Each DSCA42 2-wire transmitter interface module provides a single channel of 4 to 20mA process current input which is filtered, isolated, amplified, and converted to a high-level voltage output. An isolated 24V 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 powerline voltages up to 240VAC 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.
  • Accepts Process Loop Signals
  • Industry Standard Output of either 0-10V, 2-10V, 0-20mA, or 4-20mA
  • Provides Isolated Loop Excitation
  • 1500Vrms Transformer Isolation
  • ANSI/IEEE C37.90.1 Transient Protection
  • Input Protection to 240VAC Continuous
  • True 3-Way Isolation
  • Wide Range of Supply Voltage
  • 105dB CMR
  • 5 Poles of Filtering
  • ±0.03% Accuracy
  • ±0.01% Linearity
  • Easily Mounts on Standard DIN Rail
  • C-UL-US Listed
  • CE and ATEX Compliant
2-Wire Transmitter Interface Signal Conditioners With Loop Power

DSCA42 Devices


Part Number Input RangeOutput RangeMechanical FormatInternal Power SupplyIsolation VoltageIsolation TypeAccuracySupply Voltage
4 to 20 mA 0 to +10 V DIN rail Powers 2-Wire Transmitter 1500 Vrms Transformer 3-way ±0.03% Span 19 to 29 Vdc (+24V Nom)
4 to 20 mA 4 to 20 mA DIN rail Powers 2-Wire Transmitter 1500 Vrms Transformer 3-way ±0.03% Span 19 to 29 Vdc (+24V Nom)
4 to 20 mA 0 to 20 mA DIN rail Powers 2-Wire Transmitter 1500 Vrms Transformer 3-way ±0.03% Span 19 to 29 Vdc (+24V Nom)
4 to 20 mA +2 to +10 V DIN rail Powers 2-Wire Transmitter 1500 Vrms Transformer 3-way ±0.03% Span 19 to 29 Vdc (+24V Nom)

Frequently Asked Questions


Can Dataforth provide calibration reports for modules I purchased?
Yes we can provide calibration reports for the modules that you purchased.

You can either
a) visit https://www.dataforth.com/TestDataReport.aspx to search for Test Report Datasheets by Serial Number or
b) you can send us a list of model numbers and their serial numbers to support@dataforth.com

Is an external conversion resistor required in order to use the DSCA42 module?
No, an external conversion resistor is not required in order to use the DSCA42 module. The current/voltage conversion is achieved by an internal resistor as shown in the block diagram in the data sheet.

Keywords/Phrases: DSCA42, internal resistor, external conversion resistor

Does Dataforth have any DSCA modules that can operate on a 12Vdc power supply?
Dataforth does not have any custom modules that run on 12VDC power. Most DSCA modules require a minimum power supply voltage of 15VDC while some require a minimum of 19VDC. Both are suitable for use with nominal 24VDC power supplies over the full operating temperature range of -40C to +85C. Dataforth offers a line of accessory power supplies, PWR-PS5RxW, which have been qualified for use with the DSCA product line. https://www.dataforth.com/catalog/pdf/PWR-PS5RxW.pdf

Why do I see a -10V shift when I change to a DSCL23 from a DSCA42-01C or similar?
The DSCA42-01C internal electronics is powered by an overall power supply and then the module output circuitry provides the output current whose return side (or negative side) is connected internally to the power supply common. This causes the output signal to be positive with respect to the common.

Whereas, the DSCL23 is loop-powered through its output terminals. That puts the 4-20mA receiver (the load) in series with the power supply. So when you measure the voltage from the power supply common (- terminal) to the other side of the load you will see a negative signal. The module could be made usable if the power supply has a fully floating output and you can make terminal 1 (the return current terminal) the common and measure the positive signal across the load from the power supply (-) to terminal 1 (the return current terminal), the common.

A better match for your application is the DSCA42-01C. Its internal electronics is powered by an overall power supply and then the module output circuitry provides the output current whose return side (or negative side) can be connected to the power supply common. This causes the output signal to be positive with respect to the common.

Keywords/Phrases: 4-20mA isolator with loop power, 2-wire transmitter interface signal conditioner with loop power

How do I convert an RMS voltage to its corresponding peak voltage?
To convert an RMS voltage to its corresponding peak voltage, you simply take the RMS voltage value and multiply it by the square root of 2, or roughly 1.414.

For example, 1500Vrms corresponds to a peak voltage of 1500 * 1.414 = 2121 Vp

What is the output resolution of the DSCA series?
The DSCA series is completely analog, so the output resolution cannot be expressed in terms of bits as it is not a digital signal. The only thing that would cause any uncertainty/lack of clarity in your output signal would be the output ripple and noise, which is rated at a typical value of 0.025% span RMS as listed in the datasheet.

If the input range of my signal conditioner is -1V to +1V and the output range is 0 to 10V, does this mean that it ignores polarity?
A signal conditioner with these I/O ranges does not mean that the module ignores the polarity of your voltage input. The output of voltage input modules are scaled linearly, meaning an input of -1V would correspond to an output of 0V, an input of 0V would correspond to an output of 5V, an input of +1V would correspond to an output of 10V, and so on.

How does the load resistance of a module affect the noise at the output?
Noise at the output of a module is independent of load resistance.

Is the calibration of Dataforth modules traceable to NIST standards?
Yes, calibration of Dataforth modules is traceable to NIST standards.
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