DATEL, Inc., Mansfield, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
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, 3 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
D A T A
3 D I G I T A / D
C O N V E R T E R
D C / D C
C O N V E R T E R
B A N D - G A P
R E F E R E N C E
C I R C U I T
D I P S W I T C H E S
Z E R O
A D J U S T
G A I N
A D J U S T
1
2
3
C U R R E N T T O
V O L T A G E
C O N V E R T E R
+ 5 V
5 V
D P 3
D P 2
D P 1
R 3
R 7
T B 1
L O O P I N P U T
5
6
1
1
1
2
2
2
3
4
5
6
3
3
4
4
5
6
O N
O N
O N
+
4-20mA Input Loop-Powered
Ultra-Low 1.8V Loop Drop, 3 Digit
LCD-Display Process Monitors
Actual Size
Order on-line
at www.datel.com
2
DATEL, Inc., Mansfield, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
DMS-20LCD-4/20
3 D I G I T , L C D D I S P L A Y , 4 - 2 0 m A L O O P - P O W E R E D M E T E R S
Operating and Setup Instructions
Performance/Functional Specifications
Typical at T
A
= +25C, unless otherwise noted.
The DMS-20LCD-4/20, using any of the DIP-switch settings described above, can
withstand overcurrents, including those resulting from accidental reverse-polarity
connections, up to 40mA without sustaining any damage.
Because DATEL's DMS-4/20 loop-powered meters employ active circuitry to
convert the loop current into a voltage, the meters' effective series impedance
varies in a manner that maintains the loop voltage drop constant over the full
4-to-20mA current range. Listed impedance specification applies at 20mA.
1. Set R7 (full scale span/gain adjust) and R3 (zero/offset adjust) fully
clockwise, roughly 22 turns, and place SW1-SW6 to OFF.
2. Select DIP switch setting #2.
Current Loop Input
Min.
Typ.
Max.
Units
Full Scale Input Range
+3.8
+20.4
mA
Input Impedance
80
100
Voltage Drop
1.8
2.0
Volts
Overcurrent Protection
40
mA
Performance
Sampling Rate
2.5 readings per second
Accuracy (1 minute warmup)
0.05%FS 1 Count
Temperature Drift (0 to +60C)
0.15
0.3
Cnts/C
Display
Display Type and Size
3 digit LCD, 0.37"/9.4mm
Polarity Indication
"" for negative readings
Overrange Indication
"1_ _ _ " for negative inputs
"1_ _ _ " for positive inputs
Physical/Environmental
Operating Temperature
0
+60
C
Storage Temperature
20
+75
C
Humidity (Noncondensing)
0
95
%
Case Material
Polycarbonate
Weight
0.6 ounces (17 grams)
Display Reading
SW1
SW2
SW3
4mA
20mA
1. 000 to 1050-1999
Off
Off
Off
2. 000 to 650-1350
On
Off
Off
3. 000 to 450-800
Off
On
Off
4. 000 to 300-500
Off
Off
On
5. 000 to 200-300
On
On
On
Table 1. DMS-20LCD-4/20S (Unipolar Model)
DIP-Switch Settings
DMS-20LCD-4/20S
Unipolar reading, loop-powered LCD meter
DMS-20LCD-4/20B
Bipolar reading, loop-powered LCD meter
DMS-20LCD-4/20P
Positive reading, loop-powered LCD meter
DMS-BZL3
Bezel assembly
DMS-BZL4
Bezel assembly with sealing gasket
DMS-20-CP
Panel cutout punch
Ordering Information
A panel-mount retaining clip is supplied with each model.
1. Desired display readings are:
4mA ="0.00"
20mA = "6.00"
Use DIP-switch setting #3 in Table 1 and enable decimal point DP2
via SW5. Apply 4mA and adjust R3 so the display reads "0.00". Apply
20mA and adjust R7 so the display reads "6.00".
2. Desired display readings are:
4mA = "000"
20mA = "800"
Use DIP-switch setting #2 in Table 1. Apply 4mA and adjust R3 so the
display reads "000". Apply 20mA and adjust R7 so the display reads
"800". For these display readings, no decimal points are used. Set
SW4, SW5 and SW6 to OFF.
3. Desired display readings are:
4mA = ".000"
12mA = ".250"
This example is not as straightforward as the previous two. Notice
that 12mA is exactly halfway between 4mA and 20mA. If we assume
that the input could go up to 20mA, the display reading would then
be: 2 x .250 or ".500". From Table 1 we can now select DIP-switch
setting #4 and enable DP1 via SW4. Apply 4mA and adjust R3 so the
display reads ".000". Apply 12mA and adjust R7 so the display
reads ".250".
