Intro4u2u

Laureate 4-20 mA output, pulse input frequency, rate and period transmitters accept two independently scalable input channels from a wide range of pulse sources, such as NPN or PNP proximity switches, contact closures, digital logic, magnetic pickups down to 12 mV, or AC voltages to 250 Vac. Input frequencies can range from 0.005 Hz to 1 MHz. The transmitter output can be selected as 4-20 mA or 0-10V and is isolated to avoid ground loops. Applications include AC line frequency, RPM or speed from proximity switch inputs, and flow from turbine flow meter inputs.

• With a Standard Main Board, the transmitter output can be scaled to track frequency in Hz, rate (such as gallons per minute), or period (inverse of frequency). Square root extraction is standard.
  

• With an Extended Main Board, the transmitter output can track rate or totalized rate (such as gallons) whether the transducer output is linear, requires square root extraction, or requires custom curve linearization. The latter can be provided by a curvilinear spline fit with up to 180 data points. The transmitter can also count up to a preset total or down from a preset total to zero. Such applications typically make use of optional dual solid state relays, which are available as options. External reset of totals is via a special three-position screw terminal connector. The two input channels A & B can also be combined arithmetically to provide an analog transmitter output that tracks A+B (e.g., sum of two flows), A-B (e.g., difference of two flows), AxB (e.g., horsepower as product of force and RPM), A/B (ratio of two flow), and A/B-1 (draw or relative elongation of material between rollers).

Exceptional Accuracy and Stability

Laureate pulse input frequency and rate transmitters determine frequency by taking the inverse of period as measured with a calibrated quartz crystal time base. This results in extremely accurate and stable 6-digit internal readings (±999,999 counts), which are then processed in software. The analog output is generated by an ultra-linear 12-bit (4096 step) digital-to-analog convert (DAC), whose output span can be adjusted from 0 to ±999,999 counts and zero can be adjusted from -999,999 to +999,999 counts. The analog output has a rated accuracy of ±0.05% of output span.

The update rate of the analog output is a programmed gate time + 30 ms + 0-2 signal periods. For a 60 Hz signal, the update rate would be 20 per second. Such fast update rates are ideal for alarm and control applications.

Transmitter programming is via a three-terminal RS-232 port using Laurel’s PC-based Instrument Setup Software. This software can be downloaded from this website at no charge. The required transmitter-to-PC interface cable is available from Laurel (P/N CBL03).

The transmitters are housed in a DIN rail case that is only 22.5 mm (0.89″) thick. Signal connections are via detachable screw clamp plug connectors.