4-20 mA Current Output Transmitter for Frequency, Rate or Period Input

• Inputs from NPN or PNP proximity switches, contact closures, digital logic, magnetic pickups down to 12 mV, or AC inputs up to 250 Vac.
• Internal conversion of input to six-digit reading:
  • Digital span adjust from 0 to ±999,999
  • Digital zero adjust from -999,999 to +999,999
• Output resolution: 0.0015% of span (16 bits)
• Output accuracy: ±0.02% of span
• High update rate
• Square root extraction standard
• 5, 10 or 24 Vdc excitation supply
• DIN rail mount housing only 22.5 mm wide
• Plug-in screw-clamp connectors
• Easy setup with PC-based Instrument Setup Software
• 5V, 10V or 24V dc sensor excitation output, isolated
• Dual solid state relays for alarm or control, isolated
• RS232 or RS485 serial communications, isolated
• Universal AC power, 85-264 Vac
• Priced at only $235 (basic pulse input transmitter)

• Extended Main Board for rate and total simultaneously, custom curve linearization, arithmetic functions A+B, A-B, AxB, A/B, A/B-1 (draw).
• Low voltage power, 10-48 Vdc or 12-32 Vac.

The Laureate 4-20 mA transmitter for frequency, rate or period accepts 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, 0-20 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 16-bit (65,536 step) digital-to-analog converter (DAC) for 0.02% output accuracy.

The update rate of the transmitter 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.

Standard features of Laureate transmitters include: