On Saturday 01 December 2018 22:30:28 Gene Heskett wrote: > On Saturday 01 December 2018 21:11:52 Thaddeus Waldner wrote: > > While I see that I need to get better at asking questions because I > > didn’t quite get an answer to what I was really asking, I do > > appreciate your insight into “Star grounding.” I have made a mental > > note of it and actually, all of my components installed thus far are > > grounded at a single point. Thank you. > > > > Now what I really want to know is, in the case of multiple DC power > > supplies, is it advisable to connect the negative terminals of each, > > and are there any pitfalls in doing that? For example, can I connect > > the negative terminals of the 5vDC supply and the 24vDC supply to > > the 7i96 isolated input common terminal? I believe I incorrectly > > called the negative terminal the ground earlier. > > > > I agree with your point on not homing stepper motors by banging them > > against a hard stop. However ... The Teknic ClearPath are not > > stepper motors. They are brushless DC servo motors with an > > integrated motor driver and encoder. They have a controller that can > > auto-tune the motor to the mechanical system ... . The SK models > > are designed to be drop-in replacements for stepper motors, complete > > with step/direction input signals and programmable steps per > > revolution setting. They also have sensorless homing. This feature > > drives the axis at user-defined speed and torque limit against an > > axis end stop. The home position is repeatable to within one count > > of the internal encoder (11,500CPR, I believe). The motor controller > > stays alive and tracks the encoder, even when the main DC supply > > (75v) is cut. It does this via an auxiliary 24v supply. > > I see. > > > My machine does have end limit switches installed. I just think the > > way the ClearPath does homing ought to be more repeatable. > > > > Now, is there a “home command” signal that I can connect to the > > enable signals of my ClearPath motors in order to sequence the > > homing routine? > > See "man 9 motion", as I'm sure it has both a home command and a home > in progress tally for each axis. You may even find a home input that > you could drive with a one shot timing out after the power supplies > are up and stable to make it automatic on power up. But I'd have to > worry about the safety aspects too, like what happens if somebody gets > hurt by the unexpected machine motion. > > I wouldn't look for a home command signal, but a "home completed" from > each axis. For that I expect you would have to ask the drive maker. I > expect it exists but they may have a different name. Be sure and get > the location of that terminal on the drive. Better yet the complete > manual for the drives, so you'd have it next time there is a question. > > > Thaddeus Waldner > > > > ________________________________ > > From: Gene Heskett <[email protected]> > > Sent: Saturday, December 1, 2018 3:52 PM > > To: [email protected] > > Subject: Re: [Emc-users] 7i96 step-direction headers > > > > On Saturday 01 December 2018 14:32:54 Thaddeus Waldner wrote: > > > I do have plenty of isolated inputs and outputs for that and my > > > plan was to use those. But as I got to wiring it up, I thought it > > > would be really neat to hook up all wires from each motor cable to > > > their respective stepgen headers. This isn’t possible, I see… so > > > back to the initial plan. > > > > > > As a related question, what is the prevailing wisdom on working > > > with multiple power supplies? Is it OK or advisable, for example, > > > to tie the ground at the stepgen on header to the common pin on > > > the isolated inputs, together with the ground for my 24v power > > > supply? > > Its apparently ok to common the - rails of multiple power supplies to this bolt. I am doing it. However with the inputs opto-isolated where steppers are used, it should be permissible to connect the psu's terminal only to the motor - terminal of the driver. What effect this might have on induced noise I have not observed. In that case, I'd mount the drivers on nylon so as not to punch thru the heat sink insulation under its hexfet output transistors.I do use shielded cable, shield connected only to that common bolt, and cut off inside a small diecast box glued to the side of the motor. Connecting the shield drain at the motor end of the cable would create a ground loop, and would be considered bad dog, no biscuit. :)
