8B modules are an optimal solution for monitoring real-world process signals and providing high-level signals to a data acquisition system. Each 8B38 module isolates, filters, and amplifies a full-bridge strain gage input signal and provides an analog voltage output.
The 8B38 can interface to transducers with a nominal resistance of 100Ω to 2kΩ. Bridge excitation is provided from the module with a stable 10.00V or 3.33V source. Full scale sensitivities of 2mV/V and 3mV/V are offered as standard.
Signal filtering is accomplished with a 5-pole filter optimized for time and frequency response which provides 100dB per decade of normal-mode rejection above the filter cutoff frequency. One pole of this filter is on the field side of the isolation barrier for anti-aliasing, and the other four are on the system side.
A special input circuit on the 8B38 module provides protection against accidental connection of power-line voltages up to 240VAC. Clamp circuits on the I/O and power terminals protect against harmful transients.
Isolation is provided by transformer coupling to suppress transmission of common mode spikes or surges. The module is powered from +5VDC, ±5%.
The modules are designed for installation in Class I, Division 2 hazardous locations and have a high level of immunity to environmental noise.
Frequently Asked Questions
Can SCM5B modules be hot swapped?
Not just SCM5B modules, but any signal conditioning module series and MAQ20 I/O modules can be hot swapped. A minimal amount of signal settling time may result, but there will be no damage to the device.
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 firstname.lastname@example.org
Is the calibration of Dataforth modules traceable to NIST standards?
Yes, calibration of Dataforth modules is traceable to NIST standards.
Analog Devices announced a last time buy and discontinuance of their signal conditioning modules. Can I replace them with Dataforth signal conditioning modules?
Yes, in general, Dataforth signal conditioning modules are a direct replacement for all Analog Devices signal conditioning modules. e.g. "SCM5B35-xx: Linearized 4-Wire RTD Input Modules" will replace Analog Devices "5B35: Isolated 4 Wire RTD Input Signal Conditioning Module".
Please note that Dataforth signal conditioning modules are RoHS II compliant.
What is the recommended power supply for Dataforth SCM5B and 8B modules?
The recommended power supply for the Dataforth SCM5B and 8B modules are the linear power supplies in our SCMXPRT/SCMXPRE series. The SCMXPRT/SCMXPRE power supplies output 5V and have options for 1A output current (SCMXPRT-001) or 3A output current (SCMXPRT-003).
The SCMXPRE series is identical to its SCMXPRT counterpart, but is configured for European voltage standards.
The SCMXPRT-001/SCMXPRE-001 both have the option for DIN rail mounting as well (SCMXPRT-001D/SCMXPRE-001D).
Other power supplies that meet that power requirements of the SCM5B and 8B modules can be used as well, but it is strongly recommended to use a linear power supply rather than a switch-mode power supply. Switching power supplies can add noise artifacts to the output of your modules.
Can I power multiple 8B backplanes off of a single power supply?
You can use a single 5V power supply to power multiple backplanes, but you need to be aware of the current rating of your power supply and the current draw of your 8B modules. The current rating of your power supply needs to be greater than the total current draw of all the modules in your system (ideally 1.5x the total current draw). You can check the current draw of various 8B modules by checking their datasheets.
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.
If I purchase a backplane with no CJC, will I still be able to use modules that require the CJC enable jumper to be installed?
Yes. Backplanes with no CJC will still come with the CJC enable installed on the backplane.
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.
If I were to put a 120 ohm bridge onto an 8B38-02 (range of 300 ohm to 2K ohm), what happens to the supply voltage and will the system work?
If you were to put a 120ohm bridge into an 8B38-02 the excitation voltage won’t regulate, and it won’t provide the proper amount of excitation. The load range must be in the specified range.
Does the 8B series backplanes identify the module slots on the PWB via silkscreen or other methods? Does it also mark the terminal blocks +/- inputs?
The 8B backpanels identify the module slots and their associated terminal block with silkscreen text (this includes the +/- inputs). The text is descriptive and matches up with the diagrams in our datasheets.
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.
If I don’t have an 8BPWR-2, can I use a +5VDC power supply to power my 8B backplane?
Yes, you can. The 8BPWR-2 is not required to power the 8B backplanes, it is used in situations where you don't have a +5VDC power supply and need to regulate the voltage of whatever current power supply you are using down to +5VDC so that it can be used for the 8B backplane.
Please make sure when choosing your +5VDC power supply that the current rating of the supply is acceptable for the total current draw of your system.
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
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.
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.
Why do only a few 8B modules have a +/-5V output?
Some 8B modules (such as 8B34 and 8B47) cannot have bipolar output due to limitations in the internal linearization circuitry.
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.
If someone accidentally connected a powered sensor (0-5V analog signal) to the input of an 8B38 would it damage it?
The 8B38 has an input protection of 240VAC continuous, so a 0-5V input will not damage the device. You can apply a continuous signal of up to 240VAC before the input will start to get damaged.
What is the correct backpanel for my 8B38 module?
Any of the backpanels in the 8B series will work for the 8B38 module. In fact, any of the 8B modules can be mounted to any of the 8B backpanels.
Is the SCMXPRT-003 DIN rail mountable?
The SCMXPRT-001 has an option for DIN rail mounting (part number: SCMXPRT-001D) but the SCMXPRT-003 does not. Instead, it can be mounted on the SCMXRK-002 which is a 19 inch metal rack for mounting the SCMXPRT-003 as well as various Dataforth backpanels and the SCMXIF interface board.
Is the DSCA38-02 compatible with a load cell with a sensitivity of 2mV/V? How would it affect measurements?
For the DSCA38-02, the +/-30mV range maps to the +/-10V output; -30mV input = -10V output and +30mV input = +10V output. The sensitivity is a specification that refers to the sensitivity of the strain gauges that are fully compatible with the module.
If a DSCA38-02 is used with a load cell that has 2mV/V sensitivity, then the module's output is limited to two thirds of the full range (i.e. +/-20mV). This assumes the load cell has a rated excitation voltage of 10V. This reduced output range might be okay depending on the specific use case.
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.
Was this content helpful?
Don't see an answer to your question?
If you have a question that is not answered here, please submit your question using our Online Technical Support Assistance.
View Dataforth cross-reference data.
- No cross reference is available.
The information available through this competitive cross reference guide are based upon product catalog information obtained from a variety of sources. The competitive cross reference information is being provided to you free of charge for your use. While Dataforth Corp has used reasonable efforts to ensure data accuracy, Dataforth Corp does not guarantee that it is error-free, nor does Dataforth Corp make any other representation, warranty or guarantee that the information is accurate, correct, reliable or up-to-date. Dataforth Corp expressly disclaims all implied warranties regarding this information, including but not limited to any implied warranties of merchantability or fitness for a particular purpose.
This information is provided only as a convenience on an "as is" basis and Dataforth Corp. or its representatives or distributors are not responsible for any incorrect, inaccurate, or incomplete information. You are solely responsible for (1) selecting the appropriate Dataforth products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable standards, and any other safety, security, or other requirements.