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.
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 email@example.com
Is the calibration of Dataforth modules traceable to NIST standards?
Yes, calibration of Dataforth modules is traceable to NIST standards.
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
Where can I find the MTBF of my module?
Information on MTBF for SCM5B, SCM7B, 8B and DSCA is available on our website. Please see application note AN802 for more details. Application notes can be found under the "Literature" tab on the top navigation bar.
What does "Response time, 90% span" mean on the datasheet for my module?
Normally, a response time figure refers to how quickly a module's output can "respond" to a change in the input signal. "Response time, 90% span" refers to how fast a module can adjust its output when a step signal is applied at the input, where the magnitude of this step input is 90% of the input span of the module.
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
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.
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.
What does it mean when an input module has for example a 3kHz bandwidth?
A 3kHz bandwidth on an input module means it can accept voltages from DC to 3000Hz. Any frequency higher than that and the signal will start to be attenuated by the filter at the input.
What size wires do the DSCA modules accept?
DSCA module screw terminals are rated to wire gage AWG: 28 – 12.
Do DSCA modules come with screw terminal blocks installed?
Yes, DSCA modules do come with the screw terminal blocks installed. The screw terminal accessories listed in our catalog are intended as replacements in case a terminal block is damaged or lost.
Due to resource constraints on my computer, I'm unable to open the three dimensional CAD models provided on your website. Does Dataforth provide two demensional CAD models for download as well?
Two dimensional CAD models can be generated upon customer request. Please contact Customer Service for assistance.
Can Dataforth analog modules be used in high vibration environments? If so, what type of testing or certification was completed?
SCM5B, SCM7B, 8B SensorLex, and DSCA modules are well suited for use in high vibration environments. These modules and their associated accessories have undergone testing for random vibration, shock, and swept sine wave vibration. Details of each of these testing methods are provided below:
Random Vibration (Operating):
○ MIL-STD 202G, Method 214A, Condition 1
- Frequency Range: 50-2000Hz, flat spectrum
- Vibration Intensity: 7.56 Grms
- Duration: 10min/axis (X, Y, Z)
○ MIL-STD-810F, Method 516.5
- Pulse Shape: Sawtooth
- Test Level: 30G
- Duration 11ms
- Orientation: +/-X, +/-Y, +/-Z
Swept Sine Vibration (Operating)
○ MIL-STD-810G, Method 514.6, modified
- Frequency Range: 10-2000Hz
- Vibration Intensity: 5Gp-p
- Sweep Rate: 1 octave/min
- Orientation: X, Y, Z
Declaration of conformity for the above-listed tests can be provided upon customer request. Please contact customer service if a copy of the declaration is needed.
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