On Friday, 1 April 2022 09:51:50 EDT Leonardo Marsaglia wrote: > Hi guys, I hope you're all doing well > > Quick question to define a little issue I have. I purchased a VFD that > I wrongly thought had a pulse train input for speed reference. Turns > out that feature it's optional so I need an additional card to have > it. By the way this Simphoenix E280/E580 VFD can reach more than 800 > hz so it's a good candidate for high speed spindles (which is the main > reason why I purchased it). > > So my question is: Is it that difficult to modify the firmware on the > 7i95 to add at least 1 PWM generator so I can easily convert that to > analog voltage? Because if not, I need to make a frequency to voltage > converter which is a little trickier. I prefer the PWM option of > course. > > Thanks as always for your help and knowledge :)
Have you actually tried to feed a software PWM into the analogue input? They are usually filtered well enough to do that by filtering to the average of a fast PWM. I have a huan yang clone on my 6040 I did that with for a couple months before I found we had an rs485 driver that worked even better. You may need to buffer that 5volt p-p signal in a transistor to bring the swing up to the 10 volts the vfd needs, but the vfd also can supply 12 volts to do that with. You'll need two transistors to keep from inverting the speed range, look up a long tailed invertor on google. Better yet, a ttl input cmos output AND gate, will give you a full rail to rail signal. Check the docs from the vfd, you may need to do the same with the dir signal. Generally both the run and dir signals are energized by pulling that input down to ground from its open circuit of 10 volts. Or use a Mesa SpinX1. I'm using that on my sheldon to do the reversal when rigid tapping in 1/4 turn at 100 spindle rpms. Response speed if the vfd is tuned correctly, is not a problem. Generally, they are not tuned "Out Of The Box". Take care and stay well Leonardo. 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, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
