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Laurel Electronics provides
digital panel meters / controllers, totalizers, counters, loop-powered meters,
temperature meters, for all types of transducers or process indication &
control. |
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Laureate™
Scale Meter for Weighing Applications
High
accuracy weight, low cost, plus control outputs |
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Features |
| Setpoint
control with offset compensation for filling
applications. |
5-digit
resolution with scaling from 0 to 99,999. |
| Display
to 999,990 with fixed zero. |
Auto-tare
or manual tare, with tare value stored in
non-volatile memory. |
| Auto-zero
display function. |
Display
toggle between gross or net weight. |
| Count
by 1, 2, 5, 10, 20, 50 or 100 with rounding. |
Easy
scale calibration using known weight. |
| Isolated
10 Vdc supply to power up to four 350 ohm load
cells. |
AC
and DC input powered. |
| 4-
or 6-wire hookup. |
Up
to 60 conversions per second. |
| Green
or red LED display. |
NEMA
4X front panel, 1/8 DIN case. |
| Optional
dual relays, 4-20 mA & 0-10 V analog output,
RS-232/485 I/O, parallel BCD output, and low voltage
AC or DC power. |
Certified
to UL 3101-1, CAN/CSA-C22.2, EN 61010-1 (CE Mark). |
Click
to Order Scale Meter for Weighing Applications
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Description |
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The
Laureate™ Weight Meter is more compact and less
expensive than available alternatives. It provides a
choice of two signal conditioner boards: the
Laureate load cell signal conditioner board, which
provides full-scale ranges of 20, 50, 100, 250 and
500 mV with 4- or 6-wire load cell hookup, and the
Laureate DC signal conditioner board, which allows
the meter to accept preconditioned signals such as
0-10 V or 4-20 mA. Options include setpoint control,
analog output and digital communication boards. |
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| Display
& Setpoint Functions |
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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.
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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.
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Fixed
Zero. The display
can be shifted left to allow a fixed zero to be
displayed to the right. This allows values up to
999,990 to be displayed.
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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.
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Two
Tare Functions.
The weight meter offers two types of tare: 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).
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| Load
Cell Connection |
Easy
Scale Calibration |
Add-on
Functions & Options |
| The
load cell signal conditioner, which is normally used
with the weight meter, 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. The built-in
isolated 10 Vdc excitation supply can power up to four
350-ohm load cells in parallel. |
The
weight meter is normally set up 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 |
Plug-in
isolated analog output, dual setpoint controller and
RS-232/485 communications or parallel BCD output boards
can upgrade the Laureate weight meter to system interface
and control. |
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Fast
Response |
The
Laureate weight meter offers extremely fast read rates.
These are ideal for weigh-in-motion systems, setpoint
control, and computer interface applications. Concurrent
Slope (Pat 5,262,780) is a method of analog-to-digital
conversion that allows up to 60 conversions per second,
while integrating the input signal over a full 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 automatically select the best filter
setting for maximum noise rejection and minimum response
time. Control and interface outputs can be derived
from the filtered signal or, for quicker response,
from the unfiltered signal. Display of peak value
is standard in the Laureate series.
