Frequently Asked Questions
Do you have replacement terminal blocks for DSCA and DSCT modules?
Yes. Replacement terminal blocks are the following.
DSCAX-01 labeled 1 2 3 4.
DSCAX-02 labeled 5 6 7 8.
Keywords/Phrases: DSCA terminal blocks, replacement terminal blocks, DSCA replacement terminal blocks, DSCT terminal blocks, DSCT replacement terminal blocks
On a DSCAxx-xxC, -xxE, is an external load resistor required in order to convert the output loop current to a voltage?
An external load resistor is required only if the input does not have an internal current to voltage conversion resistor.
Find out the maximum load resistance the output can drive. The maximum load resistance the DSCAxx-xxC, -xxE output can drive is 600 Ohms.
Find out the voltage range the input can accept. Be sure to include the voltage drop at 20mA for the resistance of the length of the lead wires. To calculate the required load resistance, divide the maximum input voltage required by 20mA. The result is the load resistance your application needs to operate properly.
Example: Rin = Vin / 20mA Rin = 10V / 0.02A = 500 Ohms
Lead wire margin allowance example:
Vwire = Rout max x 20mA – Vin Vwire = 600 Ohms x 0.02A – 10V = 12V – 10V = 2V
Keywords/Phrases: DSCA, DSCA current loop output, external load resistor, impedance, ohms
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
Could you explain, what is the main difference between the DSCA41 and the DSCA49?
The main difference is the DSCA41 is an input module and the DSCA49 is an output module, which means:
A. The DSCA41 module has its input on the isolated field side of the module, connected to it through screw terminals 6 and 7. The DSCA41 module has its output on the system and power supply side of the module, connected to it through screw terminals 3 and 4.
B. The DSCA49 module has its output on the isolated field side of the module, connected to it through screw terminals 6 and 7. The DSCA49 module has its input on the system and power supply side of the module, connected to it through terminals 3 and 4.
Keywords/Phrases: DSCA, DSCA module, DSCA input module, DSCA output module, DSCA41, DSCA49
On DSCA’s, what are the zero and span adjusters physically?
The DSCA and DSCT zero and span adjustments are made using trimpots located under the front panel label and are non-interactive for ease of use. The trimpot screw heads are behind perforated circular knockouts labeled Ø and <->. The screw heads are slotted to accept a narrow flat blade screwdriver. The zero and span adjusters are 25Turn trimpots.
Keywords/Phrases: DSCA zero, DSCA span, DSCT zero, DSCT span, DSCA adjustment, DSCT adjustment, trimpots
Can the DSCA modules be Re-Calibrated in the field?
Dataforth modules are designed to be highly stable, thus they do not require re-calibration.
DSCA modules can be re-calibrated in the field and they can be re-calibrated by Dataforth.
To re-calibrate DSCA modules in the field, download AN801 from the Media Attachments box to the right of the topic main body and follow the instructions.
We do offer a re-calibration service. For details, please contact sales by email at firstname.lastname@example.org or by phone at 1 800 444 7644 press 1 for sales.”
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
Can you explain what is the difference between the “Standard frequency range” and the “Extended frequency range” for the DSCA33 module?
The user does not have to do anything special; the module operates seamlessly over the full frequency range of 45Hz to 20kHz. We needed to split the full frequency range into two ranges so we could define and specify the different accuracy levels associated with each subrange.
If you look further down the DSCA33 Specifications under Accuracy, you will notice the Standard frequency range from 45Hz to 1kHz carries an additional +/-0.25% Reading error. This error is in addition to the +/-0.25% Span error at 50/60Hz. So the total accuracy error will be +/-0.25% Span + (+/-0.25% Reading) = +/-0.50%.
And the Extended frequency range from 1kHz to 20kHz carries an additional +/-0.75% Reading error. This error is in addition to the +/-0.25% Span error at 50/60Hz. So the total accuracy error will be +/-0.25% Span + (+/-0.75% Reading) = +/-1.00%.
Keywords/Phrases: DSCA RMS, DSCA True RMS, DSCA RMS input module, DSCA True RMS input module, DSCA33
For DSCA49 modules when I give LabVIEW (or other DAQ software) an output command, I get no output from terminals 3 & 4, why?
That’s because the DSCA 49 and the DSCA 39 are output modules, are connected the reverse of input modules, they have their inputs on terminals 3 & 4, the system side (power supply side). They provide their outputs on terminals 6 & 7, the isolated field side.
Keywords/Phrases: DSCA, DSCA module, DSCA output module, DSCA 49, DSCA 39
What is the recommended torque for DSCA screw terminals?
0.5Nm to 0.6Nm is the recommended range.
