Laurel Electronics LAUREATE SERIES DPM - Manual (Page 34)

-32-
17. LOAD CELLS AND MICROVOLT INPUTS
This section provides setup instructions for use as a microvoltmeter or with load cells and strain
gauges. 10 Volt excitation will power up to 4 350 Ohm load cells. Sense leads may be used
to compensate for lead resistance of the excitation supply. For configuration of optional
boards, see the appropriate section elsewhere in the manual.
17.1 RANGE JUMPER LOCATIONS
Input Jumper Full Scale Display
Locations Scale factor = 1
20mV
e 20000
50mV a 50000
100mV b 10000
250mV c 25000
500mV d 50000
Notes 1. See Section 22 to select 10V excitation.
2. Jumpers are 2.5mm (0.1 in).
MENU KEY DIGIT SELECT KEY VALUE SELECT KEY
Press until Strn
(ratiometric) is displayed.
Press to select 20.0, 50.0,
100.0, 250.0 or 500.0mV Press the key to display
InPut (Input type selection).
17.2 MENU SELECTION
Figure 17.1 Load Cell Signal Conditioner
To scale the meter using the reading method of coordinates of 2 points, the low signal input and
high signal input are read directly by the meter and are stored as Lo in and Hi in. For example,
the full scale range of a load cell is 500 pounds and has an output of 2mV/V. With 10V excitation,
the full scale range of 20mV selected. The resolution is .01 pounds. With no weight on the scale,
the meter should read 0.00 and with a 500 pound weight on the scale the meter should display
500.00 pounds. With no weight on the scale, press the menu key to select Lo inand press the
digit select key. The meter will take readings and display the millivolt value of the input signal.
Pressing the value select key will store this reading as Lo in. Press the menu key to select Hi
in, place the 500 pound weight on the scale and repeat the procedure the same as for Lo in.
Press the menu key to select lo rd (Low reading) and enter 000.00, then press the menu key
to select Hi rd (High reading) and enter 500.00. Advantages of this method are accuracy, since
reading the value corrects for any error in the transducer, and ease of recalibration. To
recalibrate the meter, take readings at 0 and 500 pounds, Lo rd and Hi rd do not need to be
reentered. If a 500 lb. weight was not available, the same result can be achieved by using any
known weight. During setup, it may be necessary to enable some menu items. See Section
9 for further information. See Section 12, Process Meters, for an example scaling by direct entry
of the input values.
a
b c
d
e