Brian J. Carpenter wrote: > Hello, > > I have a small machine which I have had setup and running with other > software for a year now. I recently tried EMC and am having some > issues. From what I have read, support for Homing is somewhat recent. I > am running the latest version, or atleast there are no updates showing. > (I installed from the LiveCD) > > When I try to home the machine, it runs at full speed and bashes into > the hard stop, ignoring the home switch. The switch does work, and I > have tried inverting the signal in stepconf, but no luck. > > The machine homes fine when using another software package, but I really > prefer the flexible concept of EMC. > > My axis is setup as follows: > > [AXIS_0] > TYPE = LINEAR > HOME = 0.0 > MAX_VELOCITY = 0.3 > MAX_ACCELERATION = 0.5 > STEPGEN_MAXACCEL = 0.525 > SCALE = 10000.0 > FERROR = 0.05 > MIN_FERROR = 0.01 > MIN_LIMIT = -4.375 > MAX_LIMIT = 4.375 > HOME_OFFSET = -4.375000 > SEARCH_VEL = 0.020000 > LATCH_VEL = 0.100000 > HOME_SEQUENCE = 1 > > It seems that no matter what i set the SEARCH_VEL to, it runs at full > speed (18 in/m)! Is there a simple fix for this? Can anyone tell me > what EMC expects the switch state to be, true when at home, or > reversed? Or does it need Normally Open switches? > > Thanks in advance for any help. > > -- Brian Carpenter
Are you absolutely sure it runs at full speed as soon as you hit home? After it finds the home switch, it will consider the switch location to be -4.375, and it will move at full speed to 0.000. Perhaps something is making it think it found home as soon as you start the homing process? Otherwise, I can't imagine how it would run at full speed. That code is straightforward and well tested by many users. I need some background: Steppers or servos? Do normal jog moves work correctly, proper speed and proper direction, on all axes? HOME_SEQUENCE should start at zero for the axis you want to home first, and primarily affects HomeAll. I'd comment out the HOME_SEQUENCE line until each axis homes properly by itself. Does this problem happen on all axes, or only AXIS_0? The motion controller pins axis.N.home-sw-in (or something like that, I don't have the docs handy at the moment) should be true when you are on the switch, and false when you are not. You can (and should) test that using halmeter and manually actuating the switch before you apply power to the motors. I just noticed one problem, although it doesn't explain your symptoms. You have HOME_OFFSET = -4.375. That means the home switch is at the negative end of your axis. But SEARCH_VEL is positive - that means the search will go in the wrong direction. I think I just realized the problem - is the listing of variables above an exact copy/paste of your ini file section? If so, the homing variable names are wrong. SEARCH_VEL, LATCH_VEL, and others are supposed to start with HOME_, as in this section of one of the sample configs: # First axis [AXIS_0] TYPE = LINEAR HOME = 0.000 MAX_VELOCITY = 5.0 MAX_ACCELERATION = 20.0 INPUT_SCALE = 33865 MAX_OUTPUT = 10.0 MIN_LIMIT = -14.0 MAX_LIMIT = 14.0 FERROR = 0.050 MIN_FERROR = 0.010 HOME_OFFSET = 14.3 HOME_SEARCH_VEL = 2.5 HOME_LATCH_VEL = -0.25 HOME_USE_INDEX = YES HOME_IGNORE_LIMITS = NO HOME_SEQUENCE = 1 If HOME_SEARCH_VEL isn't in the ini file, EMC assumes that it is zero. A zero search vel means you don't have switches, and simply want to set the current position as home. Using that with a non-zero HOME_OFFSET means that as soon as you hit Home, the machine sets the current position to HOME_OFFSET (-4.375 on your machine), and then rapids to HOME (0.000 on your machine). Hope this helps, John Kasunich ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