[snip star ground sermon] > > > And a related question… > > > > > > I need to have individual enable and drive feedback signals > > > because I am using the hard stop homing feature of the Clearpath > > > drive (drive backs the axis into a hard stop and sets that as > > > home) > > > > This is not the most accurate way to do that when microstepping the > > drives. So do use switches, located enough full steps from any hard > > stop that it never touches the hard stop. > > > > > and I need to > > > control the order in which homing happens. The way it works is, > > > when configured to use hard stop homing, the drive will home when > > > power is applied and the enable signal is high. Once motion stops, > > > the feedback signal goes high, at which point I would home the > > > next axis in the order. > > > > LCNC does that automaticly normally, just set the HOME_SEQUENCE > > numericly in the order desired, starting with zero. But its a > > manually performed operation from the gui. It skips any axis if that > > axis is set to a -1. > > > > > I suppose I could simply wire the feedback signal into the home > > > switch to take care of the inputs. Is there a HAL signal that I > > > can wire to the enable pins, perhaps with some sort of latching > > > device? > > > AIUI, motion remembers that state, it is why you get a requester are you sure, if rehoming w/o restarting. > > > Thanks! > > > > > > > On Dec 1, 2018, at 8:40 AM, Peter C. Wallace <[email protected]> > > > > wrote: > > > > > > > > On Sat, 1 Dec 2018, Thaddeus Waldner wrote: > > > >> Date: Sat, 1 Dec 2018 03:52:12 +0000 > > > >> From: Thaddeus Waldner <[email protected]> > > > >> Reply-To: "Enhanced Machine Controller (EMC)" > > > >> <[email protected]> > > > >> To: "Enhanced Machine Controller (EMC)" > > > >> <[email protected]> Subject: [Emc-users] 7i96 > > > >> step-direction headers > > > >> I am using TTL step-direction outputs on the 7i96 I/O board to > > > >> drive a Teknic ClearPath motor. With the board set to TTL mode, > > > >> is it possible to address the step- and dir- pins. I would like > > > >> to use one for an enable output for the motor and the other for > > > >> the feedback from the motor (input). > > > >> > > > >> Thaddeus Waldner > > > > > > > > No, the + and - step and direction pins are inverted copies of > > > > the same signal. You can as Andy suggests limit the number of > > > > active stepgens in the hal file and then use the freed step/dir > > > > pins as outputs (they can not be used as inputs) > > > > > > > > You should also be able to use one of the 7I96s isolated outputs > > > > to drive the enable (one output could perhaps drive all enables) > > > > > > > > Likewise you should be able to use the isolated inputs for drive > > > > feedback (and if these are used to signal a drive fault you can > > > > also parallel them if they are normally off or series connect > > > > then if they are normally on so be able to use a single input to > > > > monitor all drives) All my table movers are pure steppers, but you have devices that are better called servo's, and I have no experience with servo's other than using 2 of the Pico PWM-SERVO amps as spindle drivers, which do an exemplary job of over driving a 1hp rated motor into the about the 2hp range. One is a 1hp treadmill motor transplanted into a 7x12 where it can easily damage headstock parts if I don't profile the turn around to slow it for a g33.1 when its being used in a hand coded peck cycle. I also have some extra stuff in the hal file to measure the amount of overshoot as a way of assuring I don't hit the bottom of a blind hole and break off the tap inside the work. The other is driving the 90 volt, 9.7 nameplate amps 1hp, the oem motor in a G0704 grizzly mill, with a 126 volt power supply, and a 16 amp current limit. Thats accell profiled too but can still do a reversal at 3000 spindle revs to 3000 the other way in way less than a second. In both cases I can hear a short chirp from the motor as the PWM-servo hits its current limit. This isn't a recommendation, its much more of an I'm getting away with it observation. There would come a point where the PM field magnets in either motor could be weakened, but the motor folks don't share that information and I've apparently not hit that point (yet) at 16 amps. :) Take care, Thaddeus Waldner. -- 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
