:16 -0400 From: Gene Heskett gene.hesk...@gmail.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Realistic spindle encoder count for parallel port? On Friday 21 August 2009, Peter C. Wallace wrote: OK got it done and it fits in XC9572 we have on little CPLD board but I wont be able to test it until Monday 1. Input digital filter ok 15 count filter on a,b,index 2. Quadrature decoder (quadrature to up/down) ok 3. Up down modulo N counter (for divide by N) ok has 8 selectable DIVIDE_RATIOS via three input signals (jumpers on CPLD bd) 4. 2 bit up/down counter ok 5. 2 bit binary -- quadrature encoder ok 6. Optional index stretcher Works a little strange but should be ok, basically index out is set by incoming (filtered) index and cleared when DIVIDE_RATIO input encoder counts have occured (either up or down or a mix) As long as only one edge is used you will always get a index signal with a minimum width of one (divided) count That sounds almost exactly like what I would need to control the spindles on both my little lathe, and on the micro-mill. Do you have a target price for the completed unit? I have bare CPLD circuit cards that I can send out for shipping cost, the CPLD is about ~2.00 its in a 44 lead PLCC. I could make preprogrammed version if anyone wants just chips or just post the source if anyone wants to hack it. The source is basically just bits and pieces copy-pasted from the HostMot2 encoder counter with a few added wigglers and twirlers. for a standalone chip version I'd add a ring or R/C oscillator so it does not need a separate clock I think I only have one assembled CPLD card An I promised that to Steve B Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Fri, 21 Aug 2009, Gene Heskett wrote: for a standalone chip version I'd add a ring or R/C oscillator so it does not need a separate clock Is there room in the cpld for that? Yes,lots of room left. Currently design uses 48 of 72 cells and could be squeezed into 36 (for $1.00 part if needed) RC osc is only a few cells but current PCB has a separate XTAL osc and RC osc (with 74HC14) So I'd need a new PCB for a builtin RC osc. Ring osc needs no pins but has less predictable frequency Design is fairly de-luxe: 15 count input filters, 8 selectable division ratios (1 to 255 range) selectable index edge polarity. Lots of squeezing possible, but I just did it in the simplest fastest way by copy+paste. I think I only have one assembled CPLD card An I promised that to Steve B And how much trouble to assemble it, considering I have had a soldering iron in hand most of the last 60 years? Used to the fine point in an XYtronic bench iron, thermally controlled of course. Should not be too hard, no fine pitch parts, smallest is 0805 resistors and capacitors, most parts could be dropped (theres a selectable frequency RC osc, a push button with debounce, a Xtal osc can (8pin half size) 4 LEDS, jtag connector, 2 26 pin I/O connectors etc With existing filter max encoder count rate is ~1/8 FOSC (FOSC up to 50 MHz or so) If you make it standalone except for 5V and ground, I want two. Name the ransom I'll have my bank send a check. :-) CPLD is 3.3V power but 5V tolerant I/O. Seems to run fine on 2 AA cells or 5V with two diode drops... Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. --- --- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. https://www.nrahq.org/nrabonus/accept-membership.asp There are no threads in a.b.p.erotica, so there's no gain in using a threaded news reader. (Unknown source) -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
You basicly only care about the index before you start the synchronized movement. It will sit there, and wait for the index. If it misses one, it will grab the next one (or at least the one it sees). Each index will still constrain to the same spindle orientation, so the thread will not be affected by this. (of course the above is only valid if you're not missing any A/B counts). Once the synchronized movement is started it will be synchronized to the A/B counts. Regards, Alex On Wed, 19 Aug 2009 22:30:10 -0500, you wrote: On Wed, Aug 19, 2009 at 10:11:19PM -0500, Jon Elson wrote: you could put in a one-shot chip to stretch the index pulse I said it once already but I don't think everyone caught it: on a spindle encoder used for threading and tapping, it doesn't matter the slightest bit if you miss the index sometimes. How many is sometimes? You certainly must not stretch it longer than one count, whatever you do. You would make the cure worse than the problem. Why - does it read on both rising and falling edge? Steve Blackmore -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Thu, Aug 20, 2009 at 12:12:24AM -0500, Jon Elson wrote: So, fixing the index pulse to reliably sense that, and completely forgetting the quadrature counting is the only thing that would work. He would then only use the index pulse, once per rev. I thought we were talking about dividing down the quadrature to a lower rate. I have done this with Jeff's code, posted earlier. When we did it, we didn't worry about stretching index. It worked fine, because like Alex explains, the only problem with missing some is the spindle will make an extra turn or two before the threading or tapping pass starts. If you are doing one pulse per rev, you sure can't miss any of them, and in this case you are right - I guess you should stretch them. (I don't recommend any of this. Getting a suitable encoder or suitable hardware to read the existing one is so much better.) Chris -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Wed, 19 Aug 2009 22:30:10 -0500, you wrote: On Wed, Aug 19, 2009 at 10:11:19PM -0500, Jon Elson wrote: you could put in a one-shot chip to stretch the index pulse I said it once already but I don't think everyone caught it: on a spindle encoder used for threading and tapping, it doesn't matter the slightest bit if you miss the index sometimes. How many is sometimes? You certainly must not stretch it longer than one count, whatever you do. You would make the cure worse than the problem. Why - does it read on both rising and falling edge? No, it would detect the index true condition whenever it sampled it. There is no edge detection in software, it just samples it until it sees that the bit is true. So, if the sampling is too slow, there will be a jitter that could be as much as one sampling period. At 16 KHz, my guess is that this is not going to cause a huge error in threading at any sane threading RPM. An error of a whole degree probably won't make much of a difference on a typical lathe, this error would be expected to be less than that. Jon -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Chris Radek wrote: (I don't recommend any of this. Getting a suitable encoder or suitable hardware to read the existing one is so much better.) Yes, a slight fudging of the encoder signals to keep within software range might be OK, but the extreme case presented by the OP is so FAR away that it seems like one of those will never work situations. If I remember the numbers right, he is about 4.44 times to slow to track the quadrature counter at 1000 RPM. His reading of losing track at ~200 RPM also indicates that is the right figure. Some people might be OK with threading at 200 RPM, but once you have CNC, there's no need to restrict yourself to that. Either a hardware encoder counter or a MUCH lower-resolution encoder is the solution. (As a seller of hardware encoder counters, I may be biased as to the correct solution to this problem...) Jon -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Thu, 20 Aug 2009 12:00:45 -0500, you wrote: Chris Radek wrote: (I don't recommend any of this. Getting a suitable encoder or suitable hardware to read the existing one is so much better.) Yes, a slight fudging of the encoder signals to keep within software range might be OK, but the extreme case presented by the OP is so FAR away that it seems like one of those will never work situations. If I remember the numbers right, he is about 4.44 times to slow to track the quadrature counter at 1000 RPM. His reading of losing track at ~200 RPM also indicates that is the right figure. Some people might be OK with threading at 200 RPM, but once you have CNC, there's no need to restrict yourself to that. One reason it's far too slow is the totally unrealistic base period. 62500 is way too slow, reading the integrator manual, it probably should be much nearer 25000. Either a hardware encoder counter or a MUCH lower-resolution encoder is the solution. (As a seller of hardware encoder counters, I may be biased as to the correct solution to this problem...) I've the 500 PPR Stegmann and a Heidenhain 125 ppr to try, unfortunately the 125 is a sinusoidal encoder, maybe the line drivers can sort that, I'll find out at the weekend. As for dividing encoder counts, it's a perfectly valid solution. There are several commercial dividers, the US Digital one pointed out here, being by far the cheapest. Stegmann even make an encoder with a pulse divider built in (DRS61 series 1-8192 PPR). Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: One reason it's far too slow is the totally unrealistic base period. 62500 is way too slow, reading the integrator manual, it probably should be much nearer 25000. It depends on the computer. If it is just a slow CPU, or has a bad jitter problem due to some hardware/software condition, then this may be as good as it can do. You then have the choice to fix the jitter problem, if possible, upgrade the CPU or the whole machine, or go to a hardware encoder counter. Jon -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Tue, 18 Aug 2009 22:16:48 +0100, you wrote: I'm not happy with the Chinese 1024 pulse encoder, but I've also got an unused Stegmann DG60L 500 pulse per rev encoder I'm going to test. Looking at the docs that too only outputs a single quadrature count index pulse, but it's much better quality and I'm hoping the signals out from it are cleaner. Just tried something with a very surprising result. PC is dual boot with Windows XP, ran Mach3 at 35kHz Kernel speed and it's capable of seeing the index pulse and giving an accurate rpm reading to 1000 rpm! I find it odd that Mach can use it but EMC can't above 200 rpm? Any ideas? It's probably related to the fact that you are running EMC2 at the equivalent of a 16 kHz kernel. (unless you changed your base period from 62500) - Steve [snip] -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Tue, 18 Aug 2009 22:16:48 +0100, you wrote: I'm not happy with the Chinese 1024 pulse encoder, but I've also got an unused Stegmann DG60L 500 pulse per rev encoder I'm going to test. Looking at the docs that too only outputs a single quadrature count index pulse, but it's much better quality and I'm hoping the signals out from it are cleaner. Just tried something with a very surprising result. PC is dual boot with Windows XP, ran Mach3 at 35kHz Kernel speed and it's capable of seeing the index pulse and giving an accurate rpm reading to 1000 rpm! I find it odd that Mach can use it but EMC can't above 200 rpm? Any ideas? It's probably related to the fact that you are running EMC2 at the equivalent of a 16 kHz kernel. (unless you changed your base period from 62500) - Steve [snip] -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Wed, 