You want to use NPN NC switches. This means that the circuit is energized when in normal condition. If the switch is made the circuit will open or if the power fails or if the wire breaks, the circuit will be open and hence you will detect the condition on the input. Oh and make sure it is the 3 wire type. The two wire type does not work well for our applications. I use the 12mm three wire type.
On 2014-02-22 11:12, Sven Wesley wrote: > I am going to shopaholic a bunch of proximity sensors to replace mechanical > homing and limit switches for two machines with Mesa cards (5i25/7i77) and > then it struck me, what is the best option? NPN or PNP? > How do they behave if there's no power to them or if they fail? For example > a PNP NO, is it open all the time or only open if the drive circuit has > power? What I am trying to grasp is what type of switch I should use to > trust the machine even if the switch fails (broken switch no operation). > > /Sven > ------------------------------------------------------------------------------ > Managing the Performance of Cloud-Based Applications > Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. > Read the Whitepaper. > http://pubads.g.doubleclick.net/gampad/clk?id=121054471&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Regards /Groete Marius D. Liebenberg +27 82 698 3251 +27 12 743 6064 ------------------------------------------------------------------------------ Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
