Hello John, I connected it using the differential pairs. Although the encoder says is TTL differential and doesn't mention anything about RS-422 but it seems to be working fine.
From what I've reading I'm not sure if halscope can sense that index pulse because of the same reason I suspect hal is missing it. I'm triggering the index with a custom made component to apply offsets to the X axis. I even forced the component to set index to 1 on each iteration without even sensing if it's on 0 and the same thing happens, if I turn it too fast the index pulse is skipped. Unfortunately this is the only encoder I have here to make the tests, so I will not have a real conclusion until I test the differential encoder on the Mazak. El sáb., 21 mar. 2020 a las 1:15, John Dammeyer (<jo...@autoartisans.com>) escribió: > > > > -----Original Message----- > > From: Leonardo Marsaglia [mailto:ldmarsag...@gmail.com] > > Sent: March-20-20 8:49 PM > > To: Enhanced Machine Controller (EMC) > > Subject: [Emc-users] Question about index pulse on high resolution > encoder > > > > Hello guys, > > > > I'm testing a phisical encoder to simulate how the spindle will work with > > the external offsets. So far so good but I need to clarify something > that I > > suspect. Here it comes: > > > > The encoder I'm testing is an ERN471 from Heidenhain. A beast of encoder. > > It says 5.000 line counts on the datasheet but also says it outputs > 125.000 > > signal periods per revolution, so when I read it in LinuxCNC with a scale > > of 1 I find that I'm having 500.000 pulses per turn. A lot of resolution. > > I'm scaling it to 1024 since this is what I have on the Mazak. > > > > My concern is (and I think this is to be expected) that I have missing > > index pulses if I rotate the encoder too fast with my fingers. I tried to > > use a shorter servo-period and that seemed to improve things a little but > > not solving the problem always. > > > > Is this what's happening? Should I not expect this behaviour with the > 1024 > > PPR encoder and the spindle turning at about 200 RPM ? > > > > I would like to hear your thoughts just to be relaxed, since a missing > > index pulse on this kind of processes is likely to break the tool and > > spoil the part. > > > > From what I've read so far the LinuxCNC system only uses the index pulse > when it starts a sequence that requires synchronized motion. The G > command for threading sets a flag that tells the system the next time it > sees and index pulse to clear the counter and then it cancels the flag. > The G command doesn't restart it. At this point the A/B are tracked for > direction based on the other operations generated by the G command. > > The MESA cards, AFAIK, use a rising edge to trigger this index. After > that they don't care how long the level is or when it drops. Most > interrupts into processors work the same way. The edges are usually > qualified by the processor or system clock so it might check it a few times > that it stayed high for 100 nS before it registers as a rising edge. > > So if you think you are missing pulses first I believe the HAL Scope might > be able to see it. If it doesn't then you need a real scope. Depending on > the hardware it may well need full differential signals in order to deliver > the pulse into the hardware. > > John > > > > > Thanks as always! > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