19 Aug 2009 16:57:43 -0400, you wrote: PC is dual boot with Windows XP, ran Mach3 at 35kHz Kernel speed and it's capable of seeing the index pulse and giving an accurate rpm reading to 1000 rpm! I find it odd that Mach can use it but EMC can't above 200 rpm? Any ideas? It's probably related to the fact that you are running EMC2 at the equivalent of a 16 kHz kernel. (unless you changed your base period from 62500) If it's approx half the Mach kernel value, I'd expect it to be able to see nearer 500 rpm, not just 200? Worst latency I've managed to get doing several things at once and running a GL screensaver in a window is 12uS. Pulse diagram for drives shows a 1uS rise and fall time and a minimum duration of 2.5uS, direction must lead the rise by 2.5uS or greater. I'll try dropping the base period some after I've fitted the other encoder and repeat the test. The 62500 figure came from stepconf. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: Just tried something with a very surprising result. PC is dual boot with Windows XP, ran Mach3 at 35kHz Kernel speed and it's capable of seeing the index pulse and giving an accurate rpm reading to 1000 rpm! I find it odd that Mach can use it but EMC can't above 200 rpm? Any ideas? Mach's dispatch rate can go a lot higher than EMC's, on the same hardware, due to the way Art Fenerty built his ring zero driver, it runs MUCH closer to the core of the CPU than EMC's rtai kernel modules. He saves very little of the system status to enter his interrupt service routine, we have to save a LOT of status for a formal context switch. We can do a lot more things, and do them in a lot more flexible manner, but with all that flexibility comes a reduction of performance (raw interrupt service rate). Really, if you are coming close to the limit, you ought to be using some kind of hardware assist for this. At the absolute bottom, you could put in a one-shot chip to stretch the index pulse to be at least twice your sample rate, than you should never miss a pulse. This could be a 74HC123 and one resistor, one capacitor. Jon -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Wed, 19 Aug 2009 16:57:43 -0400, you wrote: PC is dual boot with Windows XP, ran Mach3 at 35kHz Kernel speed and it's capable of seeing the index pulse and giving an accurate rpm reading to 1000 rpm! I find it odd that Mach can use it but EMC can't above 200 rpm? Any ideas? It's probably related to the fact that you are running EMC2 at the equivalent of a 16 kHz kernel. (unless you changed your base period from 62500) If it's approx half the Mach kernel value, I'd expect it to be able to see nearer 500 rpm, not just 200? Art has a LOT of trickery in his driver. I'll bet he checks for the index pulse both at the beginning and the END of his driver, doubling the likelihood of catching a short pulse. Jon Worst latency I've managed to get doing several things at once and running a GL screensaver in a window is 12uS. Pulse diagram for drives shows a 1uS rise and fall time and a minimum duration of 2.5uS, direction must lead the rise by 2.5uS or greater. I'll try dropping the base period some after I've fitted the other encoder and repeat the test. The 62500 figure came from stepconf. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Wed, Aug 19, 2009 at 10:11:19PM -0500, Jon Elson wrote: you could put in a one-shot chip to stretch the index pulse I said it once already but I don't think everyone caught it: on a spindle encoder used for threading and tapping, it doesn't matter the slightest bit if you miss the index sometimes. You certainly must not stretch it longer than one count, whatever you do. You would make the cure worse than the problem. Chris -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Chris Radek wrote: On Wed, Aug 19, 2009 at 10:11:19PM -0500, Jon Elson wrote: you could put in a one-shot chip to stretch the index pulse I said it once already but I don't think everyone caught it: on a spindle encoder used for threading and tapping, it doesn't matter the slightest bit if you miss the index sometimes. You certainly must not stretch it longer than one count, whatever you do. You would make the cure worse than the problem. Well, if somebody has a 1000 cycle/rev encoder on the spindle, and is using a PC that can only handle a 16 KHz base thread, then he has a severe mismatch already. Most lower-cost encoders have an index that is a couple counts wide, and not usually gated on one of the quadrature tracks. Gated index is a feature of some of the higher-priced encoders. With a 1000 cycle/rev encoder giving 4000 quadrature counts/rev, a jitter of a couple counts is not going to make much difference, amounting to a few tenths of a degree at most. In this particularly horrible case, at 1000 RPM he is getting 4 million counts/minute = 7 counts/second. With a base thread of 16 ms, he can only pick up one in 4 quadrature counts, so he is totally sunk. So, fixing the index pulse to reliably sense that, and completely forgetting the quadrature counting is the only thing that would work. He would then only use the index pulse, once per rev. Not a very good solution at all. Might as well run Mach in that case. Jon -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Mon, 17 Aug 2009 22:11:34 -0400, you wrote: Another approach to quadrature dividing: http://emergent.unpy.net/projects/01149271333 Needs a Pluto_P board, again too expensive over here. