On Saturday 29 December 2018 18:14:33 Peter C. Wallace wrote: > On Sat, 29 Dec 2018, Gene Heskett wrote: > > Date: Sat, 29 Dec 2018 17:34:48 -0500 > > From: Gene Heskett <ghesk...@shentel.net> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <emc-users@lists.sourceforge.net> > > To: emc-users@lists.sourceforge.net > > Subject: Re: [Emc-users] [utf-8] 7i77 ? Trying to understand TB2 > > > > On Thursday 27 December 2018 22:20:35 Greg Bentzinger via Emc-users > > wrote: > > . > > 7i77 ÿÿ Trying to understand TB2 > > > > Pin 1 ÿÿ VFIELD ÿÿ FIELD Power 8-32V > > Pin 2 ÿÿ VFIELD ÿÿ FIELD Power 8-32V > > Pin 3 ÿÿ VFIELD ÿÿ FIELD Power 8-32V > > Pin 4 ÿÿ VFIELD ÿÿ FIELD Power 8-32V > > Pin 5 ÿÿ VIN ÿÿ FIELD I/O Logic Power 8-32V > > Pin 6, 7 ÿÿ NC > > Pin 8 ÿÿ Ground ÿÿ COMMON > > > > So ÿÿ are pins 1-4 common to each other, not common and can be > > supplied different voltages, common but redundant to allow for > > greater current transfer. Everyone I have ask has given completely > > different and conflicting answers. Since I have no idea what the > > encoder current draw will be I will be supplying TB1 with its own 5V > > powersupply and thus W1 will short the 2 pins on the right (farthest > > from the DB25) I have a second 24V powersupply which I have wired to > > each pin 1-5 with ground on pin 8. My notes show I did this wiring > > 12/3/17 and have yet to actually power it up as have yet to obtain a > > clear definitive answer as to if this is proper or a potential smoke > > machine. > > > > Greg > > To further confuse the issue with my 7i76, it W1 is moved to the > right, no 5 volt feed goes there at all, the are several 5 volt inputs > on another terminal, so read that bit about moveing W1, and reread it > again. I think if a higher voltage field power is applied, it may be > only used for certain outputs. like 15 volts for controlling 12 to 15 > volt rated relays. That also implies the use of free wheeling diodes > on the relay coil to protect the boards chips so don't forget that. > > There is no logic power (5V) connection the the Field I/O part of the > 7I76 or 7I77. It is completely isolated from the 5V part of the board > so entirely depends on field power. VIN (that supplies the low voltage > regulator on the field I/O side) can come from a different source. For > most uses you simply leave W1 in the left hand position and supply > 8-32V field power. > > The output driver chips do not require flyback diodes unless you have > large loads (small relays etc dont need diodes but > solenoids/contactors do) > > The reason flyback diodes are not required for small loads is that the > outputs have a build in zener--> gate clamp that clamps the maximum > drain-source voltage to ~40VDC, basically slowing the MOSFET turn-off. > This works fine for small loads but does dump the stored inductive > energy into the MOSFET (If a flyback diode is used the energy is > dissipated mainly in the coil resistance)
Which is the better way speaking as a CET. If a relay hangs too long when being turned off, a few ohms in series with the diode to make some heat in the R will generally hasten the relays opening. But in the circuits I have assembled, the delay has been under 20 milliseconds, which for turning a motor off is close enough to instant for me. Rotor inertia will keep it spinning a lot longer than that. Now, with W1 moved to the right, the two terminals labeled field, tb5-6, have no continuity to anything else on the boards other terminals, so if I feed 15 volts to the field + input, can I assume that any output sent a logic one will cause 15 volts to appear on that output pin when measured from the - end of that 15 volts. Correct? And that setting that output to a logic zero will cause that output to be grounded to the field ground. Correct? And that it has no clue what a tristate state is? That leaves a question for Jon Elson then, which is, if I use one of those outputs as the 12 volt enable to your PWMServo amp, will that extra 2.5 to 3 volts hurt the PWMServo amp? It will get rid of a horrible shade tree kludge I have rigged up to get that 12 volts switch to work now. ================= new mill ==================== I went over to Lowes and got enough dexeon like stuff and a 2x4 sheet of 3/4 plywood to hang a shelf above the new mill, and dropped a caliper on the toy motors, finding they are indeed Nema 23's but short ones. I powered up the electronics box for 3 minutes, checked that the steppers were noticeably stiff, ran the spindle up to around 5 g's for 10 seconds or so, (no water rigged yet) more vibration than my air cooled version but only enough to notice. I haven't brought that atom computer down from the shop yet, nor the monitor/keyboard. Took a test fit with the shelf brackets on hand but will need something a bit smaller for the keyboard/mouse shelf on the end of this table. Not having any, and my back was yelping again, I hit the light switch and closed the door. Tommorrow is another day. And the last I knew, Wallies had shelf brackets. Getting close to yelling happy new year everybody. 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) 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
