DATEL, Inc., Mansfield, MA 02048 (USA)
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Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
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E–mail: [email protected]
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Internet: www.datel.com
DMS-20LCD-4/20 Series
Figure 1. DMS-20LCD-4/20 Series Simplified Schematic
Features
®
®
The DMS-20LCD-4/20 Series produces the lowest loop voltage-drop of any compa-
rably priced, 4-20mA input, 3½ digit LCD-display process monitors: 1.8V typical, 2.0V
max. This super-low drop means its nominal loop resistance (burden) is less than 100
Ohms! All operating power is derived solely from the 4-20mA loop current—no separate
power source is required! The simple 2-wire hookup allows the DMS-20LCD-4/20 Series
to be connected
anywhere
in the loop
All decimal-point and range-change selections are made via a six-position DIP
switch featuring vibration-resistant, gold-plated contacts—there are no jumpers or solder
gaps to ever open or close. Both gain (span) and offset (zero) adjustments are per-
formed with precision, 20-turn potentiometers. Three different models are available for
unipolar, bipolar, and positive display reading applications. The DMS-20LCD-4/20’s DIP
switch and adjustment potentiometers can accommodate literally hundreds of different
input-current/output-reading combinations. And, connections to the current loop are made
via a reliable, two-position, screw-type terminal block.
The DMS-20LCD-4/20 Series’ subminiature package houses a large, 0.37"/9.4mm
high digits, LCD display that can be read in virtually all lighting conditions—including direct
sunlight. An optional bezel assembly, featuring screw fasteners and a rubber seal,
simplifies panel mounting and provides excellent resistance to environmental dust and
moisture. All these outstanding features combine to make the DMS-20LCD-4/20 Series
the perfect meters for OEM 4-20mA current-loop process monitoring instrumentation.
•••••
Super-low loop drop: 1.8V typical, 2.0V max.
•••••
Self-powered, no separate supply required
•••••
Unipolar, Bipolar, and Positive Reading
Models
•••••
Subminiature package—Less than 0.90”
behind-the-panel depth
•••••
Large, 0.37"/9.4mm high, sunlight-viewable
LCD display
•••••
Non-interacting gain (span) and offset
(zero) 20-turn potentiometers
•••••
DIP-switch selectable range and decimal
points
•••••
Hundreds of different input/readout
combinations
•••••
Vibration-resistant package; reliable
screw-terminal input connections
DATA
3½ DIGIT A/D
CONVERTER
DC/DC
CONVERTER
BAND-GAP
REFERENCE
CIRCUIT
DIP SWITCHES
ZERO
ADJUST
GAIN
ADJUST
1
2
3
CURRENT TO
VOLTAGE
CONVERTER
+5V
–5V
DP3
DP2
DP1
R3
R7
1
2
TB1
LOOP INPUT
5
6
1
1
1
2
2
2
3
4
5
6
3
3
4
4
5
6
ON
ON
ON
–
+
4-20mA Input Loop-Powered
Ultra-Low 1.8V Loop Drop, 3½ Digit
LCD-Display Process Monitors
Actual Size
www.datel.com