If you route a signal to or from an external device, you might need to invert the polarity of the signal. For example, you may need to change a high gating signal to a low gating one or look at falling edges instead of rising edges. With routing in NI-DAQmx, you can invert a signal during the routing. If there is an inverter available along the route, the inversion of the signal takes place. Inversion could fail if an overlapping route has previously reserved the inverter with an incompatible configuration.