The P635 is a single-width, 3U, PXI bus module with eight frequency measurement channels. This counter module can be used to monitor a variety of pulse sources. Moreover, its unique circuitry allows the monitoring of a wide range of frequencies without changing any module settings. TTL inputs are provided as well as differential input circuits, with filtering and hysteresis to provide high noise immunity. The switching threshold is programmable. The input voltage should be at least twice the threshold voltage for noise immunity. AC or DC coupling of the differential inputs is programmable on a per-channel basis.
