I am currently in the process of retrofitting a Shopbot PrsAlpha to work with Mach 4 and the PMDX-422, and I'm having trouble getting the limits to work right. The problem is that the Shopbot uses a single inductive sensor on each axis (which responds to a small metal assembly at each end of the axes). This means that there is not a distinct signal for X++ and X--, and the same goes for Y. I was hoping that Mach 4 would be able to discriminate between the positive and negative limits based on the current direction of movement, but this doesn't seem to be the case. Instead, when I set up the inputs for X++ and X-- as the same input pin on the PMDX, the software triggers both the positive and negative limits, and does not allow me to jog back within bounds. My current solution is to simply enable the X-- limit, and just use the limit override when it hits the positive limit (since it will read it as the negative limit and will not otherwise allow me to put it back within bounds). Of course this is not ideal, and I worry especially that others using the machine may be confused or override and move the wrong way. Any suggestions would be much appreciated!