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Another approach to quadrature dividing: http://emergent.unpy.net/projects/01149271333 Needs a Pluto_P board, again too expensive over here. No it doesn't. It's supposed to run on an AtTiny. The Pluto-P update is just for a better version. You can also read about http://emergent.unpy.net/projects/01149348342 Regards, Alex -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Needs a Pluto_P board, again too expensive over here. The shipping for Europe for a Pluto_P is 9.90 EUR. I don't think that's _that_ excessive... Granted the total cost is 63.90 EUR delivered vs. $69.90, but that's the usual rate over the US prices anyways. Regards, Alex -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Hi Steve, Yep - only for threading, but in counter mode can EMC still make corrections for spindle speed variations? Yes. I am not sure if you can thread with the spindle in reverse using counter mode though. Hopefully this list allows attachments. This circuit uses a 4024 or 74CHT4024 counter. You can get them from any of the usual suspects such as RS, Rapid etc. You may well get away without R1 and C1 as they are just noise filtering. It depends on how much noise there is on your machine. The input is one line from either the A or B channel of the encoder. Actually I have just had a thought - you will probably also need to stretch the index pulse from the encoder. It is likely to be very short and at higher speeds EMC won't reliably detect it. Here is an example of a pulse stretcher circuit though you would have to change the values to suit your setup http://www.electronics-lab.com/articles/basics/components/555mono.htm Les inline: 4024.gif-- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Mon, 17 Aug 2009 22:11:34 -0400, you wrote: Another approach to quadrature dividing: http://emergent.unpy.net/projects/01149271333 Needs a Pluto_P board, again too expensive over here. Huh? That posting is about dividing quadrature, not Pluto. Actually, I think I linked to the posting that came immediately before the one I really wanted. Look at http://emergent.unpy.net/projects/01149348342 There is a schematic, board layout, and source code for a very tiny quadrature divider. John Kasunich -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
John Kasunich wrote: Steve Blackmore wrote: On Mon, 17 Aug 2009 22:11:34 -0400, you wrote: Another approach to quadrature dividing: http://emergent.unpy.net/projects/01149271333 Needs a Pluto_P board, again too expensive over here. Huh? That posting is about dividing quadrature, not Pluto. Actually, I think I linked to the posting that came immediately before the one I really wanted. Look at http://emergent.unpy.net/projects/01149348342 There is a schematic, board layout, and source code for a very tiny quadrature divider. Unfortunately, it doesn't help with index. Many high-end encoders gate the index pulse so it's only on for one quadrature phase. The tiny software would need to be changed to extend the index pulse for a full output count cycle (it's not obvious to me how to do that with the table-driven approach, after 2 minutes of looking at it) -Steve -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Tue, Aug 18, 2009 at 10:19:17AM -0400, Stephen Wille Padnos wrote: Unfortunately, it doesn't help with index. For threading/tapping, it doesn't matter if you sometimes miss the index. Chris -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Tue, 18 Aug 2009 10:19:17 -0400, you wrote: Unfortunately, it doesn't help with index. Many high-end encoders gate the index pulse so it's only on for one quadrature phase. The tiny software would need to be changed to extend the index pulse for a full output count cycle (it's not obvious to me how to do that with the table-driven approach, after 2 minutes of looking at it) Your right Steve, the index is only one quadrature phase. At anything above 200 rpm with the 1024 pulse encoder it's pot luck whether EMC sees it. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Mon, 17 Aug 2009 16:54:54 -0700 (PDT), you wrote: If I get a free bit of time I'll cobble together a quadrature divider, basically: 1. Input digital filter 2. Quadrature decoder (quadrature to up/down) 3. Up down modulo N counter (for divide by N) 4. 2 bit up/down counter 5. 2 bit binary -- quadrature encoder 6. Optional index stretcher I even think we have some CPLD bds we never used that I can send over for shipping cost. That's very kind of you Peter, I'd appreciate that very much. From experiments looks like the index stretcher is a must ;) I'm not happy with the Chinese 1024 pulse encoder, but I've also got an unused Stegmann DG60L 500 pulse per rev encoder I'm going to test. Looking at the docs that too only outputs a single quadrature count index pulse, but it's much better quality and I'm hoping the signals out from it are cleaner. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Tue, 18 Aug 2009, Steve Blackmore wrote: Date: Tue, 18 Aug 2009 22:16:48 +0100 From: Steve Blackmore st...@pilotltd.net To: Peter C. Wallace p...@mesanet.com, EMC2-Users-List emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Realistic spindle encoder count for parallel port? On Mon, 17 Aug 2009 16:54:54 -0700 (PDT), you wrote: If I get a free bit of time I'll cobble together a quadrature divider, basically: 1. Input digital filter 2. Quadrature decoder (quadrature to up/down) 3. Up down modulo N counter (for divide by N) 4. 2 bit up/down counter 5. 