I'm bringing up my mini-mill and have encountered a weird problem: I'm trying to use pins 10, 11 & 12 on the printer port as limit switch inputs for X, Y, Z axes, respectively, but the pins are acting like outputs. The limits switches are active high, with ether voltage dividers or diodes in line for level correction and short circuit protection. When I test the limit switches when not connected to the PC they work as expected. When connected to the PC a tripped a limit switch might cause the voltage to move by 0.5V or so, but the voltage is still held above the TTL high threshold.
The X-axis limit switch system consists of two OPB972 optical sensors (TTL level output), which have totem-pole output. Both are diode-ORed together with a 20K pulldown. The Y-axis limit switch system consists of two Honeywell 103SR12A-2 Hall sensors, which have active source outputs (Open emitter, 12V supply, ~12 volt active output, floating otherwise). Both are wired together and put through a 5.1K/2.2K resistor divider. The Z-axis limit switch system consists of two Parker Proprietary Hall sensors (TTL level output), which appear to have totem-pole outputs. As a precaution, I've diode-ORed them together with a 20K pulldown. I’ve got the following motherboard: ECS TIGT-I2(V1.0) Intel Atom D410 @ 1.66GHz BGA559 Intel NM10 Mini ITX Motherboard/CPU Combo http://www.newegg.com/Product/Product.aspx?Item=N82E16813135269 I’m running EMC 2.4.6. Any ideas? Do I just need lower impedance pulldowns? N.C. ------------------------------------------------------------------------------ Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
