H & J Johnson wrote: >Steven, thanks for taking the time to reply. I'm by no means a programer >nor do I expect that I'd get proficient at it in the time frame needed [or to >the level that would be required]. I'm more interested in being able to >'look up' stuff and learn to read code a little.. to understand what >is be asked where etc. > > Actually, I think I might have been wrong about where to start. Get yourself an old throwaway PC, and install Linux using the EMC2 liveCD from linuxcnc.org. You will find that it's very similar to what you're used to, just some of the details are different. (The "program menu" is at the top left of the screen, and is labeled "Applications" instead of being at the bottom left and labelled "start" ...)
Play around, and don't expect to save anything from this install. You can always intsall again if you do something that you can't fix. (Note: you can do a lot of experimentation just by booting from the CD - it's a fully functional system - but you may be nervous about destroying data, that's why I suggest doing an install on a PC that has no useful data on it) >On the motion controler I should have called it a step generator. I've >used the G100 and have [haven't installed it yet] a Smooth Stepper >for Mach3. > OK, I wasn't sure. There are several similar units for EMC2, but none use ethernet or USB for communications - they're either PCI or parallel port connected. >I've been satisfied w/ how Mach3 has run the only >thing that is driving my switch to EMC is the ability to do proper tool >offsets while in 5 axis. Brian [from Artsoft] has advised me that he >doesn't currently have plans to add this functionality. He's a busy guy >and my move is in no way a slight against him. > > None taken :) >I'm sure that a switch to EMC is more daunting in the initial stages >than it is once one jumps in. However I'm at a bit of a loss since I've >no experiance w/ Linux or EMC. > > It's more in your head than anywhere else :) The differences between Linux and Windows today are a bit like the differences between cars. Some have the headlight switch on the dash, others on a stick on the steering column. Some need you to press a button to switch high/low beam, others need to be pulled to toggle, others are push-pull ... They all do more or less the same thing, but the controls are slightly different. You probably don't have much trepidation about jumping into an unfamiliar rental car - try adopting the same attitude toward a new operating system. (note: I'm not saying that there are no differences, or that it will never be frustrating to figure out how to do something on Linux that you already know how to do on Windows, it's just that most of the differences in day to day use are small details) >I've down loaded the manuals and will start reading them this weekend. > >Has there been configurations created for a 5 axis system where a person >can just add the head dimensions to allow the software to compute the tool >offsets? > Yes, maybe. It depends on the construction of the head. There are two versions that I know of, one of which is included with EMC2 (5axiskins). Stuart Stevenson has also made a kinematics file for one of his Cincinatti 5-axis machines, which takes many things into account, including certain build errors. I don't know if that's finished yet. > I'm hoping I can put a auto tool length system in as well so the >machine automatically measures the tool length on each ATC. > > Fully automatic measurement needs some G-code support at the moment (you can call a subroutine to measure and apply the length) >Just had a look at the Motec stuff, I see the 100 series has 8 axis which >would suffice [I need min of 6, prefer 7] for my setup. I'm not seeing >anywhere, where it states that it will output step/dir, as I re-read your >reply I believe that is infact the case. > > No, the Motenc hardware outptus analog control voltages. >Are the Mesa cards 'stackable' in that I can add as many as I need [IIRC >they have 4 axis cards so I'd need two?] Does Mesa provide some form >of a configuration file w/ their cards to help a user get to [almost] plug >and play, or does one have to manually configure the card etc? > > You can mix and match anything you want. You can use parallel-port software PWM to control spindle speed, while using a Mesa card for some motors and a Pico Systems card (connected via a separate parallel port) for some other motors. They can be any mix of velocity control, torque control, PWM, and step/dir motors. A single Mesa 5i22 card can handle as many as 16 servos, though I'm not sure there's an FPGA configuration for that. The cards are reprogrammable, and you can select different "firmware" for the cards as you see fit, even using different firmware for each card when you have more than one. The Mesa cards have from 2 to 4 "IO Connectors". Each connector can support up to 4 motors, or 24 I/O lines, and in some cases you can use motor controls and I/O on the same connector. >Also on alot of this hardware I'm seeing the closed loop of the encoders >coming back in. How does this play w/ a closed loop drive where it requires >the encoder connection back to it's self, to be able to accuratly drive the >motors? [ie; my Granite drives] > > You can run the encoder back to EMC as well as to the drive. It shouldn't be too much of a load on the encoder line drivers. For the Fanuc Yellow Caps, you may want to look into an analog velocity mode servo amp. I don't know how well the Granite drives are matched to those relatively large motors. I wouldn't choose step/dir controlled drives unless I had to (for example, because that's all my software supports ... :) ), I'd much prefer to close the loop in the PC. I think you get snoother motion (which can translate to better surface finish), and you also have more advanced alogrithms available. The PID software in EMC2 is actually PIDFF - it has feed-forward terms that can be used to get better performance under acceleration. >Thanks VERY much for your help and advice.. > > Sure. I just hope I'm right :) - 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
