On Friday 01 May 2020 22:19:57 andrew beck wrote: > I found this explanation of what a push pull output is.. > > https://www.dynapar.com/knowledge/encoder_output/ > > still doesn't make that much sense but I am sure it will all come > together. > > On Sat, May 2, 2020 at 2:14 PM andrew beck <[email protected]> wrote: > > Hi guys > > > > me again > > > > I have just received my schiender vfd encoder card from ebay for my > > spindle encoder feedback to linuxcnc
That card has inputs labeled +, - cos and +, - sin. So its expecting signals from a resolver, not an 1000 ppr encoder, which is not at all compatible with any 1000 ppr digital encoder regardless of its possible differential outputs in the digital domain. To receive and decode the 1000 line encoder you will need a "quadrature" encoder which will also have that missing index pulse. A resolver is an analog device consisting of an exciter winding driven from the +- ref terminals on that card, and which induces a voltage in two crossed at 90 degree coils such that the induced voltages coming back to the cos and sin terminals can be measured, and the actual position calculated from that, returning the position in degrees or radians, and zero degrees then is usually considered the index. But you could drive either to any position a tool changer might need. Most would drive it past that point a few counts, drop a pawl to stop it and back it up against the pawl to get the position accuracy needed. Its more accurate in that the answer is never quantized into 1/4000 of a turn which is what the 1000 ppr encoder would do. Depending on the electronics, the resolver could be slightly slower settling, and its always more expensive. > > I was just looking at it and it seems the encoder card only has > > differential A and B inputs- It doesn't have a index counter. > > > > obviously to make the spindle orientation work I need to be able to > > read the index pulse from the encoder. I was thinking maybe the > > best way to do this would be to get a ENCY mesa board and connect my > > encoder to that. then connect the one of the outputs from the board > > to linuxcnc encoder counters. the other split output can go to the > > vfd for closed loop control inside the vfd > > > > (I will only use the A and B pulses inside the vfd.) > > > > My vfd supports closed loop control if I have can get the encoder > > counting back into the vfd and I will get 200 percent of the full > > torque at 0 rpm which is pretty cool. It should be almost like a > > servo. > > > > does this all seem like a good idea to people? > > > > and has anyone ever used the ENCY mesa card? I am not sure how to > > power it. Eg do I power it from my mesa card encoder 5v or from the > > vfd . I guess I can't power it from both. > > > > this is the encoder card I have. needs to be used with a 12 v > > encoder. the max hz is 300khz which I calculated at 1000ppr allows > > me a max speed of 18000 rpm. I can get a 1000ppr encoder from my > > chinese servo supplier that allows up to 10k rpm which is what my > > max spindle speed is. and I think I can get a 12 v version. I am > > not sure what push pull outputs are though. > > > > > > https://www.se.com/nz/en/product/VW3A3405/encoder-interface-card-wit > >h-push-pull-outputs---12-v-dc/ > > > > > > and a pdf that shows the connections > > > > VW3A3405 ENCODER CARD > > <https://download.schneider-electric.com/files?p_enDocType=Instructi > >on+sheet&p_File_Name=1755538.pdf&p_Doc_Ref=1755538> > > > > regards > > > > Andrew > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
