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
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
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
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 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
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.”
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
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
What is DSCA32 output resistance?
DSCA32 output resistance is: R out <= 1 Ohm
Keywords/Phrases: output resistance, DSCA32 output resistance
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
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
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
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
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
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)