I actually wired all limit switches in series, (and like you, the negative X, and negative Y limits also serve as the Home switches for each). I never could get it to work with Mach. I ended up disabling the negative limit switch for each in Mach, (although they are still physically wired and positioned to function as limits). As you gain experience with your machine, you will quickly learn WHERE it's limits are physically located. The only real benefit of the limit switches, are the Home switches. So that you can establish WHERE the machine is actually located each time you start it up (and Re-Home the machine). During a Homing Cycle, the axis's are homed ONE AT A TIME. (Z first, then Y, and then X). Mach will move toward the home limit switch, until it strikes it, then back off just enough to un-trigger the switch on Each of the axis. Once homing is complete, subsequent limit switch strikes are interpreted by Mach to be a limit switch as being triggered, which causes Mach to STOP and trigger an error. I know how confusing it all can be, hope this helps you to get your machine up and running!