Laurel Rate Meter & Totalizer with Functions A+B, A-B, AxB, A/B, A/B-1

Arithmetic functions A+B, A-B, AxB, A/B, A/B-1 applied to channels A & B are a capability of Laureates with an Extended counter main board and FR dual-channel signal conditioner board. These function are applicable to rate or total after scaling to engineering units. The following are application examples:

• Add two flows (A+B) for total flow or total volume.
• Subtract two flows (A-B) for net flow or net volume.
• Take the ratio of two flow rates (A/B) for chemical mixing.
• Take the ratio of RPMs or belt speeds (A/B) to synchronize moving machinery.
• Subtract 1 from ratio (A/B-1) to control elongation of material compressed by rollers (draw).
• Multiply belt speed by weight of material on the belt to for rate or weight of material delivered by the belt. A weight transducers with frequency output is required.

Ratio and draw are similar, except that 1 is subtracted from ratio to obtain draw. The frequency of channels A or B is measured and converted to rate in engineering units by multiplying it by the appropriate scale factor for that channel. Either rate can be displayed. The A/B ratio is taken mathematically by the meter, and 1 is subtracted for draw. The result can be multiplied by a multiple or 10 from 0.0001 to 100000, and the decimal point can be set to display the result with the desired precision up to six digits.

Fast, High Resolution Measurement. Laurel counters determine frequency by timing an integral number of periods over a programmable gate time. The inverse period approach allows greater accuracy and faster update times than conventional meters which count signal pulses over a specified time interval. Channel A accepts pulses from 0.005 Hz to 1 MHz, while Channel B accepts pulses from 0.005 Hz to 250 kHz. At the minimum gate time of 10 ms, update rates can be up to 25/second. Such fast response is ideal for peak capture and for alarm and control applications. Variations in the displayed reading can be reduced by selecting a longer gate time. An adaptive digital filter can further reduce variations due to noise while rapidly responding to actual changes in the signal.

 

The Laurel dual-channel signal conditioner accepts inputs from proximity switches with PNP or NPN output, TTL or CMOS logic, magnetic pickups, contact closures, low-level outputs from turbine flow meters down to 12 mV, or high-level AC line inputs to 250 Vac. Jumper selections provide optimum operation for different sensor types and noise conditions. A built-in isolated 5, 10, or 24 Vdc excitation supply can power proximity switches or other sensors, and eliminate the need for an external power supply.

• 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
• Update rate to 25/s
• Isolated 5, 10 or 24 Vdc excitation supply to power sensors
• Universal AC power, 85-264 Vac
• NEMA 4X, 1/8 DIN case

• Serial communications: Ethernet Interface, Ethernet-to-RS485 converter, USB Interface, USB-to-RS485 converter, RS485 interface (dual RF11), RS485 Modbus interface (dual RJ45), RS232 interface.
• Low voltage power: 10-48 Vdc or 12-32 Vac
• Relay outputs: 2 or 4 relays, contact or solid state
• Analog output: Isolated 4-20 mA, 0-20 mA, 0-10V, 10 to +10V