I've read several of the other replies. They all seem to have good advice, but what I would tend to look at first is the grounding of your signals. It could be that your direction signal could be misinterpreted by the driver board because your reference point (ground) isn't as quiet as it needs to be to get a 100% consistent signal.
Sometimes the solution is just a larger ground wire, sometimes some signals need to be isolated from ground to receive the signal consistently. Do you have access to an oscilloscope? If so, ground the scope to your computer and read the ground line on your driver board. If the voltage at the driver should be only tenths of a volt. If it is greater than that, some changing is in order. I also divide and conquer when I can - halscope is a good window into the EMC actions, and the scope is the tool for outside the computer. > From: jpe...@peasej.com > To: emc-users@lists.sourceforge.net > Date: Sun, 5 Jul 2009 12:25:16 -0700 > Subject: [Emc-users] Weird EMC2 tuning issue (direction reverses > intermittently) > > I am working on tuning my homebuilt HobbyCNC machine with EMC 2.3. I > am using the HobbyCNC EZ driver board to interface with my PC. I have > things working, but am working on tweaking the ini settings to get as > high of feedrate as I can reliably. > > One mysterious issue I've seen that I'm trying to figure out is that > very, very rarely, a movement command to the milling machine will make > an axis move the correct distance in the INCORRECT direction. This can > happen either when running a gcode program or manually jogging the > axis in a direction. If it occurs during a jog, usually all I have to > do to fix it is stop jogging and then start again. > > The computer interfaces with the driver board using the normal STEP, > DIRECTION signals for each axis over the parallel port. > > The question is, where do you think this issue is being introduced? It > seems unlikely that EMC2 could be getting the direction wrong in > isolated cases, but, to me, it seems equally unlikely that the driver > board is driving a particular direction incorrectly in isolated cases. > This might also be a symptom of operating at too high of a feedrate > (in the current case I have been trying to make 40 inches per second > work), but I'm hoping to hear from someone who has seen and fixed this > issue before I try dropping the feedrate. Like I say, this issue crops > maybe .05% of the time - very rare, but enough to affect the overall > reliability of my machine. > > Any ideas? > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _________________________________________________________________ Lauren found her dream laptop. Find the PC that’s right for you. http://www.microsoft.com/windows/choosepc/?ocid=ftp_val_wl_290 ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
