I should probably start a new thread here but there is definitely a similarity in the noise problem.
In my jet 9 x 20 conversion I was getting lots of noise spikes on my spindle encoder feedback to the 7i78 card. I went through all the regular suspects, grounding, shielding twisted pair etc. with little or no change. On a "real" scope I was watching the noise spikes as vertical lines superimposed on the encoder A and B square waves. The noise was there even if the spindle was NOT turning and when the spindle motor controller was OFF. I started turning off things to see if the noise was from an external source such as the monitor or computer's switching supply. I even disconnected the DB-25 to the computer and supplied the 7i78 from a linear supply.....No change. Then I wondered what would happen if I turned off the G320 servo drives. I pulled the error/reset connections on the G320's and the noise went away. When I hooked the error/reset lines back up to one of the G320's and decreased the horizontal sweep on the scope to 10 microsec per division I got a beautiful rock solid 2 volt burst recurring every 50 microseconds and ringing for about 10 microseconds. My noise source is the G320's PWM generator which switches at 20 khz. I'm still not sure how such a horrible noise signal gets from the 48 volt motor armature switching circuit in the G320 to the input of the 7i78 but at least now I know the source and can try to fix it. I'm pretty sure that I can't just put a cap across the armature outputs of the G320 because that does bad things to the H bridge. Has anyone else experienced the PWM switching noise of their drives getting into their signal level circuits? If so, how did you deal with it? Thanks, Cecil ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today. http://sdm.link/xeonphi _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
