The encoder on this motor (btw it would help A LOT if you would indicate type of motor and/or link to a datasheet) is a so-called quadrature encoder. These encoders deliver pulse trains on two channels which have a phase shift of 90 deg. With these "shifted" signals, you can also detect the direction of movement. I think there should be some NI application notes covering the properties of quadrature encoders - such as
http://www.ni.com/gettingstarted/setuphardware/dataacquisition/quadratureencoders.htm
However, these encoders usually are not used with a signal conditioning circuit but with a decoding circuitry to detect the phase shift between channels. You probably can do this by software using two digital input channels. I have absolutely NO experience with LabView but I think there should be LabView applications avaiable for detecting quadrature encoder signals.
These encoders usually have a third "channel" which gives just one pulse per revolution and is used to detect a reference position precisely. You have to connect this channel only in case you need this feature.
