Alfred Smart wrote: > I posted last week about steeper motors maybe week? > So I thought I would follow up and ask some more questions. > Anyway I was using terminal #7 on the gecko 210 tied to my estop to > ground to disable the drive. > This pulls the motor windings to zero, (gecko doc,s) > I always wonder why the drives were noisy and so were the motors. > as I ran the machine more and more, the motors would quit down and run > graet with no missed steps after about 5 min. or so. > I disconnected terminal #7 and the problem was fixed. > Anyone with any ideas what demons were at work here? Yes. You need a multi-pole relay, so you can use one pole for each Gecko drive. There are large current pulses flowing through the motor supply ground terminal as the drive switches each winding on and off. Due to the resistance and inductance of the wires connecting all these motor supply grounds together, they are not really held at the same voltage. You'd be amazed at the voltage that can be induced in a short length of heavy wire by these fast-rise current pulses, even 20 V or more can be seen. If you have even 6 V difference between two of the Gecko drives, then one drive can be enabled while another is disabled. So, you need to have no common connection between the drives, other than the motor supply wires. If your estop circuit de-energizes the relay coil when in Estop mode, then use a normally-closed contact for each Gecko. When the relay drops out, it shorts pin 7 to 12 on the same drive only. Use a 4PDT relay for up to 4 axes.
If you want to know why things quieted down after 5 minutes, it may be the FETs warmed up and their conductivity decreased. Jon ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
