DATEL DMS-20PC-4-20S, DMS-20PC-4-20P, DMS-20PC-4-20B Datasheet

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

Actual Size

DMS-20PC-4/20 Series

The DMS-20PC-4/20 Series are the world's fi rst loop-powered digital panel meters
with a large, easy-to-read, bright red, LED display. All operating power is derived
directly from the loop current itself—no external power supply is required! The large,

0.37"/9.4mm digits exhibit uniform intensity over the entire 4-20mA operating range.
Additionally, the total maximum loop voltage drop is only 5V! Users no longer have to
settle for diffi cult-to-read LCD displays in loop-powered applications.

Both gain (span) and offset (zero) adjustments are performed with on-board, preci­sion, 20-turn potentiometers. All decimal-point and range-change selections are
made on a six-position DIP switch featuring vibration-resistant, gold-plated contacts.
Unlike competitive meters, there are no jumpers or solder gaps to open or close.
Connections to the current loop are made via a reliable, two-position, screw-type
terminal block.

The DMS-20PC-4/20's DIP switch and adjustment potentiometers accommodate
hundreds of different input-current/output-reading combinations. This versatility practi­cally eliminates the need to order more costly, long-lead-time, factory-customized "spe­cials" in applications in which several different-range meters are required. An optional
bezel assembly, featuring screw fasteners and a rubber seal, simplifi es panel mounting
and provides excellent resistance to environmental dust and moisture. All these out­standing features combine to make the DMS-20PC-4/20 Series the perfect meters for
prototype and OEM 4-20mA current-loop instrumentation.

Subminiature

4-20mA Loop-Powered

3½ Digit, LED ProcessMonitors

Figure 1. DMS-20PC-4/ 20 Series Simplifi ed Schematic

Features

• Industry's fi rst loop-powered meter

with a large, easy-to-read, LED display!

• Self-powered, no external

supply required

• Unipolar, Bipolar and Positive Reading

Models

• Large, 0.37"/9.4mm digits

• Excellent display intensity

• Constant 5V max. total loop drop

• High-quality, 20-turn, span (gain) and

zero (offset) adjustments

• DIP-switch selectable range and

decimal points

• Hundreds of input/readout combinations

• Vibration-resistant package; Reliable

screw-terminal input connections

New! Bipolar and Positive Reading Models

®®

Order online at www.datel.com

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

DP3DP2DP1

R3 R7

+–

TB1

LOOP INPUT

1

2

3

45

6

ON

–+

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

DMS-20PC-4/20

2

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

Operating and Setup Instructions

Performance/Functional Specifi cations

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

➀ The DMS-20PC-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.

➁ Because DATEL's DMS-4/20 loop-powered meters employ active circuitry to con-

vert 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 specifi cation applies at 20mA.

➂ 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-20PC standard meter (from which the DMS-20PC-4/20 is derived)
has an accuracy specifi cation of ±2 counts (max.). Thus, it may not always be
possible to obtain the exact desired display reading.

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.

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.

Current Loop Input Min. Typ. Max. Units

Full Scale Input Range ➀ +4 –– +20 mA
Input Impedance ➁ –– 250 –– Ω
Voltage Drop ➁ –– 4.5 5.0 Volts
Overcurrent Protection ➀ –– –– ±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, red LED, 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 –40 –– +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-20PC-4/20S (Unipolar Model) DIP-Switch Settings

DMS-20PC-4/20S Unipolar reading, loop-powered LED meter
DMS-20PC-4/20B Bipolar reading, loop-powered LED meter
DMS-20PC-4/20P Positive reading, loop-powered LED meter
DMS-BZL3 Bezel assembly
DMS-BZL4 Bezel assembly with sealing gasket
DMS-20-CP Panel cutout punch

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-20PC-4/20S-Unipolar Model)

DMS-20PC-4/20S (Unipolar Reading Model)

As shipped, the DMS-20PC-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-20PC-4/20S is completely mis-adjusted, i.e.,

both potentiometers and the DIP switches are randomly set. When perform-

ing DIP-switch settings, be sure the DIP switch's small actuators are fi rmly

engaged in their fully-ON or fully-OFF positions.

1

2

3

4

56

ON

123

4

5

6

ON

1234

56

ON

Ordering Information