The Laureate Model LW is a UL-listed, 5-digit panel meter with special firmware for scale / weighing applications. The unit provides a choice of two signal conditioner boards: a load cell signal conditioner with full-scale ranges down to 20 mV, and a DC signal conditioner for preconditioned signals such as 0-10V or 4-20 mA. With either signal conditioner, accuracy is ±0.01% of full scale ±1 count.

The Laureate LW offers extremely fast read rates of up to 60 conversions per second. Fast read rates are ideal for weigh-in-motion systems, setpoint control, and computer interface. An adaptive digital filter quiets the reading, yet responds rapidly to changes in level exceeding a threshold value.

The load cell signal conditioner is designed for 4- or 6-wire hookup. In 4-wire hookup, the meter operates in a ratiometric mode to eliminate errors due to supply variations. In 6-wire hookup, it also compensates for variations in transducer lead resistance, thereby allowing long cable runs in changing temperature environments. An isolated 10 Vdc excitation supply is built in and can power up to four 350-ohm load cells in parallel.

Special weighing firmware features include manual tare or auto-tare at the push of a button, auto-zero to compensate for load cell drift, a selectable count-by function of 1, 2, 5, 10, 20 or 50 to round off the display, and selectable setpoint offset. For example, if bags are to be filled to 100 lbs and the material delivery spout is known to hold and dispense an additional 2.5 lbs following shut-off, a setpoint offset of -2.5 lbs can be programmed. A dummy right-hand zero can also be selected so that weights up to 999,990 can be displayed.

The weight meter can be set up using a simple two-point calibration method, where a button is pushed first with no weight on the scale, and then with a known weight. The meter then automatically computes span and offset to display weight with up to five digits.

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 $250 with the DC signal conditioner and $305 with the load cell signal conditioner.. For more information and pricing of options, visit www.laurels.com/scalemeter.htm