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Click
to Order Scale Meter for Weighing Applications
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Specifications |
| With
Load Cell Signal Conditioner |
Full-Scale
Input, mV |
Zero
Adjust |
Span
Adjust |
Error
at 25°C |
| ±20.000 |
-99,999
to
+99,999 |
0
to
±99,999 |
0.0030%
of
reading /°C |
| ±50.000 |
| ±100.00 |
| ±250.00 |
| ±500.00 |
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| With
DC Signal Conditioner |
Full-Scale
Input, mV |
Zero
Adjust |
Span
Adjust |
Error
at 25°C |
| ±200
mV |
-99,999
to
+99,999 |
0
to
±99,999 |
0.01%
FS
±1 count |
| ±2
V |
| ±20
V |
| ±20
mA |
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| With
Load Cell or DC Signal Conditioners |
| Accuracy,
Load Cell Signal |
Noise
Rejection |
Span
Tempco |
0.0030%
of reading/°C |
CMR,
DC to 60 Hz
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130
dB |
Zero
Tempco |
Auto-zero |
NMR
at 50/60 Hz |
90
dB with min filtering |
Calibration
Method |
2
points using zero weight and known weight |
-------- |
-------- |
| Accuracy,
DC Signal |
Display |
Span
Tempco |
0.01%
FS ±1 count |
Readout |
5
digits, 7-segment, 14.2 mm (.56") |
Zero
Tempco |
Auto-zero |
Color |
Red
or green LED |
Calibration
Method |
2
points using zero weight and known weight |
Range |
-99999
to +99999 or -99990 to +99990 (with fixed right-hand
zero) |
-------- |
---------- |
Rounding
Indicators |
Count
by 1, 2, 5, 10, 20, 50, 100 Four LED lamps |
| Power |
Excitation
Output |
Voltage,
std |
85-264
Vac and 90-370 Vdc |
5
Vdc |
5
Vdc ±5%, 100 mA max |
Voltage,
opt |
8-28
Vac and 9-37 Vdc |
10
Vdc |
10
Vdc ±5%, 120 mA max |
Frequency |
DC
or 49-440 Hz |
24
Vdc |
24
Vdc ±5%, 50 mA max |
Power
isolation |
Safety-rated
to 250 Vac, meter ground to earth ground,
DC to 60 Hz, 4.2 kVp per High Voltage Test |
Output
isolation |
50
Vdc to meter ground |
| Environmental |
A-to-D
Conversion |
Operating
Temperature |
0°C
to 55°C |
Technique |
Concurrent
Slope™ (Pat 5,262,780) |
Storage
Temperature |
-40°C
to 85°C |
A-to-D
Rate |
60/s
at 60 Hz, 50/s at 50 Hz |
Relative
HumidityProtection |
95%
at 40°C, non-condensingNEMA-4X (IP-65) when panel mounted |
Output
Update |
56/s
at 60 Hz, 47/s at 50 Hz |
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--------------- |
Display
Update |
3.5/s
at 60 Hz, 3/s at 50 Hz |
Click
to Order Scale Meter for Weighing Applications
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Weighing
the Load on a Truck |
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This
application illustrates some of the capabilities
of the Laureate weight meter. The single Laureate
can power all four 350 ohm load cells of the
scale with its 10 V, 120 mA isolated excitation
output. Six-wire connection eliminates the
effects of lead resistance and allows long
cable runs from the control room to the scale. |
The
five-digit meter can be scaled to display
truck weight up to 99,999 lbs with 1 lb resolution
or 999,990 lbs with 10 lb resolution. Accuracy
is 0.01% of full scale at 25ºC. To avoid the
effects of system-level noise, different filter
settings as well as "count by" of
1, 2, 5, 10, 20, 50 or 100 with rounding are
selectable.
To
read out net weight of the load, the truck
can first be weighed empty, and this weight
can be entered as tare at the push of a button
in an auto-tare mode. Or the nominal tare
value of the truck can be entered manually.
Display of net weight or gross weight is at
the push of a button. The gross weight and
net weight can be alarmed, be transmitted
to a computer via RS-232 or RS-485, or be
transmitted via a 4-20 mA analog signal. |
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Electrical
Connections & Setpoint Offset |
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In
4-wire connection, the
excitation and sense lines are tied together. The meter
can make ratiometric corrections for supply voltage
variations, but not compensate for variations in lead
resistance. This connection is often used with short
cable runs. |
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In
6-wire connection, the
sense lines are separate from the excitation lines,
thereby eliminating effects due to variations in lead
resistance. This allows long cable runs in outdoor environments
with temperature extremes. |
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The
DC signal conditioner board
can be utilized to accept preconditioned 4-20 mA or
0-10 V scale signals. In two-wire 4-20 mA transmitter
connection, the same two wires are used to apply voltage
and carry the output current. |
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In
a repetitive fill operation
(as illustrated by example), a setpoint offset of -50
will allow a shutoff setpoint to be set for 1000 and
actual shutoff to occur at 950 if it is known that 50
units will still flow following shutoff. An offset can
also be applied to emptying operations. |
Click
to Order Scale Meter for Weighing Applications
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FLW,
Inc - 3505
Cadillac Ave - Bldg E - Costa Mesa, CA. - 92626 - USA - Ph (714) 751 -
7512 - Fax (714) 751 - 0213
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