The C10S looks as if it provides 3.3V (parallel port) to 5V (driving the stepper drivers) voltage translation, but I'd assume any optoisolator interface would do that, including the homebrew version you were using?
There seems to be an IM483-NR version of your stepper driver that's listed as "noise reduction at inputs". So the IM483 doesn't have any sort of noise filtering at its inputs? http://motion.schneider-electric.com/products/im483.html I'd focus on killing the noise. 1.8V of noise is a killer on a 5V signal. I'd run shielded cable for everything - motors, limit switches... everything. Ground the shields directly to the subpanel where the stepper drivers and optoisolator card are mounted. Leave the other ends of the cable shielding unconnected to prevent current loops (current flow in the shield). Don't run the power cabling next to control signal cabling. Use a good quality IEEE 1284 bidirectional parallel port cable. Are you sure the optoisolator board and/or stepper drivers are wired correctly? The inputs on the cheap eBay stepper drivers that I use are optoisolated. To turn on the optoisolator at the inputs would require a few milliamps of current, which is a lot for electromagnetic interference noise to source. If you have stepper driver inputs that have a floating common that is internally biasing itself based on leakage currents from the inputs, then the inputs would be much more likely to trigger on noise. On 03/08/2015 03:34 PM, Neil wrote: > Hi all, > > Haven't found a clear answer to this yet in the archives, so hoping > someone can help. > > I've just gotten back to a homebrew CNC machine project from a few years > ago and need to figure out why I'm getting incorrect/missing steps. > Using an Intel D525MW and IM483 stepper drivers. I was using a homebrew > opto-isolator board, and got the incorrect/lost steps, so I tried > without (direct from par-port to drives) and getting a lot of chatter. > With this, moving the X-axis gets me enough noise on the Y-axis lines > that the Y-axis will move. > > An oscilloscope shows me that the parallel-port output seems to be 3.3V, > and I've got noise of up to 1.8V on the step line! Other than shielded > wires, I need a decent buffered breakout board. Space is very tight, so > leaning towards the C10S from cnc4pc.com here... > http://www.cnc4pc.com/Store/osc/product_info.php?cPath=33&products_id=696 > > Do you think this would resolve my issue? > > Thanks. > > > ------------------------------------------------------------------------------ > Dive into the World of Parallel Programming The Go Parallel Website, sponsored > by Intel and developed in partnership with Slashdot Media, is your hub for all > things parallel software development, from weekly thought leadership blogs to > news, videos, case studies, tutorials and more. Take a look and join the > conversation now. http://goparallel.sourceforge.net/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