Examples (DMS-20LCD-4/20S-Unipolar Model)
ON
1
2
3
4
5
6
ON
DMS-20LCD-4/20S (Unipolar Reading Model)
As shipped, the DMS-20LCD-4/20S is factory calibrated to read "000" for a
4mA input and "1000" for a 20mA input. The following worst-case procedure
assumes the DMS-20LCD-4/20S is completely mis-adjusted, i.e., both
potentiometers and the DIP switches are randomly set. When performing DIP-
switch settings, be sure the DIP switch's small actuators are firmly engaged in
their fully-ON or fully-OFF positions.
1
2
3
4
5
6
ON
1
2
3
4
5
6
ON
Order on-line at www.datel.com
When looking up DIP-switch settings in the Tables and the desired
display readings can be achieved with either of two different settings,
using the higher setting # will produce less sensitive offset (R3) and span
(R7) adjustments. Please keep in mind that the DMS-20LCD standard
meter (from which the DMS-20LCD-4/20 is derived) has an accuracy
specification of 2 counts (max.). Thus, it may not always be possible to
obtain the exact desired display reading.
3. Apply a precision 4mA input, with proper polarity, and adjust R3 until the
meter's display reads "000".
4. Apply a precision 20mA input and adjust R7 until the meter's display
reads "1000". Repeat steps 3 and 4 to make sure the adjustments do not
affect one another.
5. Select the appropriate decimal point by setting SW4, SW5 or SW6 to
ON (DP1, DP2 or DP3 respectively).
NOTE: If a display reading other than "000" to "1000" is desired,
refer to DIPSwitch Settings Table 1 for SW1SW3 settings.
3
DATEL, Inc., Mansfield, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
3 D I G I T , L C D D I S P L A Y , 4 - 2 0 m A L O O P - P O W E R E D M E T E R S
DMS-20LCD-4/20
DMS-20LCD-4/20
DMS20LCD4/20B (Bipolar Reading Model)
The DMS-20LCD-4/20B's zero-offset circuit differs from the unipolar 'S'
model described above in that with the 'B' model, a half-scale 12mA input is
normally set to display "000". Therefore, all of the of the DIP-switch settings
in Table 2 assume a reading of "000" is desired with a 12mA input. Display
readings other than those shown in Table 2 are possible, contact DATEL for
more information.
When configuring the DMS-20LCD-4/20B for the first time, or when selecting
a new range, set both R3 and R7 fully clockwise (roughly 22 turns) to their
minimum offset/minimum-span positions, respectively. Then select the
desired readings from Table 2 and configure DIP-switches SW1, SW2, and
SW3 accordingly.
The procedure below illustrates how to calibrate the DMS-20LCD-4/20B to
its factory-calibrated readings of "1000" with a 4mA input and "1000" with a
20mA input. When performing DIP-switch settings, be sure the DIP-switch's
small actuators are firmly engaged in their fully-ON or fully-OFF positions.
1. Set both R3 and R7 fully clockwise.
2. Select DIP-switch setting #1 from Table 2.
3. Apply a precision 12mA input and adjust R3 until the meter's display
reads "000".
4. Apply a precision 20mA input and adjust R7 until the meter's display
reads "1000".
5. Apply a precision 4mA input and the display should read "1000".
Repeat steps 3 and 4 to make sure the two adjustments did not
affect one another.
Examples
(DMS-20LCD-4/20B-Bipolar Model)
1. Desired display readings are:
4mA = "1.00"
20mA = "1.00"
Use DIP-switch setting #5 in Table 2 and enable decimal point DP2 via
SW5. Apply 12mA and adjust R3 so the display reads "0.00". Apply
20mA and adjust R7 so the display reads "1.00". Apply 4mA and verify
that the display reads "1.00", readjust R3 and R7 if necessary.
2. Desired display readings are:
4mA = "450"
20mA = "450"
Use DIP-switch setting #2 in Table 2. Apply 12mA and adjust R3 so the
display reads "000". Apply 20mA and adjust R7 so the display reads
"450". Apply 4mA and verify that the display reads "450". Repeat
adjustment procedure if necessary. For these display readings, no
decimal points are used. Set SW4, SW5 and SW6 to OFF.
