The Laureate Model FRR can apply arithmetic functions (+, -, /, x) to two independently scalable pulse input channels, A and B. For example, it can add two flows (A+B) for total flow, subtract two flows (A-B) for net flow, take the ratio of two rates (A/B) to control mixing, or compute draw (A/B-1) to display net elongation of material between rollers. Pulse rates can be from 0.05 Hz to 1 MHz.

Ratio allows multiple flows to be mixed in a predetermined ratio in continuous mixing processes. Ratio can also 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 meter is used to monitor the ratio of flow rates, and a second meter to monitor the resulting batch totals.

Draw, which is obtained by subtracting 1 from ratio, is used to measure the elongation or shrinkage of material as it passes between rollers, or to monitor variation in the speed of rollers for tensioning.

In flow applications, the sensing element is normally a turbine flow meter, which outputs pulses at a frequency proportional to flow rate. The meter's arithmetic capabilities can be applied to either rate or totalized rate (delivered volume).

To determine rate, the Laureate FRR first determines frequency with quartz crystal accuracy by taking the inverse of the period between pulses, and then multiplies this frequency by a user-programmed scale factor. For rate measurements, the pulse rate can be from 0.05 Hz to 1 MHz. Square extraction is standard.

The Laureate FRR can also display rate, totals, and arithmetic combinations of channels A and B for non-flow applications that utilize a transducer with a pulse output. For example, the unit can display linear speed by timing pulses from a proximity switch for either channel, display total length by integrating these pulses, and combine rates or totals for the two channels.

The Laureate FRR is designed to operate with a wide range of pulse inputs. Exceptional flexibility is provided by the unit's universal dual-channel signal conditioner, which can accept magnetic signals from 12 mV to 250 Vac as well as signals from proximity switches with a PNP or NPN output, TTL or CMOS logic, and contact closures. Jumper selections provide optimum operation for different sensor types and noise conditions.

A built-in isolated 5, 10, or 24 Vdc excitation supply is standard to power proximity switches and other sensors. Options include dual relays for control or alarm, isolated 4-20 mA and 0-10V analog outputs, and an RS232 or RS485 port for data communications with a host computer or PLC. Modbus RS485 is fully supported.

The base price is $270. For more information and pricing of options, visit www.laurels.com/ratio.htm