DMS-40LCD-4/20S Series
Ultra-Low 2.9V Loop-Drop 4½ Digit
LCD Display Process Monitor
Technical enquiries
email: [email protected], tel:
+1 508 339 3000
www.murata-ps.com
MPM_DMS401LCD-420S.D01
Page 2 of 5
TECHNICAL NOTES
DECIMAL POINT SETTINGS
Performance/Functional Specifications
Typical at T
A
= +25°C, unless otherwise noted.
(
1) Full Scale Input:
The Display readings shown in Table 1 can typically
be obtained with transmitters having a low-level output of 3.8 to 4.3mA
and a full-scale output of 19.4 to 20.4mA. When using a transmitter
whose output falls outside these ranges and the desired display read-
ings are close to the upper or lower adjustment limits of the selected
DIP-switch setting #, try using the next highest DIP-switch setting #
if, after adjusting R7, the display reading is still too low, or the next
lowest setting # if the display reading is still too high (see example
number 2). Please keep in mind that the DMS-40LCD meter from
which the DMS-40LCD-4/20S is derived has an accuracy specification
of ±3 counts (max.); thus, it may not always be possible to obtain the
exact desired display readings. A change of ±1 count is defined as the
right-hand most digit going up or down by one.
DMS-40LCD-4/20S
4½ digit, LCD, loop-powered meter
DMS-BZL1
Panel-mount bezel assembly
DMS-BZL2
Panel-mount bezel assembly with
sealing gasket
DMS-30-CP
Panel cutout punch
A panel-mount retaining clip is supplied with each meter.
Display readings other than those shown in Table 1 are obtainable.
For example, some negative readings with a 4mA input are possible.
Consult DATEL for more information regarding display readings not
shown in the table.
(2) Max. Loop-Voltage Drop/Max. Loop impedance
: The maximum loop
voltage-drop and maximum loop impedance (burden) are both speci-
fied with the meter configured for DIP-Switch setting #20 and an input
loop current of 20.0mA.
(3) Temperature Drift:
Temperature drift of zero and temperature drift of
gain are both specified with the meter configured for range #20 with a
4mA input adjusted (using R3) to read “0000” ±1 count, and a 20mA
input adjusted (using R7) to read “19000” ±2 counts at an initial ambi-
ent temperature of 25°C.
The temperature drift of gain is proportional to the selected full-scale
range. It is typically less pronounced at the lower range settings, that
is, if the observed gain drift of a particular meter is +12 counts when
reading “19000” on range #20 at 40°C, the same meter will most
likely have a drift of only +6 counts when reading “9000” on range
#12 at 40°C.
The normally very accurate, temperature-insensitive autozero feature
of the DMS-40LCD-4/20S’s built-in analog-to-digital converter (A/D)
is not a significant factor in determining the meter’s overall zero-
reading stability over its rated operating temperature because an
offset voltage is applied to the A/D’s LO input. This offset is used to
null the signal voltage developed with a 4mA input. In order for the
A/D to display a steady “0000” ±1 digit, the autozero circuitry requires
both A/D inputs to always be at exactly zero volts.
The meter’s zero-reading stability over its specified operating
temperature is affected by the drift of three terms: the voltage
developed by the meter’s offset circuitry; the voltage developed
across the meter’s input resistors with a 4mA input; and the stability of
the applied 4mA input signal itself. In the lower DIP-switch settings
(ranges #1-4), the meter’s parasitic etch and switch impedances also
contribute a small error voltage.
The meter’s performance with regards to span stability over
temperature is affected by the drift of the meter’s gain circuitry and
loop input-resistors. To minimize these drifts in applications requiring
the utmost in temperature stability, where possible, the meter should
be calibrated at its anticipated operating temperature.
Since the DMS-40LCD-4/20S uses extremely-stable thin-film chip
resistors, periodic re-calibration is typically required only in
environmentally demanding applications where shock, vibration,
and/or temperature extremes may have a detrimental effect on the
20-turn potentiometers.
Using the chart below as a guide, the DMS-40LCD-4/20S’s decimal
points can be configured to suit the user’s particular readout
requirements. To enable a desired decimal point place its DIP switch
to the ON position (up). Please note that the decimal points are
merely placeholders, that is, they can all be on or all off; they do not
affect the meter’s operation and/or display readings.
Current Loop Input
Min.
Typ.
Max.
Units
Full Scale Input Range (1)
+3.8
–
+20.4
mA
Loop Burden (2)
–
–
190
Ohms
Voltage Drop (2)
–
2.9
3.8
Volts
Overcurrent Protection
–
–
±40
mA
Performance
Sampling Rate
2.5 reading per second
Accuracy (1 minute warm-up)
±0.05%FS ±1 Count
Temperature Drift of Span (3)
–
±0.3
±0.6
Cnts/°C
Temperature Drift of Zero (3)
–
±0.2
±0.5
Cnts/°C
Display
Display Type and Size
4½ digit, 0.4"/10.2mm high LCD
Polarity Indication
"–" for negative readings
Overrange Indication
"–1_ _ _" for negative inputs
"1_ _ _" for positive inputs
Physical/Environmental
Operating Temperature
0
–
+50
°C
Storage Temperature
–20
–
+75
°C
Humidity (non-condensing)
0
–
95
°C
Case Material
Polycarbonate
Weight
0.1 ounces (28 grams)
Ordering Information