2 bit binary -- quadrature encoder 6. Optional index stretcher I even think we have some CPLD bds we never used that I can send over for shipping cost. That's very kind of you Peter, I'd appreciate that very much. From experiments looks like the index stretcher is a must ;) I'm not happy with the Chinese 1024 pulse encoder, but I've also got an unused Stegmann DG60L 500 pulse per rev encoder I'm going to test. Looking at the docs that too only outputs a single quadrature count index pulse, but it's much better quality and I'm hoping the signals out from it are cleaner. Steve Blackmore -- I'll have some time at the end of the week and Ill put something together. I'll also try and make the long index synchronous with the divided Quadrature this will require the total encoder counts to be evenly divisable by the divide ratio. If I fail at that I'll just use a digital one-shot Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Tuesday 18 August 2009, Peter C. Wallace wrote: On Tue, 18 Aug 2009, Steve Blackmore wrote: Date: Tue, 18 Aug 2009 22:16:48 +0100 From: Steve Blackmore st...@pilotltd.net To: Peter C. Wallace p...@mesanet.com, EMC2-Users-List emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Realistic spindle encoder count for parallel port? On Mon, 17 Aug 2009 16:54:54 -0700 (PDT), you wrote: If I get a free bit of time I'll cobble together a quadrature divider, basically: 1. Input digital filter 2. Quadrature decoder (quadrature to up/down) 3. Up down modulo N counter (for divide by N) 4. 2 bit up/down counter 5. 2 bit binary -- quadrature encoder 6. Optional index stretcher I even think we have some CPLD bds we never used that I can send over for shipping cost. That's very kind of you Peter, I'd appreciate that very much. From experiments looks like the index stretcher is a must ;) I'm not happy with the Chinese 1024 pulse encoder, but I've also got an unused Stegmann DG60L 500 pulse per rev encoder I'm going to test. Looking at the docs that too only outputs a single quadrature count index pulse, but it's much better quality and I'm hoping the signals out from it are cleaner. Steve Blackmore -- I'll have some time at the end of the week and Ill put something together. I'll also try and make the long index synchronous with the divided Quadrature this will require the total encoder counts to be evenly divisable by the divide ratio. If I fail at that I'll just use a digital one-shot I can see potential problems with that too. Related to direction of rotation. Suggestion: latch it on its rising edge, which if the encoder is properly timed should give one whole output count time to read it, then let the trailing edge of the ports read strobe reset it so you only get it once even at creep speeds. Is that practical? Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. --- --- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. https://www.nrahq.org/nrabonus/accept-membership.asp Just when you thought you were winning the rat race, along comes a faster rat!! -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Sun, 16 Aug 2009 21:00:31 -0400, you wrote: Sounds like it is time to go back to your homemade 90 count encoder. If you just intend threading and not a rotary axis with positioning, then it should work well. Hi Steve - Not an option I'm afraid, with the 3 speed belt drive installed the timing disc hits the belt tensioner arm and there's no space to fit it any other way. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
If this is just for threading then you could run in counter mode. That would effectively divide the pulse rate by 4. If you still have problems then a simple binary counter such as a 74HCT93 can be used to divide one channel (counter mode only uses one channel) by 2,4,8 or whatever. 74HC series logic chips only cost a few pence. If you want I can send you a circuit diagram of how to connect up a 74HCT93. It is dead simple and can even be made by simply soldering a few wires directly to the chip. Les Steve Blackmore wrote: On Sun, 16 Aug 2009 21:00:31 -0400, you wrote: Sounds like it is time to go back to your homemade 90 count encoder. If you just intend threading and not a rotary axis with positioning, then it should work well. Hi Steve - Not an option I'm afraid, with the 3 speed belt drive installed the timing disc hits the belt tensioner arm and there's no space to fit it any other way. Steve Blackmore -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Sun, 16 Aug 2009 21:03:54 -0700 (PDT), you wrote: Can you use both encoders at once? High resolution for low speed and Low resolution for high speed? You could also do this with the high resolution encoder and a gizmo like the USdigital divider, only with 2 selectable divide ratios run from a single I/O bit, say 1/1 and 1/64. This is easily do-able in a $ 1.20 CPLD A divider would work well, but I'm no programmer and wouldn't know where to start. If I can't find a simple solution it looks like I'll have to get another encoder. Would you need the index at high speeds? My normal working range is 600-1200 rpm. Most of my threading is done at 600-1000 rpm, depending on pitch. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Mon, 17 Aug 2009 23:10:12 +0100, you wrote: If this is just for threading then you could run in counter mode. That would effectively divide the pulse rate by 4. If you still have problems then a simple binary counter such as a 74HCT93 can be used to divide one channel (counter mode only uses one channel) by 2,4,8 or whatever. 74HC series logic chips only cost a few pence. Yep - only for threading, but in counter mode can EMC still make corrections for spindle speed variations? If you want I can send you a circuit diagram of how to connect up a 74HCT93. It is dead simple and can even be made by simply soldering a few wires directly to the chip. Yes please Les, if nothing else it will get me a temporary solution. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Realistic spindle encoder count for parallel port?
