On 08/23/2016 10:22 PM, Gene Heskett wrote: > On Tuesday 23 August 2016 22:13:55 Jon Elson wrote: > >> On 08/23/2016 04:09 PM, Gene Heskett wrote: >>> On Tuesday 23 August 2016 06:55:03 andy pugh wrote: >>>> For gear tooth detection you probably want >>>> http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l131 >>>> 3.T R0.TRC0.H0.XATS667.TRS0&_nkw=ATS667&_sacat=0 >>> 10 ordered, I'll figure out something to use the others for. 3 for >>> gear sensors and 6 for home & limits, leaves a spare. I'll need to >>> cobble up an index somehow. >> The ATS667 is a sensor to detect the passage of a gear >> tooth. It really is not designed as a proximity sensor. It >> will detect a ferrous item passing across the face of the >> sensor, but then stays in that state. If you check the >> datasheet, it has two sensors close together, compares the >> signal from them and sets a flip-flop for which one has more >> signal. So, it is designed to sense an object moving ACROSS >> the face of the sensor. >> >> Jon >> > So if we want to use it as home or limit, we should trip on the far side > of what we have passed? > > What occurs when it has come back from there? Or is at a great distance > from the trip generator? Or am I back to 59 cent roller microswitches? > I must admit, they do seem to be doing a quite repeatable job where I've > used them in essentially dry circuits. > > OK, so when a ferrous object passes left-to-right across the sensor, the output goes high, and then holds. When the object passes right-to-left, then the output goes low, and holds. The FF holds the state until the object comes back within range.
There most certainly are Hall sensors that detect the presence of an object, without the latching or directional features. I think that is really what you want. Also, sensors that have big magnets in them are not ideal in metal cutting machines. They are fine inside the head of my mill where chips shouldn't be able to get. Jon ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