0.6Nm is the max recommended torque, but it is still short of damage to the unit.
KEYWORDS/PHRASES: DSCA, screw terminal, DSCA screw terminal, torque
On a DSCAxx-xxC, -xxE, is an external power supply required in order to provide output loop current?
No, an external loop power supply is not required in order to provide output loop current. The DSCAxx-xxC and –xxE current output modules have what is known as an active current output. They source the loop current out of their output terminals.
Keywords/Phrases: DSCA, DSCA current loop output, external loop power, external loop supply, external loop power supply
How do I troubleshoot a set-up with 100 Ohm Platinum RTD while using it with DSCA34-01 input module?
Measure the RTD with an ohmmeter. If it is near the specified resistance for its type, then it is likely good.
If an RTD is not available, power the module.
Connect 100 Ohms across terminals 5 and 7 and connect a shorting jumper across terminals 5 and 6.
For DSCA34-01, measure about 5V across output terminals 3 and 4.
For DSCA34-01C, measure about 12mA across output terminals 3 and 4.
For DSCA34-01E, measure about 10mA across output terminals 3 and 4.
Keywords/Phrases: DSCA34, DSCA34 troubleshooting, Pt100, platinum, nickel, RTD
Is there an extra charge for the extended frequency range to 20kHz for a DSCA33-01C?
There is no extra charge for the extended frequency range in the DSCA33. If you look in the DSCA33 Specifications under Accuracy, you will notice the extended frequency range carries an additional +/-0.75% of Reading error. This error is in addition to the +/-0.25% Span error at 50/60Hz. So the total accuracy error will be +/-0.25% + (+/-0.75%) = +/-1.00%.
ATEX conformity: Is it possible to use the DSCA38-12C in zone IIC (hydrogen)?
The DSCA38-12C conforms to EN60079-15 2005.
For use in:
Category 3 (Zone 2)
What does “sensitivity” mean on my strain gage input module?
The sensitivity is listed on the datasheet to help determine what strain gages/load cells will be compatible with that module. Strain gages do not have a specific voltage output range (i.e. -30mV to 30mV) but rather a voltage output range that varies depending on the excitation voltage applied to the strain gage (its "sensitivity"). Since our strain gage modules have a fixed voltage input range and a fixed excitation voltage, the sensitivity is the most reliable way to determine if a strain gage is compatible with our module.
For example, a load cell with a 3mV/V sensitivity will output 30mV at full scale with a 10V excitation voltage, because 3mV/V * 10 V = 30mV. A signal conditioner with a 10V excitation and a -30mV to 30mV input range will be compatible with a load cell of 3mV/V sensitivity.
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
Does Dataforth have any options for thermistor input?
Thermistor interface has never been designed for SCM7B, 8B, DSCT, or MAQ20 product lines. However, we do have some custom products in the SCM5B line that can accept thermistor interface. Any SCM5B36, SCM7B36, 8B36, DSCA36, DSCT36 module with potentiometer input 0-10kohm may also be suitable for some sensors.
What is DSCA32 output resistance?
DSCA32 output resistance is: R out <= 1 Ohm
Keywords/Phrases: output resistance, DSCA32 output resistance
For a half-wave rectified sine, Crest Factor = 2, in a DSCA33, which additional error spec do I apply; the one for Crest Factor 1 to 2 or 2 to 3?
The DSCA33 Crest Factor additional error is specified in several ranges of 1 to 2, 2 to 3, 3 to 4, and 4 to 5. For every whole number Crest Factor 2 and greater, choose the pair with the applicable whole number to the right. That whole number is included in the range or mathematically: <=. The whole number at the left of a range is excluded from the range or mathematically: >.
Keywords/Phrases: DSCA33, Crest Factor, DSCA33 and Crest Factor
On the 8B51, can I apply the + and – input leads “backwards” to reverse the polarity of the output signal?
This can be done only if the voltage source is floating (isolated); this pertains also to the SCM7B modules.
Better modules for true differential operation for which a floating source is not needed are the DSCA30/31/40/41. Other modules for this type of operation are the SCM5B30/31/40/41 used with an SCMPB07-x with the I/O COM jumpers Jn removed in the channels for which true differential operation is desired. Both the DSCA and the SCM5B outputs can float +/-50V with respect to power supply common.
Keywords/Phrases: 8B51, reverse input leads, true differential
Why do Dataforth’s linearized thermocouple modules have a low bandwidth of 3-4 Hz?
Our linearized thermocouple modules have a bandwidth of 3-4 Hz in order to reject any induced noise along the sensor line. If a wider bandwidth is needed, a custom module could be designed and manufactured to meet the required specifications. Contact Dataforth at email@example.com to discuss your specific needs.
