Normally, signals coming IN to the PC connect to J5 on the PMDX-122. This gives you 4 input signals - parallel port pins 11, 12, 13 and 15. If you already have signals attached to all four of these inputs, let us know which signals are connected where and perhaps we can recommend a way to reconfigure them to make room for the touch plate.
The function of the signals on J1, J2, J3 and J4 (parallel port pin 2 through 9) are controlled by jumper JP5 on the PMDX-122. If you are using ANY of these signals as output signals (i.e. step and direction), then ALL of these signals must be outputs from the PC, with JP5 set to the "out" position (the shorting clip on the center pin and the pin closest to the 26-pin ribbon header). In this case you cannot connect your touch plate to any signal on J1 through J4.
If you want to use pins 2-9 as inputs to the PC, and (presuming you are using Mach3) you have the PMDX-122 connected "Port #2" in the Config->Ports & Pins dialog, then you can remove the jumper from JP5 (or install it on the center pin sticking out to the side of the jumper so that it only contacts the center pin). This makes pins 2-9 inputs to the PC. See the PMDX-122 User's Manual section 3.1.4 for more information. This also means that none of the pins 2-9 can be outputs to drive step and direction signals to your motor drivers.
Bob
