DMS-30DR Delta Electronics, DMS-30DR Datasheet - Page 4

• Manufacturer Part Number: DMS-30DR
• Description: Digit Panel Meters
• Manufacturer: Delta Electronics

2. Differential Input Configurations: Differential measurements can be
3. Engineering Scaling: For measuring voltages greater than the full
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APPLICATIONS
DMS-30DR Series
scale input range of a given meter, the input signal must be attenuated.
A simple voltage divider (similar to that shown in Figure 4) will scale
the input to within the range of the selected meter. R1 and R2 should
be precision, ±1%, metal-film resistors with absolute TCR's less than
50ppm/°C. See Ap Note 4 for more information on engineering scaling.
made with all DMS-30DR meters. Figure 3, though not a practical real-
world application, uses a voltage divider to demonstrate the concept
of a differential input signal. Be careful not to exceed the ±2V common
mode voltage limitation for 5V-powered meters.
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Figure 3. Differential Input Configuration
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50kΩ < R1 + R2 < 10MΩ
R1 + R2
Figure 4. Input Attenuation Circuit
R2
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5. Process Control (4-to-20mA) Measurements: In many common pro-
4. Floating Signal Source Measurements: Floating signals can be
Where:
cess-control applications, a 4-to-20mA current loop is used to transmit
information. Because DMS-30DR meters have such high input imped-
ance, a simple shunt resistor across the meter's input can be used to
convert the loop current to a voltage. See Figure 7. The value of the
shunt resistor is a function of the scaling requirements of the particular
application and can be calculated using the following equation:
measured using the circuits shown in Figures 5 and 6. Connecting pin
10 (ANALOG COMMON) or pin 3 (5V RETURN) to (–) INPUT LO (pin
12) provides the reference point for the meter's input.
A "floating" input is a signal that has no galvanic connection to the
meter's power supply. In the figures below, the 1.5V battery illustrates a
true floating input.
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Figure 6. Floating Input Measurements
Figure 5. Floating Input Measurements
= R1 = V
= Full scale reading (in Volts)
= Relative full scale current (in Amps)
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(Alternate Configuration)
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D I G I T A L P A N E L M E T E R S
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