On Thursday 29 October 2020 06:20:22 andrew beck wrote: > hey everyone > > I have a fanuc velocity amp which I have hacked and found the 0-10v > speed reference input on it. the amp takes in 0-10v and Rev/FWD > inputs. this is ideal to control with a Pot and two switches and how > I am currently controlling it. On my cnc mill i used a 7i76 card and > the virtual pot and switches on the 7i76 work mint. > > I think the 7i77 is a bit different though and just wondering how to > best control the VFD > > I don't want to connect any grounds across to the 7i77 from vfd and > would prefer something like how the 7i76 works. eg just a POT and two > switches. just looking for info on how to best do this. I am open to > using relays etc. > > Regards > > Andrew
I am not useing a 7i77 since I'm mostly stepper, I'm using 7i76D's slaved to a 5i25, but I got the impression the spindle interface part of the 7i77 was identical. But since I'm also using Jon's pwm-servo to run a 1hp PMDC to around 2 hp on my G0704, I am not using the electronic pot for anything. And it works mint with a straight pwm feed. But over on the 6040, which has a 1hp 24k vfd controlled spindle, I am using the electronic pot to run the vfd and that works well including the direction. No pid or feedback since those motors are either synchro or very low slippage induction and don't need feedback to hold speed up to their torque limits. I think the spindle control of the 7i77 works the same, probably with only the card name changed in the hal file. Have you tried it? It ought to Just Work. And if the spindle is fitted with an encoder its only reason to exist is rigid threading, which the 6040 hasn't the torque to do anyway. No encoder on that motor. 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
