DATEL DMS-BZL4, DMS-BZL3, DMS-20-CP, DMS-20LCD-4-20S, DMS-20LCD-4-20P Datasheet

DATEL, Inc., Mansfield, MA 02048 (USA) • T el: [phone], [phone] Fax: [phone] • E–mail: [e-mail] • 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 compa­rably 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 per­formed 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.

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Super-low loop drop: 1.8V typical, 2.0V max.

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Self-powered, no separate supply required

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Unipolar, Bipolar, and Positive Reading
Models

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Subminiature package—Less than 0.90”
behind-the-panel depth

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Large, 0.37"/9.4mm high, sunlight-viewable
LCD display

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Non-interacting gain (span) and offset
(zero) 20-turn potentiometers

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DIP-switch selectable range and decimal
points

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Hundreds of different input/readout
combinations

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Vibration-resistant package; reliable
screw-terminal input connections

DATA

3 ½ D IG IT A /D
CONVERTER

DC/DC

CONVERTER

BAND-G AP

REFERENCE

CIRCUIT

DIP SW ITCHES

ZER O

ADJUST

GAIN

ADJUST

123

CURRENT TO

VOLTAGE

CONVERTER

+5V 5V

DP3DP2DP1

R3 R7



TB1

LO O P IN P U T

5

61

112

2

2

3456

3

344

5

6

ON

ON

ON

+

4-20mA Input Loop-Powered

Ultra-Low 1.8V Loop Drop , 3½ Digit

LCD-Display Process Monitors

Actual Size

Order on-line
at www.datel.com

2

DATEL, Inc., Mansfield, MA 02048 (USA) • T el: [phone], [phone] Fax: [phone] • E–mail: [e-mail] • Internet: www.datel.com

DMS-20LCD-4/20

3½ DIGIT, LCD DISPLAY, 4-20mA LOOP-POWERED METERS

Operating and Setup Instructions

Performance/Functional Specifications

Typical at TA = +25°C, unless otherwise noted.

À

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.

Á

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

À

+3.8 –– +20.4 mA

Input Impedance

Á

–– 80 100

Ω

Voltage Drop

Á

–– 1.8 2.0 Volts

Overcurrent Protection

À

–– –– ±40 mA

Performance

Sampling Rate 2.5 readings per second
Accuracy (1 minute warm–up) ±0.05%FS ±1 Count
Temperature Drift (0 to +60°C) –– ±0.15 ±0.3 Cnts/°C

Display

Display Type and Size 3½ 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 (Non–condensing) 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

Â

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". F rom 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 DIP­switch 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

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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 DIP–Switch Settings Table 1 for SW1–SW3 settings.