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).

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

Laureate 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.

Universal Signal Conditioner

Signal conditioner board for Laureate A/B Ratio & A/B-1 draw meterThe Laureate 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.

Other Features & Options

Optional plug-in boards for communications and control include Ethernet and other serial communication boards, dual or quad relay boards, and single or dual isolated analog output boards. Laureates may be powered from 85-264 Vac or optionally from 12-32 Vac or 10-48 Vdc. The display is available with red or green LEDs. The 1/8 DIN case meets NEMA 4X (IP65) specifications from the front when panel mounted. Any setup functions and front panel keys can be locked out for simplified usage and security. All power and signal connections are via UL / VDE / CSA rated screw clamp plugs.


  • Two independently scalable totals for Channels A & B
  • Arithmetic functions A+B, A-B, AxB, A/B, A/B-1 applied to rate or total
  • Inputs from NPN or PNP proximity switches, contact closures, digital logic, magnetic pickups down to 12 mV, or AC inputs up to 250 Vac
  • Frequencies from 0.005 Hz to 1 MHz
  • Universal 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac power
  • Transducer excitation output (isolated)
  • Wide choice of options:
    - 2 or 4 relays, mechanical or solid state (isolated)
    - 1 or 2 analog outputs (isolated)
    - Serial data I/O: Ethernet, USB, RS485, RS232 (isolated)


Readout 6 LED digits, 7-segment, 14.2 mm (.56"), red or green.
Display Range -999999 to +999999, XXXXEX notation beyond 999999
Zero Adjust -999999 to +999999
Span Adjust 0 to 999999
Indicators Four LED lamps
Types AC, pulses from NPN, PNP transistors, contact closures, magnetic pickups.
Signal Ground Common ground for channels A & B
Channel A Freq. 0.005 Hz to 1 MHz
Channel B Freq. 0.005 Hz to 250 kHz
Minimum Signal Nine ranges from (-12 to +12 mV) to (+1.25 to +2.1V).
Maximum Signal 250 Vac
Noise Filter 1 MHz, 30 kHz, 250 Hz (selectable)
Contact Debounce 0, 3, 50 ms (selectable)
Rate Accuracy
Time Base Crystal calibrated to ±2 ppm
Span tempco ± 1 ppm/°C (typ)
Long-term Drift ± 5 ppm/year
Voltage, standard 85-264 Vac or 90-300 Vdc
Voltage, optional 12-32 Vac or 10-48 Vdc
Frequency DC or 47-63 Hz
Power  consumption (typical, base meter) 1.2W @ 120 Vac, 1.5W @ 240 Vac, 1.3W @ 10 Vdc, 1.4W @ 20 Vdc, 1.55W @ 30 Vdc, 1.8W @ 40 Vdc, 2.15W @ 48 Vdc
Power Isolation 250V rms working, 2.3 kV rms per 1 min test
Excitation Output (standard)
5 Vdc 5 Vdc ± 5%, 100 mA
10 Vdc 10 Vdc ± 5%, 120 mA
24 Vdc 24 Vdc ± 5%, 50 mA
Output Isolation 50 Vdc to meter ground
Analog Output (optional)
Output levels 4-20 mA, 0-20 mA, 0-10V, -10 to +10V (single-output option)
  4-20 mA, 0-20 mA, 0-10V (dual-output option)
Current compliance 2 mA at 10V ( > 5 kΩ load)
Voltage compliance 12V at 20 mA (< 600Ω load)
Scaling Zero and full scale adjustable from -99999 to +99999
Resolution 16 bits (0.0015% of full scale)
Isolation 250V rms working, 2.3 kV rms per 1 min test
  (dual analog outputs share the same ground)
Relay Outputs (optional)
Relay types 2 Form C contact relays or 4 Form A contact relays (NO) 2 or 4 Form A, AC/DC solid state relays (NO)
Current Ratings 8A at 250 Vac or 24 Vdc for contact relays 120 mA at 140 Vac or 180 Vdc for solid state relays
Output common Isolated commons for dual relays or each pair of quad relays
Isolation 250V rms working, 2.3 kV rms per 1 min tes
Serial Data I/O (optional)
Board selections RS232RS485 (dual RJ11 or RJ45 connectors), USB, Ethernet, USB-to-RS485 converterEthernet-to-RS485 converter
Protocols Modbus RTU, Modbus ASCII, Modbus TCP (Ethernet), Laurel ASCII
Data rates 300 to 19200 baud
Digital addresses 247 (Modbus), 31 (Laurel ASCII),
Isolation 250V rms working, 2.3 kV rms per 1 min test
Operating temperature 0°C to 55°C
Storage temperature. -40°C to 85°C
Relative humidity 95% at 40°C, non-condensing
Protection NEMA-4X (IP-65) when panel mounted
Electrical Connections
Pinout of Laureate A/B Ratio & A/B-1 Draw panel meter


Application Examples
Controlling the Mixing Ratio of Two Fluids
Displaying and alarming the input flow rate ratio of two fluids (gas or liquid) allows these to be mixed in a predetermined ratio in continuous processes. The sensing element is normally a turbine flowmeter, which outputs pulses at a frequency proportional to flow rate. The A/B ratio can also be displayed for totalized rate (or delivered volume).
Computing Net Fluid Inflow & Outflow
The ratio of the inflow and outflow rates of a tank is a measure of the relative filling or emptying rate. The same meter can also be programmed to display the net inflow or outflow rate in flow units, or to display totalized inflow our outflow in volume units. Any of these parameters can be alarmed using the dual relay board and be transmitted via 4-20 mA, RS232 or RS485.
Controlling Coating Thickness on a Film
In this application, Channel A measures the rate at which a coating material is applied, as measured by a flow meter, while Channel B measures the speed of the film based on pulses from a proximity switch. Displaying and alarming the A/B ratio assures that an even thickness of coating material is applied as the speed of the film is varies.
Synchronizing Two Conveyor Lines
The dual-channel Laureate counter can measure the speed of conveyor lines by using the output of proximity switches which sense gear teeth or spokes of rotating drive wheels. Displaying the speed ratio of two lines allows line speeds to be adjusted so that material arrives at work stations when needed.
Measuring Draw for Elongation
Draw (Ch A / Ch B - 1) can be used to display the elongation of films compressed between rollers, the shrinkage films, and the RPM difference of rollers whose speed is varied to maintain tension. The six-digit resolution of the Laureate dual channel counter / rate meter is ideal for comparison of rates that are close to each other.
Datasheet, Manual, Mechanical and Serial I/O info.
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Rate Meter & Totalizer with Functions

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Tags: Panel Meter; Laureate; Laurel Electronics, High accuracy