3. Desired display readings are:
4mA = "650"
20mA = "650"
Notice that these readings can be obtained using either DIP-switch
setting #1 or DIP-switch setting #2 in Table 2. In situations like this where
DIP-switch settings overlap, less-sensitive R3/R7 adjustments can be
achieved if the higher DIP-setting # is selected (setting #2 in this example).
Apply 12mA and adjust R3 so the display reads "000". Apply 20mA and adjust
R7 so the display reads "650". Apply 4mA and verify that the display reads "
650". Repeat adjustment procedure if necessary.
1
2
3
4
5
6
ON
1
2
3
4
5
6
ON
Display Reading
SW1
SW2
SW3
4mA
12mA
20mA
1. 600 to 1000
000
600 to 1000
Off
Off
Off
2. 350 to 650
000
350 to 650
On
Off
Off
3. 250 to 400
000
250 to 400
Off
On
Off
4. 150 to 250
000
150 to 250
Off
Off
On
5. 100 to 150
000
100 to 150
On
On
On
Table 2. DMS-20LCD-4/20B (Bipolar Model)
DIP-Switch Settings
1
2
3
4
5
6
ON
DMS-20LCD-4/20P (Positive Reading Model)
The DMS-20LCD-4/20P's Zero-Offset circuit is optimized to produce
positive readings at both 4mA and 20mA input levels. As shown in Table 3's
first three columns, a 4mA input can be typically adjusted (using R3, Zero/
Offset Adjust) to display any positive reading between "000" and "800". The
corresponding 20mA-input reading is then added to the 4mA offset as a
differential whose magnitude is varied by adjusting R7 (Gain/Span Adjust).
The `Differential Range' column in Table 3 lists the nominal differential
display-readings which can be obtained with R7 at, or very close to, its full-
clockwise, minimum span position. The Differential Range column can be
used as a guide when configuring the meter for the majority of user
applications. Higher differential ranges are obtainable; however, the use of
higher differential readings results in correspondingly-lower positive
readings with 4mA inputs, that is, R3's clockwise adjustment-range is
reduced. Example #3 below illustrates this concept. Please contact DATEL if
there is any doubt as to whether or not the DMS-20LCD-4/20P can be
configured for your display readings requirements.
The first step when configuring the DMS-20LCD-4/20P for the first time, or
when selecting a new range, is to set R3 fully counterclockwise and R7 fully
clockwise (roughly 22 turns) to their minimum offset/minimum span
positions, respectively.
The next step is to calculate the required display differential-reading; this is
accomplished by subtracting the desired 4mA display reading from the
desired 20mA display reading, disregarding decimal points. Then, using the
calculated differential display-reading to select the appropriate DIP-switch
setting # from Table 3, configure DIP-switches SW1, SW2, and SW3
accordingly. Make certain that the DIP-switch's small actuators are firmly
engaged in their fully-ON or fully-OFF positions.
The procedure below describes how to calibrate the meter for an applica-
tion which the DMS-20LCD-4/20P easily accommodates: displaying the
output of a 4-20mA transmitter, that is, "04.0" with a 4mA input and "20.0"
with a 20mA input.
4
DATEL, Inc., Mansfield, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
DMS-20LCD-4/20
3 D I G I T , L C D D I S P L A Y , 4 - 2 0 m A L O O P - P O W E R E D M E T E R S
Table 4. Decimal Point Settings
Figure 2. Typical DMS-20LCD-4/20 Connection Diagram
1. Set R3 fully counterclockwise (minimum offset position) and R7 fully
clockwise (minimum differential span position), roughly 22 turns.
2. Subtract 040 from 200 to yield a differential value of 160; use
this value to select DIP-switch setting #5 in Table 3. Enable decimal
point DP3 by placing SW6 to the ON position.
3. Set the transmitter's output to 4.0mA and carefully adjust R3 clockwise
until the meter's display reads "000".
4. Set the transmitter's output to 20.0mA and adjust R7 counterclock-
wise until the meter's display reads "16.0".
5. Set the transmitter back to 4.0mA and slowly adjust R3 clockwise until
the display reads "04.0". Reapply 20.0mA and the display should now
read "20.0". Repeat steps 3, 4 and 5 to make sure the adjustments did
not affect one another.
Examples (DMS-20LCD-4/20P-Positive Model)
1. Desired display readings are:
4mA = "650"
20mA = "950"
Use DIP-switch setting #4 in Table 3 since subtracting 650 from 950 yields a
differential value of 300. Apply 4mA and adjust R3 until the display reads "000".
