I just set index-invert to TRUE and FILTER to false on the hostmot encoder parameters and until now it's not missing pulses anymore. I'll keep testing it to see how it goes.
El sáb., 21 mar. 2020 a las 1:21, Leonardo Marsaglia (<ldmarsag...@gmail.com>) escribió: > 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