Is the calibration of Dataforth modules traceable to NIST standards?
Yes, calibration of Dataforth modules is traceable to NIST standards.
Does Dataforth carry any signal conditioners that interface with AC LVDTs?
Although we do not carry signal conditioners that can interface with AC LVDTs, we do have the SCM5B43, 8B43 and DSCA43 which can interface with DC LVDTs.
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 is the input impedance of the DSCA33 module?
For models DSCA33-01 through DSCA33-05, the input impedance is 499kOhm with a <100pF capacitor in parallel with the resistor. For the DSCA33-06 and DSCA33-07, the input impedance is 100 milliohms and 25 milliohms respectively.
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 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
Is an external conversion resistor required in order to use the DSCA32 module?
No, an external conversion resistor is not required in order to use the DSCA32 module. The current/voltage conversion is achieved by an internal resistor as shown in the block diagram in the data sheet.
An external conversion resistor in the case of the DSCA32 could be used to shunt off some of the current from the module and allow a larger input current range; then they could also be used with voltage input modules to convert a non-standard current range into an input voltage range.
Keywords/Phrases: DSCA32, internal resistor, external conversion resistor
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 mount and remove a DIN rail module?
To mount the module, do the following.
With the DIN rail mounted horizontally on a vertical panel, hang the hook at the top rear of the module over the top edge of the DIN rail.
Then rotate the module down so the bottom rear corner of the module touches the bottom edge of the DIN rail.
Then push on the bottom front corner of the module until you hear and feel a click. Push and pull the front of the module to ensure it is securely held on the DIN rail.
To remove the module, do the following.
Using a small screwdriver, insert it into the slot on the movable clip (red for DSCA & DSCT) under the bottom rear corner of the module.
Rotate the body of the screwdriver toward the body of the module until the movable clip disengages the bottom edge of the DIN rail and you can rotate the module upward.
Then you can unhook the module from the top edge of the DIN rail.
Keywords/Phrases: DSCA, DSCT, DIN rail module, mounting, removing
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.
How do I wire up a pulse train to the input of my DSCA45 module?
The DSCA45 accepts TTL signal input across input terminals 6 and 7 (+IN and -IN). A pulse train should be wired across terminals 6 and 7 for proper operation.
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 far can I overrange my DSCA30/31/40/41 module? What will the effects be on the module/output?
The overrange capability is approximately 10% of the input range unless otherwise specified in the datasheet. Beyond that level the output will become nonlinear and will clamp either at a reference or power supply rail. Accuracy and linearity are not guaranteed over the minimum and maximum output.
The module will not be damaged in any way unless the input exceeds the input protection specification, which is 240Vrms continuous.
What happens if I run too much current (say 100mA) through my DSCA32?
A current of 100mA applied to the input of the DSCA32 would be safe. This signal would cause the output to go upscale, but it would not damage the device.
How will the DSCA33 behave with an input signal that is non-sinusoidal, with a quick current spike and zero current for the rest of the waveform?
The DSCA33 would still output the RMS of the waveform. However, the DSCA33 may be less accurate due to the crest factor of such a signal.
Can the DSCA30/31-xx be modified to have a faster response time?
The DSCA30/31-xx series cannot be modified to have a faster response time. However, the DSCA40/41-xx series is the direct equivalent of the DSCA30/31-xx series, but with a wider bandwidth and faster response time.
If a thermocouple is soldered to a lead that has current running through it, how do you avoid affecting the thermocouple signal and subsequent measurement?
The thermocouples must be isolated so current does not come from the circuit under test and run through them. SCM5B, SCM7B, 8B, DSCA, DSCT, MAQ20 all offer the required isolation.
Does the input of the DSCA45 have a high impedance differential amplifier at the input?
Both the TTL and Zero Crossing inputs are single-ended. Both inputs have a 100kOhm input impedance in the power off condition. The TTL input has an input attenuator, so input resistance is approx. 100kOhm. For Zero Crossing input, signals under +/-0.4V don’t clamp the diode so the 100kOhm is in series with the amplifier input which provides high impedance.
Can I measure a small potential on top of a 1500V signal with the DSCA30/31 module?
The DSCA30/31 has an input to output isolation of 1500Vrms, meaning that it is possible to measure small potentials on top of a 1500V common mode voltage. This will not damage the module.
Will I damage the input of my DSCA40-02 if I apply a 12V signal?
All DSCA40 and DSCA30 modules are input protected up to a continuous 240Vrms signal. 12V is well below that rating and will not damage the module.
What size wires do the DSCA modules accept?
DSCA module screw terminals are rated to wire gage AWG: 28 – 12.
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