DMR35-DCA.A01.D04 Page 3 of 8

DMR35-DCA Series

Precision DC Shunt Ammeter

www.murata-ps.com

OPERATION:

Measurement Type and Capabilities

The DMR35 series of digital ammeters employ a precision ADC and a low-power microcontroller to measure DC current. These meters provide full-scale

measurement ranges spanning 1 ampere to 25 amperes with extremely low burden voltages. These meters measurement systems supports a common-

mode input voltage range of up to +/-48V with respect to the power supply return (-VS connection), simplifying high-side, low-side, and negative rail

current measurements.

FRONT PANEL & FRONT PANEL LAYOUT AND FUNCTION

Bar-graph Display: The 21 segment bar-graph display responds quickly and smoothly like an

analog meter movement to aid in reading rapidly changing measurements.

Numeric Display: The 3-1/2 digit display provides precise measurements for steady-state and

slowly changing measurement values.

REAR PANEL LAYOUT AND SCREW TERMINAL CONNECTIONS

Four screw terminals are provided for power and measurement connections, as well as a 5-position DIP switch for meter configuration, as described

below.

Rear Layout

Terminal #

Name

Function

DM35-DCA1

1

+VS

Power supply input terminals (9-32 VDC)

2

-VS

3

+I_IN

Current measurement input terminals

4

-I_IN

DIP Switch: Five individual switches support display intensity settings (SW1-SW2) and

measurement range selection (SW3-SW5)

Note: It is important to tighten all screw-terminals to their torque specifications. Proper

tightening will help ensure reliable operation. Applications subject to vibration should use

stranded wire.

DMR35-DCA2

(large terminal block for 25A)

POWER SUPPLY CONNECTIONS

The meter is powered through the +VS and –VS terminals and requires a DC power supply which may range from 9VDC to 32VDC. This supply is

electrically isolated from the meter’s measurement electronics, so that the meter’s measurement input terminals (+I_IN, -I_IN) do not need to be

connected to the meter’s power return terminal (-VS), and may vary as much as +/-48V from this connection. Please note that the meter’s isolation

barrier is intended only to simplify measurements, and not for safety purposes – the maximum voltage between the power supply terminals (+VS or –

VS) and the measurement input terminals (+I_IN, -I_IN) must be limited to +/-48VDC. The DMR35 series of meters incorporates protection against

momentary applications of both overvoltage and reverse polarity to the power supply(+VS, -VS) terminals. Depending on regulatory and application

requirements it may also be necessary for the user to add external fusing.

MEASUREMENT INPUTS

Current to be measured by the DMR35 is passed through the +I_IN and –I_IN terminals. This requires that the meter be inserted in the line in which

the current is to be measured. Unlike many panel meters, the DMR35 series’ measurement inputs are electrically isolated from the power supply

terminals, which allows for fully differential measurements over a common-mode range of +/-48V with respect to the power supply terminals +VS or -

VS.