Hi Guys, what's a realistic number of PPR for a lathe spindle encoder via a parallel port in EMC. Spindle is capable of 3500 rpm. My home made encoder had 90, but I've altered the drive system and fitted a 1024 PPR encoder with index. Output is via differential line drivers. I've changed the scale factor but it starts loosing pulses at 600 rpm or so?? Here's what's in my ini file [EMCMOT] EMCMOT = motmod COMM_TIMEOUT = 1.0 COMM_WAIT = 0.010 BASE_PERIOD = 62500 SERVO_PERIOD = 100 Hal file reads setp encoder.0.position-scale 360.00 net spindle-position encoder.0.position = motion.spindle-revs net spindle-velocity encoder.0.velocity = motion.spindle-speed-in net spindle-index-enable encoder.0.index-enable = motion.spindle-index-enable net spindle-phase-a encoder.0.phase-A net spindle-phase-b encoder.0.phase-B net spindle-index encoder.0.phase-Z Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Hi, First, I assume the 1024 PPR indicates that the resolution of the encoder is 1024 cycles per revolution as defined in http://www.motion-control-info.com/encoder_glossary.html Hence 1024 full AB cycles per revolution. When using a 1024 PPR encoder, there will be 1024 A and 1024 B pulses per revolution. Since the A/B signals are directly read by the PC (via the parallel port), we have to make sure that every of the 4 phases of each pulse is sampled at least once by the PC in the time of one pulse. When pulses change faster than the PC samples, the PC will not see the changes, or loose track of the phase relation between the signals, and miss pulses. To compensate for possible fluctuations and inaccuracy of the phase and symmetry of the A/B pulses, we have to sample more often, e.g. 8 times per pulse-cycle (my guess). When running at 3500 rpm, there are (3500/60) * 1024 = 59733 pulses per second. When we want to sample 8 times per such pulse, we have to sample at least at 59733 * 8 = 477867 or about 480 000 times per second. That is once every 2.1 microseconds. Since your BASE_PERIOD = 62500 nanoseconds (62.5 microseconds) the sampling is about 30 times too low to be safe. When you keep the BASE_PERIOD = 62500 unchanged, and if you want to sample 8 times per pulse, the maximum number of pulses per revolution is: 1 / ((3500/60) * 8 * BASE_PERIOD) = 1 / ((3500/60) * 8 * (BASE_PERIOD / 10)) = 34 Hence, i think that your encoder should have no more than 34 PPR when keeping the rest unchanged and when using the safety factor of 8 pulse-reads per pulse (which still gives not too much safety). So, i am surprised that you can go up to about 600rpm without loosing pulses. Can anyone check this, please? Luc Steve Blackmore wrote: Hi Guys, what's a realistic number of PPR for a lathe spindle encoder via a parallel port in EMC. Spindle is capable of 3500 rpm. My home made encoder had 90, but I've altered the drive system and fitted a 1024 PPR encoder with index. Output is via differential line drivers. I've changed the scale factor but it starts loosing pulses at 600 rpm or so?? Here's what's in my ini file [EMCMOT] EMCMOT = motmod COMM_TIMEOUT = 1.0 COMM_WAIT = 0.010 BASE_PERIOD = 62500 SERVO_PERIOD = 100 Hal file reads setp encoder.0.position-scale 360.00 net spindle-position encoder.0.position = motion.spindle-revs net spindle-velocity encoder.0.velocity = motion.spindle-speed-in net spindle-index-enable encoder.0.index-enable = motion.spindle-index-enable net spindle-phase-a encoder.0.phase-A net spindle-phase-b encoder.0.phase-B net spindle-index encoder.0.phase-Z Steve Blackmore -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: Hi Guys, what's a realistic number of PPR for a lathe spindle encoder via a parallel port in EMC. Spindle is capable of 3500 rpm. It's dependent on your BASE_PERIOD. You can theoretically count one quadrature phase per period, but it's better to have two periods per count - gives better noise margin (noise in this case being encoder phase issues and latency variations). My home made encoder had 90, but I've altered the drive system and fitted a 1024 PPR encoder with index. Output is via differential line drivers. I've changed the scale factor but it starts loosing pulses at 600 rpm or so?? Hmmm - you must have a 256 cycle encoder, which gives you 1024 counts per rev. At 10 RPS, that's 10240 counts per second, which is a reasonable number for a 16 kHz base thread. At 3500 RPM you need close to 6 counts per second. I'd guess that your PCs latency is 17k or so (calculated as (1/10240-62500ns)/2). You should check the latency, and see how fast you can run the base thread. You can only count reliably if the counts come in slower than BASE_PERIOD+2*latency. If the latency is actually 17k, you probably can't run the base period faster than 35000-4 ns, which will only increase the top speed to about 1000 RPM, give or take. I don't know of any computer that can do 60k counts/sec reliably on the parport. The best thing to do is probably to get a Mesa card, either PCI or parallel port connected. You'll get smoother step generation too. Hal file reads setp encoder.0.position-scale 360.00 This should now be 4096, unless you have a 256 cycle encoder which is 1024 phases per rev (in which case it should be 1024). - Steve -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
