Laureate Load Cell & Microvolt Digital Panel Meter
20 mV - 500 mV full-scale ranges, 4- or 6-wire connection
-20, 50, 100, 250 & 500 mV full scale ranges, 1 microvolt sensitivity
-Zero adjust from -99,999 to +99,999, span adjust from 0 to ±99,999
-Up to 60 conversions per second
-Isolated 10 Vdc excitation to power four 350-ohm load cells in parallel
-4 or 6-wire hookup to avoid lead resistance effects
-Universal 85-264 Vac power, or 10-48 Vdc / 12-32 Vac power
-Wide choice of options:
-2 or 4 relays, mechanical or solid state (isolated)
-Analog output, 4-20 mA, 0-10V, or -10V to +10V (isolated)
-Serial data I/O: Ethernet, USB, RS485, RS232 (isolated)
-Custom curve linearization, rate from consecutive readings
The Laureate™ load cell & microvolt meter is a high-sensitivity monitor and controller for use with load cells, strain gauges and microvolt input signals where high accuracy and stability are required.
DC microvoltmeter operation provides sensitivity down to ±20 mV full scale with 1 µV resolution. A display span of 99,999 counts with sensitivity of 0.2 µV per count can be obtained by applying a digital multiplier of five. A moving average digital filter assures quiet readings in electrically noisy environments.
Load cell operation allows six-wire hookup and scaling for direct readout in engineering units, such as pounds, kilograms or PSI. Scaling can be via front panel pushbuttons or a computer. Zero may be set from -99,999 to +99,999. Range may be scaled from 0 to ±99,999. Digital scaling and calibration eliminate drift caused by potentiometers in non-microcomputer based meters.
Meter accuracy is 0.01% of full scale ± 2 counts with an ideal load cell. Custom curve linearization, which is available with the optional Extended main board, can extend the working range of real-world load cells. Custom curve linearization also allows high accuracy to be achieved with lower cost, less linear load cells.
A built-in isolated 10 Vdc excitation supply can provide up to 120 mA of current at 10V to power four 350-ohm load cells in parallel. The meter operates in a ratiometric mode to eliminate errors due to supply variations. When excitation sense inputs are used in 6-wire connection, the meter compensates for variation in resistance of the transducer leads, thereby allowing long cable runs.
High read rates at up to 60 or 50 conversions per second while integrating the signal over a full power cycle are provided by Concurrent Slope (US Pat 5,262,780) analog-to-digital conversion. High read rates are ideal for peak or valley capture, real-time computer interface, and control.
Peak and valley values are automatically captured. These may be displayed via a front panel pushbutton command or control signal at the rear connector, or be transmitted as serial data.
Digital filtering is selectable for electrically noisy environments, including a batch averaging filter and an adaptive moving average filter which provides a choice of 8 time constants from 80 ms to 9.6 s. When a significant change in signal level occurs, that filter adapts by briefly switching to the shortest time to follow the change, then reverts back to the selected time constant. In a selectable Auto filter mode, the filter time constant is automatically selected based on detected signal noise.
Easy scale and offset are provided by Laureate DC, process and load cell meters by either of two selectable methods:
-With the coordinate reading method, the meter reads the high and low signal values, and the user enters the desired high an low reading values. The meter then calculates the span multiplier and offset. This method is ideal if an external calibration reference is available.
-With the manual coordinate method, the user enters the high and low input values in Volts plus the desired high and low reading values. This method is suitable if no external calibration reference is available.
Auto-tare is standard for weighing applications to subtract the weight of an empty container and may be controlled by an external pushbutton contact closure or a logic signal. Additional capabilities for weighing applications are provided by the Laureate weight & scale meter.
Designed for system use. Optional plug-in boards for communications and control include Ethernet and other serial communication boards, dual or quad relay boards, and an isolated analog output board. 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.