4-20 mA & Serial Data Output Transmitter for Ratio, Product, Sum or Difference of 2 Rates or Totals

This Laureate transmitter accepts two independently scalable input channels A & B 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.

Arithmetic functions A+B, A-B, AxB, A/B or A/B-1 are made available by the Extended counter main board and can track the sum, difference, product, ratio, or draw of both input channels. These functions can be applied to scaled rates, scaled totals, square root of rates, totals after square root extraction, custom curve linearized rates, or totals after custom curve linearization.

• Sum can be used to add two flows for total flow, or to add the number of parts carried by two conveyor belts.
• Difference can be used to subtract outflow from inflow for net flow, or to subtract reject parts from total parts.
• Product can be used to multiply two rates, for example to compute  horsepower by multiplying torque by RPM.
• Ratio can be used to compare flow rates in two channels, the RPM of rollers or gears, or the speed of moving machinery, such as conveyor belts. Ratio can also be applied to scaled totals to compare two batches to be mixed. In this application, one transmitter is used to monitor the ratio of flow rates, and a second transmitter to monitor the resulting batch totals.
• Draw is obtained by subtracting 1 from ratio. Draw is used to measure the elongation of material as it passes between rollers, or to monitor variation in the speed of rollers for tensioning.

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. Extremely accurate 6-digit internal readings (±999,999 counts) are processed in software.

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

Standard features of Laureate LT transmitters include:

• 4-20 mA, 0-20 mA, 0-10V or -10V to +10V analog transmitter output, isolated, jumper-selectable and user scalable. All selections provide 16-bit (0.0015%) resolution of output span and 0.02% output accuracy of a reading from -99,999 to +99,999 counts that is also transmitted digitally. Output isolation from signal and power grounds eliminates potential ground loops.
• Serial communications output, RS232 or RS485 (half or full duplex), jumper selectable. Three protocols are user selectable: Modbus RTU, Modbus ASCII, or Laurel ASCII. Modbus operation is fully compliant with Modbus Over Serial Line Specification V1.0 (2002). The Laurel ASCII protocol is simpler than the Modbus protocol and is recommended when all devices are Laureates.
• Dual solid state relays, isolated, for alarm or control. Rated 120 mA at 140 Vac or 180 Vdc.
• Transducer excitation output, isolated. User selectable 5V@100 mA, 10V@120 mA or 24V@50 mA.
• Universal 85-264 Vac power. Low-voltage 10-48 Vdc or 12-32 Vac power is optional.

Easy Transmitter programming is via Laurel's Instrument Setup Software, which runs on a PC under MS Windows. This software can be downloaded from this website at no charge. The required transmitter-to-PC interface cable is available from Laurel (P/N CBL04).