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2-Wire Transmitter Interface Signal Conditioners with Loop Power

Each DSCA42 2-wire transmitter interface module provides a single channel of 4 to 20 mA process current input which is filtered, isolated, amplified, and converted to a high-level voltage output. An isolated 24 V power supply is provided to power the 2-wire transmitter. Signal filtering is accomplished with a five-pole filter which is optimized for step response. An anti-aliasing pole is located on the field side of the isolation barrier, and the other four poles are on the system side. After the initial field-side filtering, the input signal is chopped by a proprietary chopper circuit. Isolation is provided by transformer coupling, again using a proprietary technique to suppress transmission of common mode spikes or surges.

Module output is either voltage or current. For current output models a dedicated loop supply is provided at terminal 3 (+OUT) with loop return located at terminal 4 (-OUT). The system-side load may be either floating or grounded.

Special input circuits provide protection against accidental connection of power-line voltages up to 240 VAC and against transient events as defined by ANSI/IEEE C37.90.1. Protection circuits are also present on the signal output and power input terminals to guard against transient events and power reversal. Signal and power lines are secured to the module using screw terminals which are in pluggable terminal blocks for ease of system assembly and reconfiguration.

The modules have excellent stability over time and do not require recalibration, however, zero and span settings are adjustable up to ± 5% to accommodate situations where fine-tuning is desired. The adjustments are made using potentiometers located under the front panel label and are non-interactive for ease of use.

Circuit diagram Dataforth DSCA42

Block Diagram DSCA42

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2 Modules for Type DSCA42:

DSCA42-02 4 mA to 20 mA DSCA42 Isolated 2-Wire Transmitter Interface Signal Conditioner with Loop Power and Current-Input
DSCA42-01 4 mA to 20 mA DSCA42 Isolated 2-Wire Transmitter Interface Signal Conditioner with Loop Power and Current-Input


  • Input: mA-Signal
  • Output: 0 V … 10 V / 2 V … 10 V / 0 mA … 20 mA / 4 mA … 20 mA
  • Bandwidth 100 Hz
  • Isolation 1500 Vrms
  • Input protection 240 Vrms
  • Input Resistance < 100 Ohm
  • Accuracy ± 0.03%
  • Linearity ± 0.01%
  • ANSI/IEEE C37.90.1 Input protection
  • CMR 105dB
  • True 3-way isolation
  • NMR: 100dB / Decade > 100 Hz
  • Power Supply 19 to 29 VDC
  • Operating Temperature Range -40°C … +80°C
  • Adjustability of +/-5 % Zero and span
  • 5-pol. Filtering
  • Dimensions 75 x 22.5 x 105 mm
  • DIN Rail Mounting
  • CE and ATEX certified, C-UL-US compliant
  • Special Solutions on request