DMS-EB データシートの表示（PDF） - DATEL Data Acquisition products
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DMS-EB
DATEL Data Acquisition products
DMS-EB Datasheet PDF : 6 Pages
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3½ D I G I T, L E D D I S P L AY D I G I TA L PA N E L VO LT M E T E R S
DMS-30PC
Applications
Example: For a meter with a 2V full scale input (1.999 full
scale reading) and a desired display reading of
"1000" (with an input of 20mA), VFsr = 1.000 Volts
RShunt = 1.000V/(0.020 – 0.004)A
RShunt = 1.000V/0.016A = 62.5 Ohms
To calibrate the circuit of Figure 7, perform the following:
1. With 4mA applied, adjust the 50kΩ potentiometer (R2) to
display a reading of "000" (assuming that is the desired
reading).
2. With 20mA applied, adjust the gain-adjust potentiometer on
the back of the meter to display a reading of "1000". For
different full scale readings, alter the value of RShunt accordingly.
4-20mA R1
11
(+) IN HI
10
ANA COMM
12
(–) IN LO
R2
–
50k
120 VAC
DATEL
UPA-5/500
AC to DC Converter
DMS-30PC-1
8
REF OUT
9
1.23V
REF
1
5V SUP
3
5V RET
7
REF IN
Figure 7. 4-to-20mA Current Loop Operation
6. Power Supply Monitoring: One of the most common digital
panel meter applications involves monitoring the output voltage of
the system power supply — often this supply also powers the
meter itself. The low-power, red LED DMS-30PC-2-RL can be
configured to allow power supply monitoring over the range of
4.5-18Vdc. The circuit in Figure 8 uses a low-drop-out, three-
terminal regulator (LM-2931Z-5, available from National
Semiconductor) to provide regulated 5V power to the meter. The
LM-2931 was chosen because it has the following on-chip
LM2931Z-5
+
4.5 - 18Vdc
–
IN OUT
GND
+
22µF
10V
(+) IN HI
11
1
+5V SUP
3
5V RET
DMS-30PC-2-RL
5
DP2
7
REF
IN
8
REF
OUT
12
(–) IN LO
Figure 8. 4.5-18V Power Supply Monitor
protection features: reverse polarity, short circuit and thermal run-
away. When using other, higher-power, DMS-30PC models with
three-terminal regulators, be sure to consult the regulator
manufacturer's data sheet to ensure the regulator is being
utilized safely and correctly.
7. Digital Ammeter: Digital ammeters are finding ever-increasing
usage because analog-style ammeters (moving-vane types) now
cost roughly the same as their digital counterparts. Additionally,
analog ammeters are not nearly as rugged as modern digital
panel voltmeters. Figure 9 illustrates a typical ammeter
application. The circuit uses a ±200mV input meter
— the preferred range for most ammeters — to measure the
voltage developed across a 0.1Ω current shunt. The circuit
shown represents a basic ammeter connection diagram. A
detailed application note describing digital dc ammeters is
included in DATEL's new Digital Panel Meter Databook.
1
+5V SUP
+
5Vdc
3
–
5V RET
DMS-30PC-0-YS
6
DP1
12
(–) IN LO
11
(+) IN HI
1.5 Amp (Load Current)
0.150V
0.1Ω
RShunt
Load
(3.3 Ω)
8
REF OUT
7
REF IN
Figure 9. Basic DC Ammeter Circuit
8. External Gain Adjustment: Connect REFERENCE OUT
(pin 8) to REFERENCE IN (pin 7) for normal, factory calibrated,
operation. Use the +1.23V REFERENCE OUT (pin 9) for
applications needing external gain adjustment. Figure 10 shows
the wiring configuration for each model. Calibration is performed
with a precise, near-full-scale, input voltage.
OUT
VOLTAGE
12 CALIBRATOR
COM
11
(+) IN HI
DMS-30PC
3
5V RET
12
(–) IN LO
10
8
ANA COMM
NC
7
REF IN
9
1.23V REF
8.45k, 1%
1k
10 to 20 Turns
1k
8.45k, 1%
10 to 20 Turns
Connections
for ±2V, ±20V
and ±200V models
Connections
for ±200mV
models
Figure 10. External Gain Adjustment
5
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