Apply 20mA and adjust R7 until the display reads "300" (the differential value
previously calculated). Apply 4mA and adjust R3 until the display reads "650".
Apply 20mA and verify that the display reads "950".
2. Desired display readings are:
4mA = "4.00"
20mA = "19.99"
This example illustrates the DMS-20LCD-4/20P's capability to display higher
differential readings than those indicated in Table 3. This example also
illustrates how the DMS-20LCD-4/20P can be used to display the output
levels of a 4-20mA loop transmitter with higher precision (0.01mA versus
0.1mA) than described above.
Subtracting 400 from 1999 yields a differential of 1599, a value not listed in
Table 3. However, use DIP-switch setting #1 in Table 3 since this setting has
the highest overall offset/span adjustment capabilities. Enable DP2 via SW5
then apply 4mA and adjust R3 so the display reads "0.00". Apply 20mA and
adjust R7 so the display reads "15.99". Apply 4mA and adjust R3 until the
display reads "4.00". Apply 20mA and check to see that the display reads
"19.99" or just overranges ("1--"). Repeat adjustment procedure if necessary.
ON
1
2
3
4
5
6
ON
ON
1
2
3
4
5
6
ON
Table 3. DMS-20LCD-4/20P (Positive Reading Model)
DIP-Switch Settings
Differential Range
4mA Input
20mA Input
Display Reading
SW1
SW2
SW3
Shown for illustrative purposes only, may not be present in all applications
SW4
SW5
SW6
DP1
DP2
DP3
1. 800-1400
900
1700
Off
Off
Off
2. 500-800
850
1350
On
Off
Off
3. 350-500
800
1150
Off
On
Off
4. 250-350
750
1000
Off
Off
On
5. 150-250
750
900
On
On
On
A/D
PROGRAMMABLE LOGIC CONTROLLER
TRANSMITTER &
SIGNAL CONDITIONER
TRANSDUCER
INPUT
+
DMS-20LCD-4/20
+
Vsig
+
GAIN
ZERO
+24V
4-20mA
4-20mA
+
+24Vdc
SUPPLY
+
(TB1-1)
R7
R3
(TB1-2)
5
DATEL, Inc., Mansfield, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
3 D I G I T , L C D D I S P L A Y , 4 - 2 0 m A L O O P - P O W E R E D M E T E R S
DMS-20LCD-4/20
Mechanical Specifications
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES:
2 PL DEC 0.02 (0.51)
3 PL DEC 0.010 (0.254)
WIRE SIZE:
18 to 26 AWG
(Solid or stranded)
STRIPPING LENGTH:
0.20" (5.08mm)
#2-56 INSERT
0.156 (3.96) DEEP
FRONT VIEW
1.280
(32.51)
0.187
(4.75)
OPTIONAL BEZEL (DMS-BZL3 and DMS-BZL4)
RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIONS
1.826 (46.38)
0.838
(21.29)
1.336 (33.93)
1.626 (41.30)
1.07
(27.18)
INTERNAL CORNER RADII:
0.032 (0.81) MAX.
0.145
(3.68)
0.093 (2.362) DIAMETER (4 REQUIRED)
ONLY WHEN USING OPTIONAL BEZEL ASSEMBLY
0.116
(2.95)
BEZEL INSTALLATION
BEZEL
PANEL
RETAINING CLIP INSTALLATION
PANEL
Back View
Front View
DIP
Switches
Gain/Span
Adjust
Zero/Offset
Adjust
Loop
Input
DP2
(SW5)
DP3
(SW6)
DP1
(SW4)
0.80
(20.3)
0.040
(1.02)
1.30
(33.0)
1.38
(35.1)
0.88
(22.4)
0.90
(22.9)
MA
DE
IN U
SA
DM
S-20LCD
-4/
20
R3
R7
12
1
1
1
2
2
34
5
6
34
5
6
ON
ON
+
1
2
3
4
5
6
ON
1
2
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
Internet: www.datel.com Email: sales@datel.com
DATEL (UK) LTD. Tadley, England Tel: (01256)-880444
DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: 01-34-60-01-01
DATEL GmbH Mnchen, Germany Tel: 89-544334-0
DATEL KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-6354-2025
DATEL makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions
contained herein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without notice. The DATEL logo is a registered DATEL,
Inc. trademark.
DS-0400B
07/00
ISO 9001
R E G I S T E R E D
DMS-20LCD-4/20
3 D I G I T , L C D D I S P L A Y , 4 - 2 0 m A L O O P - P O W E R E D M E T E R S
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