2
DATEL, Inc., Mansfield, MA 02048 (USA)
•
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
•
E–mail: [email protected]
•
Internet: www.datel.com
Operating and Setup Instructions
Performance/Functional Specifications
Typical at T
A
= +25°C, unless otherwise noted.
DMS-20LCD-4/20
3 ½ 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
➀
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.
➁
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.
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-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.
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 (DP3, DP2 or DP1 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
+3.8
––
+20.4
mA
Input Impedance
➁
––
80
100
Ω
Voltage Drop
➁
––
1.8
2.0
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 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
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 SW6. 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
1
2
3
4
5
6
ON
1
2
3
4
5
6
ON
Order on-line at www.datel.com
DIP-switch settings, be sure the DIP switch's small actuators are firmly
engaged in their fully-ON or fully-OFF positions.