Measurement Computing DBK Part 2 - Manual (Page 112)

Overview
Features of the DBK55
The DBK55 can be used for diverse frequency-monitoring applications. Typical uses include measuring
the flow of liquids with a flowmeter and measuring rotation (rpm) with a shaft encoder. The monitored
process must generate a series of electrical pulses whose frequency is related to the desired variable.
Features of the DBK55 include:
• Inputs can be analog (high or low level) or digital.
• Each channel has a programmable frequency range.
• Noise effects can be minimized by debounce, attenuation, and low-pass filtering.
• Up to 32 DBK55s can be used with a single LogBook or Daq device for a maximum of 256
channels.
The digital-to-analog converter (DAC) outputs a voltage from -5 V to +5 V to correspond with the selected
frequency range. The DaqBook directs the DBK55 module’s DAC to convert the data from the proper
input channel.
DBK55 Block Diagram
As indicated in the next figure, the DBK55 module completes the following functions for each channel:
• Conditions an input signal
• Selects the signal’s rising or falling edge
• Debounces the edge
• Measures the signal’s frequency.
• Sends a voltage (V
out
) analog signal [which corresponds to the measured frequency] from the DAC
to the primary data acquisition device.
These functions are discussed in the upcoming text.
DBK55 System Functionality
DBK55, pg. 2 988793 DBK Option Cards and Modules