Modbus & Serial Output Transmitter for Ratio, Product, Sum or Difference of 2 Rates or Totals

• Two independently field-scalable pulse input Channels A & B
• Internal conversion of Channel A & B inputs to six-digit readings
  • Digital span adjust from 0 to ±999,999
  • Digital zero adjust from -999,999 to +999,999
• Applicable arithmetic functions: A+B, A-B, AxB, A/B, A/B-1 (draw)
• Frequencies from 0.005 Hz to 1 MHz
• Inputs from NPN or PNP proximity switches, contact closures, digital logic, magnetic pickups down to 12 mV, or AC inputs up to 250 Vac
• High output update rate
• 0-10V, 4-20 mA or 0-20 mA analog output, scalable, isolated
• Universal AC power, 85-264 Vac
• Priced at only $275 (basic arithmetic transmitter)

• Low voltage power, 10-48 Vdc or 12-32 Vac

The Extended Laureate Modbus & serial output, pulse input 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 to track the sum, difference, product, ratio, or draw of both input channels are available with the Extended main board. These arithmetic operations 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. This results in extremely accurate and stable 6-digit internal readings (±999,999 counts), which are then processed in software. Theupdate 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.

LTM Series serial output transmitters send data via an isolated serial port, which is user configurable for RS232 or RS485 and full or half duplex operation. 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 allows up to 31 Laureate devices to be addressed on the same RS485 data line. It is simpler than the Modbus protocol and is recommended when all devices are Laureates. It also allows use of Laurel Datalogging Software.

Standard features of Laureate transmitters include:

• Serial communications, isolated. User selectable RS232 or RS485, half or full duplex, Modbus or Laurel ASCII protocol.
• Analog transmitter output, 16-bit, user scalable and isolated. User selectable 4-20 mA, 0-20 mA or 0-10V levels.
• Dual solid state relays for control or alarm, isolated. Rated 120 mA at 130 Vac or 170 Vdc.
• Transducer excitation output, isolated. User selectable 5V@100 mA, 10V@120 mA or 24V@50 mA.
• Universal AC power supply for 85-264 Vac.

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).