You might have a look at http://www.usdigital.com/products/interfaces/encoder/converters/edivide/ Something like this would allow you to experiment with speed vs resolution and still keep the encoder you've got on there. On Sun, 2009-08-16 at 10:51 +0100, Steve Blackmore wrote: Hi Guys, what's a realistic number of PPR for a lathe spindle encoder via a parallel port in EMC. Spindle is capable of 3500 rpm. My home made encoder had 90, but I've altered the drive system and fitted a 1024 PPR encoder with index. Output is via differential line drivers. I've changed the scale factor but it starts loosing pulses at 600 rpm or so?? -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: Hi Guys, what's a realistic number of PPR for a lathe spindle encoder via a parallel port in EMC. Spindle is capable of 3500 rpm. My home made encoder had 90, but I've altered the drive system and fitted a 1024 PPR encoder with index. Output is via differential line drivers. I've changed the scale factor but it starts loosing pulses at 600 rpm or so?? Here's what's in my ini file [EMCMOT] EMCMOT = motmod COMM_TIMEOUT = 1.0 COMM_WAIT = 0.010 BASE_PERIOD = 62500 SERVO_PERIOD = 100 OK, base period is 62.5 us. For safety, we should never have encoder counts coming faster than twice that period. So, that is 125 us or 8000 Hz. Just to pick round numbers, 3600 RPM is 60 rev/second, or 16.67 ms. So, we can read no more than 8000 counts/second, and need to fit that into .01667 seconds. 8000 * .016667 = 133. So, you need a 128 or 100 count/rev encoder. Encoders are usually specified as cycles/rev (also written pulses/rev) and that is 4 x less than the count rate. So, you need a 25 or 32 cycle/rev encoder! That's why people use hardware assist to handle these encoder counting chores. Jon -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Sun, 16 Aug 2009 10:58:55 -0400, you wrote: Hal file reads setp encoder.0.position-scale 360.00 This should now be 4096, unless you have a 256 cycle encoder which is 1024 phases per rev (in which case it should be 1024). Sorry - It does read 4096, I cut and pasted a copy I've got on this PC and forgot to edit. Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Sun, 16 Aug 2009 12:10:50 -0500, you wrote: OK, base period is 62.5 us. For safety, we should never have encoder counts coming faster than twice that period. So, that is 125 us or 8000 Hz. Just to pick round numbers, 3600 RPM is 60 rev/second, or 16.67 ms. So, we can read no more than 8000 counts/second, and need to fit that into .01667 seconds. 8000 * .016667 = 133. So, you need a 128 or 100 count/rev encoder. Encoders are usually specified as cycles/rev (also written pulses/rev) and that is 4 x less than the count rate. So, you need a 25 or 32 cycle/rev encoder! That's why people use hardware assist to handle these encoder counting chores. Looks like a Mesa card may be a good bet, but... $199 + 22.5% import duty + carriage + 15% VAT = a lot :( I wonder how well I can get away with 1 pulse per rev? Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Steve Blackmore wrote: On Sun, 16 Aug 2009 12:10:50 -0500, you wrote: OK, base period is 62.5 us. For safety, we should never have encoder counts coming faster than twice that period. So, that is 125 us or 8000 Hz. Just to pick round numbers, 3600 RPM is 60 rev/second, or 16.67 ms. So, we can read no more than 8000 counts/second, and need to fit that into .01667 seconds. 8000 * .016667 = 133. So, you need a 128 or 100 count/rev encoder. Encoders are usually specified as cycles/rev (also written pulses/rev) and that is 4 x less than the count rate. So, you need a 25 or 32 cycle/rev encoder! That's why people use hardware assist to handle these encoder counting chores. Looks like a Mesa card may be a good bet, but... $199 + 22.5% import duty + carriage + 15% VAT = a lot :( You could get the 7i43 instead, which is $89. It connects to the parallel port, which may limit your servo loop rate eventually, but otherwise it's the same thing as a 5i20. Oh, that and the fact it only has two I/O connectors instead of 3. - Steve -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Sun, 16 Aug 2009 10:48:44 -0500, you wrote: You might have a look at http://www.usdigital.com/products/interfaces/encoder/converters/edivide/ Something like this would allow you to experiment with speed vs resolution and still keep the encoder you've got on there. Thanks - Would be good Ray, but the price is prohibitive over here. $50.95 + 22.5% import duty + $46.98 postage + VAT = $126 (approx) !! Postage is a killer!! Do you know of any IC's or circuits that can do the same? Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
