On Fri, 2009-02-13 at 23:50 -0600, cogo...@verizon.net wrote: > where I work we have a Shizuoka with an old Bandit control. The three > servo drives still appear to work. It has tachometer feedback to the > servo drives, and resolver feedback to the computer portion, which is > in a coma.
I have a stepper version of an ST-N: http://www.wallacecompany.com/machine_shop/Shizuoka/ > I would like to convert this to an EMC2 servo system with quadrature > encoders for feedback to EMC2, and for the proof of concept, I'd like > to have EMC2 do pulse-width-modulation of 3 parallel port pins, which > I would convert to +- 10V with a quad op amp and filter circuit > (already have those parts). This can be done for a spindle motor control, but I think the filter's reaction time will make tuning very difficult. Someone here may correct me on this. > Since I'd be spending someone else's money, I'd like to avoid buying a > Pluto servo board, or a MESA 5i20 until I can prove it can cut parts. I have little doubt that if your Shizuoka is in decent condition mechanically, EMC will make it a better machine than the Bandit controller did on it's best day. I don't think a machine of this size lends itself well to hobby based jury systems,so I think you'll spend more time trying to get your jury circuits to work, than to just study and copy formal setups from EMC machines that have already been successfully converted. > I'm also planning on doing an "open quadrature encoder" project, to > save some bucks up front, and hopefully come up with a cheap and > fairly reliable replacement for expensive encoders. I also have given this some thought. I am finding that encoders are fairly simple in theory, but making one that works well is a big job. I think the most cost effective encoders are the ones I built using US Digital disks and sensors: http://www.wallacecompany.com/cnc_lathe/HNC/00001-1a.jpg http://www.wallacecompany.com/cnc_lathe/HNC/00011-1a.jpg > The Question: Where can I find info that would help me set up the > HAL to input from a quadrature encoder on two parallel port pins (the > easy part), and output a pulse width modulated stream on another pin > of the parallel port (the hard part), while using this to control the > position of a servo motor? HAL allows you to connect signals and pins whichever way you decide. There are sample HAL files that you can use as a reference. From Jeff's etch-servo example: http://emergent.unpy.net/projects/01142347802 the X encoder is connected like this: ... net enc0A encoder.0.phase-A <= parport.0.pin-10-in net enc0B encoder.0.phase-B <= parport.0.pin-11-in ... This connects the first parallel port input pins 10 and 11 to the motion control software encoder pins. You can change these lines to connect the pins of your choice. You should read through the Integrator's Manual a few times, and study the sample .ini and .hal files, before expecting to understand how EMC and HAL works. It took me a long time to get the hang of it, you just need to be patient and ask questions when you get stuck. > I suspect that if I had a fast PC, with a fast thread running about > 25uSEC, even if I were satisfied with low bit resolution in the PWM, > the filter would slow down the +-10V output to the point where the > machine would probably be stepper slow, or even slower; but if it > could (slowly) cut parts out reliably, and with precision, it would be > easy to justify getting a servo card for the machine. This machine > would be backup for our Fadal 4020 Again, I don't see any real magic to getting EMC to work well on your machine. If you want to reuse your resolvers, there may be some issues to work out, but Jon (Pico Systems) has a converter available and can help with the setup. If you have a tool changer, I am in the process of getting mine to work, so I can help you with that part. > > The 5V power supply for the controller had died, and I bought some > transistors and repaired it, but it still won't cut parts. That's why > the caution about investing in it. Good luck -------------- Kirk http://www.wallacecompany.com/machine_shop/ ------------------------------------------------------------------------------ Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
