Laurel Electronics LAUREATE SERIES 2 DIGITAL PANEL METER - Manual (Page 4)

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3. PRODUCT INTRODUCTION
Our digital panel meters are versatile, cost effective solutions to a wide variety of monitoring
and control applications. Depending on the choice of signal conditioner, they are easily set up
for an accurate display of temperature, pressure, flow, weight, voltage or current, all in
appropriate engineering units and with zero and span adjustment when needed. Setup can be
via front panel pushbuttons or the meter’s serial interface. Selective security lockout of the
front panel keys protects against accidental changes to meter setup.
High read rates up to 60 per second (50 for 50 Hz operation) are made possible by
Concurrent Slope Conversion (Pat 5,262,780), which integrates the signal over an AC power
line cycle for maximum noise rejection. High read rates provide accurate peak and valley
capture, and quick response for control applications. An adaptive digital filter supplies a time
constant for the encountered signal noise level, yet responds rapidly to changes that exceed a
selected threshold. Self-calibration occurs automatically after every 17th reading.
The standard power supply is a high-efficiency switching unit that operates from AC or DC,
and allows the meters to be powered from worldwide AC without changes. A low-voltage
supply is optional for power from 10-48V batteries or from 12-30 Vac. Both supplies provide an
isolated 5, 10 or 24Vdc transducer excitation output.
The meter case conforms to the 1/8 DIN size standard. It is made of high impact, 94V-0 UL-
rated plastic and is watertight to NEMA-4 (IP65) when panel mounted. Mounting is from the
front of the panel and requires less than 110 mm behind the panel. Power and signal wiring is
via removable plugs conforming to UL61010C safety standards. All output options are isolated
from meter and power ground to 250 Vac.
Extended meter versions can linearize nonlinear inputs. Up to 180 data points may be
linearized by a computer program that stores setup parameters in nonvolatile memory.
Extended meters can also display rate of change, for example to display flow rate based on
changing tank level.
Alarm or setpoint control is provided by an optional relay board with two or four Form C 8A
mechanical relays or two or four Form A 120 mA solid state relays. The setpoints may be
latching or non-latching, be energized above or below the setpoint, or operate in a fail-safe
mode. The relays can operate from the filtered signal to reduce relay chatter or from the
unfiltered signal for fastest response. Snubber circuits and a programmable relay switching
time delay extend relay contact life.
An isolated analog output of 4-20 mA, 0-20 mA, 0-10V or -10 to +10V can be provided by an
optional analog output board. The output is linearized to the display and can operate from the
filtered or unfiltered signal input. It can be scaled via front panel pushbuttons or the meter’s
serial interface.
Ethernet USB, RS232, or RS485 (2-wire half-duplex or 4-wire full-duplex) serial communi-
cations options are available with the Modbus protocol or a simpler custom ASCII protocol.
Modbus operation includes RTU or ASCII modes, up to 247 digital addresses, and up to 32
devices per RS485 line without a repeater. Ethernet-to-RS485 and USB-to-RS485 converter
boards allow a meter to be interfaced to a PC and to multiple meters on an RS485 network.
Meter programming can be via the meter’s front panel or a PC running Windows based
Instrument Setup Software (serial interface option required).