Sounds like it is time to go back to your homemade 90 count encoder. If you just intend threading and not a rotary axis with positioning, then it should work well. Steve Stallings -Original Message- From: Steve Blackmore [mailto:st...@pilotltd.net] Sent: Sunday, August 16, 2009 8:42 PM To: EMC2-Users-List Subject: Re: [Emc-users] Realistic spindle encoder count for parallel port? On Sun, 16 Aug 2009 12:10:50 -0500, you wrote: OK, base period is 62.5 us. For safety, we should never have encoder counts coming faster than twice that period. So, that is 125 us or 8000 Hz. Just to pick round numbers, 3600 RPM is 60 rev/second, or 16.67 ms. So, we can read no more than 8000 counts/second, and need to fit that into .01667 seconds. 8000 * .016667 = 133. So, you need a 128 or 100 count/rev encoder. Encoders are usually specified as cycles/rev (also written pulses/rev) and that is 4 x less than the count rate. So, you need a 25 or 32 cycle/rev encoder! That's why people use hardware assist to handle these encoder counting chores. Looks like a Mesa card may be a good bet, but... $199 + 22.5% import duty + carriage + 15% VAT = a lot :( I wonder how well I can get away with 1 pulse per rev? Steve Blackmore -- -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
I just got one of these encoders and installed on a servo motor: http://www.cui.com/adtemplate.asp?invky=490429 http://amtencoder.com/ The encoder has programmable (48-20-48 ppr) resolution and comes with a kit that allows mounting on several shaft sizes. Available from digi-key, they list a Europe phone no. too. no afiliation etc -- but so far it seems to be working fine. -- Dewey Garrett -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Mon, 17 Aug 2009, Steve Blackmore wrote: Date: Mon, 17 Aug 2009 01:42:02 +0100 From: Steve Blackmore st...@pilotltd.net To: EMC2-Users-List emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Realistic spindle encoder count for parallel port? On Sun, 16 Aug 2009 12:10:50 -0500, you wrote: OK, base period is 62.5 us. For safety, we should never have encoder counts coming faster than twice that period. So, that is 125 us or 8000 Hz. Just to pick round numbers, 3600 RPM is 60 rev/second, or 16.67 ms. So, we can read no more than 8000 counts/second, and need to fit that into .01667 seconds. 8000 * .016667 = 133. So, you need a 128 or 100 count/rev encoder. Encoders are usually specified as cycles/rev (also written pulses/rev) and that is 4 x less than the count rate. So, you need a 25 or 32 cycle/rev encoder! That's why people use hardware assist to handle these encoder counting chores. Looks like a Mesa card may be a good bet, but... $199 + 22.5% import duty + carriage + 15% VAT = a lot :( I wonder how well I can get away with 1 pulse per rev? Steve Blackmore -- Can you use both encoders at once? High resolution for low speed and Low resolution for high speed? You could also do this with the high resolution encoder and a gizmo like the USdigital divider, only with 2 selectable divide ratios run from a single I/O bit, say 1/1 and 1/64. This is easily do-able in a $ 1.20 CPLD Would you need the index at high speeds? Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Realistic spindle encoder count for parallel port?
On Mon, 17 Aug 2009, Steve Blackmore wrote: Date: Mon, 17 Aug 2009 01:42:02 +0100 From: Steve Blackmore st...@pilotltd.net To: EMC2-Users-List emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Realistic spindle encoder count for parallel port? On Sun, 16 Aug 2009 12:10:50 -0500, you wrote: OK, base period is 62.5 us. For safety, we should never have encoder counts coming faster than twice that period. So, that is 125 us or 8000 Hz. Just to pick round numbers, 3600 RPM is 60 rev/second, or 16.67 ms. So, we can read no more than 8000 counts/second, and need to fit that into .01667 seconds. 8000 * .016667 = 133. So, you need a 128 or 100 count/rev encoder. Encoders are usually specified as cycles/rev (also written pulses/rev) and that is 4 x less than the count rate. So, you need a 25 or 32 cycle/rev encoder! That's why people use hardware assist to handle these encoder counting chores. Looks like a Mesa card may be a good bet, but... $199 + 22.5% import duty + carriage + 15% VAT = a lot :( I wonder how well I can get away with 1 pulse per rev? Steve Blackmore -- Can you use both encoders at once? High resolution for low speed and Low resolution for high speed? You could also do this with the high resolution encoder and a gizmo like the USdigital divider, only with 2 selectable divide ratios run from a single I/O bit, say 1/1 and 1/64. This is easily do-able in a $ 1.20 CPLD Would you need the index at high speeds? Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
