I read the data sheet and found this quote: " If the direction of rotation is reversed, so that the gear rotates from the pin 4 side to the pin 1 side, then the output polarity inverts."
Thanks for pointing out this device. It is NOT a simple Hall effect sensor. There are two hall effect sensors, the outputs of each are digitized and process with digital logic. There is quite a lot going on inside the device to make it easy to use. It self calibrates and works perfects down to zero RPM. Looks like it would be very easy to install on any lather of mill that had a metal gear on it as you don't even have to place it accurately, it will self-adjust the gain based on the distance from the gear. So the answer is the observer behavior is because the device is designed to behave that way. On Wed, Mar 9, 2016 at 10:30 AM, Kirk Wallace <[email protected]> wrote: > On 03/09/2016 09:38 AM, andy pugh wrote: >> On 9 March 2016 at 16:54, <[email protected]> wrote: >>> The issue is that we drilled about a .130 hole for the index but it acts >>> odd. If you rotate the spindle one direction it will pass the index and >>> stay high until it passes the hole then you get a little index pulse low. >>> If you run it the other direction it goes low after passing the index - and >>> you get a positive index pulse at every passing of the hole. >> >> This may be the internal logic at work. The sensors are rated to zero >> speed, and I think have an internal offsetting circuit. However I >> can't see how it can tell which way the gear is turning unless it has >> two sensors. >> Some automotive sensors do actively sense direction, and send a >> different pulse length in one direction compared to the other to >> encode the direction on a single wire. >> > > A very quick look at the datasheet seems to indicate that there are two > sensors about 2mm apart and that logic may use these to sense whether > the gear edge is metal to air or air to metal. I tend to agree with Andy > that the chip logic may be the problem. That and six bits may get you a > cuppa. > > > -- > Kirk Wallace > http://www.wallacecompany.com/machine_shop/ > http://www.wallacecompany.com/E45/ > > ------------------------------------------------------------------------------ > Transform Data into Opportunity. > Accelerate data analysis in your applications with > Intel Data Analytics Acceleration Library. > Click to learn more. > http://pubads.g.doubleclick.net/gampad/clk?id=278785111&iu=/4140 > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785111&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
