Frequency input module SCM5B45 Series

printed circuit board-mounted

Each SCM5B45 frequency input module provides a single channel of frequency input which is isolated and converted to a high-level analog voltage output (Figure below). The voltage output is logic switch controlled, which allows these modules to share a common analog bus without the requirement of external multiplexers. The frequency input signal can be a TTL-level signal or a zero-crossing signal. Terminal 3 on the field-side terminal block is the “common” or ground connection for input signals. A TTL signal is connected from terminal 2 to terminal 3, while a zero-crossing signal is connected from terminal 4 to terminal 3. Input circuitry for each of the signal types has hysteresis built in. An input signal must cross entirely through the hysteresis region in order to trigger the threshold comparator.