Laureate Scale Meter for Weighing Applications

• Easy scale calibration using known weight
• Setpoint control with offset compensation for filling applications
• Universal AC power, 85-264 Vac
• 6-wire load cell hookup or 4-wire ratiometric DC hookup
• Isolated 10 Vdc supply to power up to four 350 ohm load cells in parallel
• Up to 60 conversions per second
• Green or red display
• NEMA 4X, 1/8 DIN case
• Certified to EN 61010-1 (CE mark) and RoHS).

• Low voltage power: 10-48 Vdc or 12-32 Vac
• Dual relays: Form C contact or Form A solid state
• Analog output: Isolated, 0-10V, 4-20 mA or 0-20 mA
• Serial communications: RS232, RS485, USB, USB-to-RS485 converter, Ethernet, Ethernet-to-RS485 converter.

The Laureate™ Scale Meter is compact, inexpensive, and extremely accurate digital panel meter with special firmware for weighing applications. It is available with the Laureate load cell or DC signal conditioner board.

The load cell signal conditioner board accepts full-scale ranges of 20, 50, 100, 250 and 500 mV with 4- or 6-wire load cell hookup to display up to 99,999 counts. With 4 wires, the meter operates in a ratiometric mode to eliminate errors due to supply variations. With 6 wires, it also compensates for variations in transducer lead resistance, thereby allowing long cable runs in changing temperature environments. The built-in, isolated excitation supply can power up to four 350-ohm load cells in parallel at 10 Vdc.

The DC signal conditioner board can be jumpered for ratiometric strain gauge voltage ranges ±200 mV, ±2V or ±20V. With this board, a 20 mV strain gauge output can be scaled to display up to 10,000 counts, while a 200 mV output can be scaled to display up to 99,999 counts. Meter accuracy is 0.01% of full scale ± 2 counts.

• Setpoint offset. The ON/OFF setpoint control action can be programmed to occur with a specified offset. For instance, 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, an offset of -2.5 lbs can be programmed. The setpoint can then be set to 100 lbs, and the filling valve will be automatically shut off when the measured weight reaches 97.5 lbs.
• Count-by function. The weight meter can be programmed so that the display is rounded off to multiples of 1, 2, 5, 10, 20, 50 or 100. For example, if count-by 10 is selected, the meter will display 20 for an internal count of 15 to 24.
• Fixed zero. The display can be shifted to the left for a fixed zero to the right, allowing values up to 999,990 to be displayed.
• Auto-zero function. An auto-zero limit from 0 to 9 counts can be programmed to compensate for load cell drift. Whenever the meter comes to rest within that limit from zero, it will auto-zero. Entering 0 disables auto-zero.
• Two fare functions: auto-tare and manual tare. In auto-tare, an input line is grounded by an external pushbutton. This causes the current weight, which is normally the empty weight of the container to be stored in memory as an offset. In manual tare, the tare value can be entered manually via the front panel or a computer. For instance, the tare value may be the stated empty weight of a truck or rail car. Pressing the Reset button on the front panel toggles the display between gross weight (total weight on the scale) and net weight (gross weight with tare subtracted).

Easy scale calibration is achieved using a simple two-point calibration method. First, the desired LO IN reading is set to 0, and the desired HI IN reading is set to a desired value. With no weight on the scale, a button is pushed for LO IN. With a known weight on the scale, that button is pushed again for HI IN. The meter then automatically computes scale and offset for readout up to five digits in weight units.

Fast read rates to 60/sec are provided for weigh-in-motion systems, setpoint control, and computer interface. Concurrent Slope (Pat 5,262,780) is a method of analog-to-digital conversion which allows up to 60 conversions per second while integrating the input signal over a full AC line cycle.

An adaptive digital filter can be set for time constants from 17 ms to 9 s, yet responds rapidly to a change in input signal level exceeding a threshold value. The meter can also automatically select the best filter setting for maximum noise rejection and minimum response time. Peak and valley capture are standard.

Designed for flexibility. Plug-in isolated analog output, dual setpoint controller, and serial communications boards can upgrade Laureates from a simple monitor to system interface and control. Laureates may be powered from 85-264 Vac or optionally from 12-32 Vac or 10-48 Vdc. They are 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.