Each SCM5B33 True RMS input module provides a single channel of AC input which is converted to its True RMS DC value, filtered, isolated, amplified, and converted to a standard process voltage or current output.

The SCM5B modules are designed with a completely isolated computer side circuit which can be floated to ±50V from Power Common, pin 16. This complete isolation means that no connection is required between I/O Common and Power Common for proper operation of the output switch. If desired, the output switch can be turned on continuously by simply connecting pin 22, the Read-Enable pin, to I/O Common, pin 19.

The field voltage or current input signal is processed through a pre-amplifier and RMS converter on the field side of the isolation barrier. The converted DC signal is then chopped by a proprietary chopper circuit and transferred across the transformer isolation barrier, suppressing transmission of common mode spikes and surges. The computer side circuitry reconstructs, filters and converts the signal to industry standard outputs. Modules are powered from +5VDC, ±5%.

For current output models, an external loop supply of 4.2V to 26V is required. The loop supply connection, with series load, is between Pin 20 (+) and Pin 19 (-).

Read our Application Note 101, Measuring RMS Values of Voltage and Current.
  • Interfaces RMS Voltage (0 – 300V) or RMS Current (0 – 5A)
  • Designed for Standard Operation with Frequencies of 45Hz to 1000Hz (Extended Range to 20kHz)
  • Compatible with Standard Current and Potential Transformers
  • Industry Standard Output of either 0-1mA, 0-20mA, 4-20mA, 0-5V or 0-10VDC
  • ±0.25% Factory Calibrated Accuracy (Accuracy Class 0.2)
  • 1500Vrms Continuous Transformer Isolation
  • Input Overload Protected to 480V Max (Peak AC & DC) or 10A RMS Continuous
  • ANSI/IEEE C37.90.1 Transient Protection
  • CSA Certified, CE and ATEX Compliant
Isolated True RMS Input Modules

SCM5B33 Devices


Part Number Input RangeOutput RangeMechanical FormatIsolation VoltageIsolation Type
0 to +100 mV 0 to +5 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +100 mV 0 to 1 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +100 mV 4 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +100 mV 0 to +10 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +100 mV 0 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +1 V 0 to +5 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +1 V 0 to 1 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +1 V 4 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +1 V 0 to +10 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +1 V 0 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +10 V 0 to +5 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +10 V 0 to 1 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +10 V 4 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +10 V 0 to +10 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +10 V 0 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +150 V 0 to +5 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +150 V 0 to 1 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +150 V 4 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +150 V 0 to +10 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +150 V 0 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +300 V 0 to +5 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +300 V 0 to 1 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +300 V 4 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +300 V 0 to +10 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to +300 V 0 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 1 A 0 to +5 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 1 A 0 to 1 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 1 A 4 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 1 A 0 to +10 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 1 A 0 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 5 A 0 to +5 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 5 A 0 to 1 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 5 A 4 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 5 A 0 to +10 V Modular plug-in-board 1500 Vrms Transformer 3-way
0 to 5 A 0 to 20 mA Modular plug-in-board 1500 Vrms Transformer 3-way

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

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.

With the SCM5B33-06 and SCM5B33-07, what are the included jumpers for?
You install one jumper from the +EXC to the +In terminals and the other jumper from the –EXC to the –In terminals. This allows the traces on the backpanel and the traces in the module to the current shunt to share the excess current.

Keywords/Phrases: SCM5B33-06, SCM5B33-07, included jumpers, excess current

Do you know if the SCM5B33 can read the current / voltage for a system operating at 16.66 Hz?
It is possible, but less than 45Hz requires design of a custom module with 7Hz being the low limit.
Keywords/Phrases: SCM5B33, SCM5B33 low frequency, SCM5B33 lower frequency.

Can you explain what is the difference between the “Standard frequency range” and the “Extended frequency range” for the SCM5B33 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 5B33 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: 5B RMS, 5B True RMS, 5B RMS input module, 5B True RMS input module, 5B33

I have an SCM5B33 module, what is the total power consumption?
The max base power in all 5B33 modules is +5VDC x 140mA(max) = 700mW.

For Vout models, 5B33-01 to 5B33-07, add: 5V x 2mA = 10mW.
For Vout models, 5B33-01D to 5B33-07D, add: 10V x 2mA = 20mW.
For 0 to 1mA current loop output modules, 5B33-01B to 5B33-07B add 3mW.
For 0/4 to 20mA current loop output modules, 5B33-01C,E to 5B33-07C,E add 60mW.

The 5B33-06 has a 0.1? current shunt. Add 1A^2 x0.1? =100mW.
The 5B33-07 has a 0.025? current shunt. Add 5A^2 x0.025? = 625mW.

Keywords/Phrases: 5B33 power, 5B33 total power, 5B33 power consumption, 5B33 total power consumption, mW, watt, watts, milliwatts, heat, dissipation

I have an SCM5B33 module, what is the accuracy error between 0-10% span?
In Note 4, For 0-10% Span measurements add 0.25% accuracy error (-02 through -07) or 1.00% accuracy error (-01). Accuracy error includes linearity, hysteresis and repeatability but not source or external shunt inaccuracy (if used).

Keywords/Phrases: 5B RMS, 5B True RMS, 5B RMS input module, 5B True RMS input module, 5B33 accuracy

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

Will the isolation on the SCM5B modules support a discharge of 1500VDC without damaging anything connected to the output?
Yes, the SCM5B modules are isolated up to 1500 Vrms, which means that if the common mode voltage between the field side and system side is limited to 1500Vrms, the device will be protected.

However, the input protection for SCM5B modules (i.e., the voltage across the +IN and -IN input terminals) is 240Vrms max.

Do you have any SCM5B modules with a 50kHz bandwidth?
None of our standard SCM5B modules have a 50kHz bandwidth. However, it is possible to order a custom SCM5B module with 50kHz bandwidth. Keep in mind that new customs require a 10 pc minimum order and are subject to extra design fees.

Do you have an MTBF figure for the SCM5B39? What are the main failure modes?
The failure rate calculations for our SCM5B modules can be found in our application note AN503: https://www.dataforth.com/catalog/pdf/an503.pdf

There are no dominant failure modes.

What is the required resistance for jumpers J1 through J4 on my SCM5B backpanel?
J1-J4 on the SCM5B backpanels are jumper cables, so they should have 0 ohm resistance.

I just received an SCMPB01 back panel. How should I configure jumpers J1 through J4 for my application?
The factory configuration for jumpers J1 through J4 is the optimal configuration for most applications. If for some reason this jumper configuration will not work/is not working in your application, see our application note AN502 "Ground Connections and Host System Interfaces" for other valid jumper configurations and what situations you would use them.

Should I ground my sensor wire shield to the 10-32 ground post on the SCMPB01?
It is not recommended to ground the sensor wire shield to the 10-32 ground post on the SCMPB01 because that is the system side ground, while the sensor wire is on the field side. The sensor wire shield should be grounded to the field side ground, which varies based on the signal conditioner you are using. Please see the "Shield Grounding" application note for more information.

Do I need to purchase the SCMXCJC with my SCMPB03?
No, the SCMPB03 comes with the CJC built into the backpanel.

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.

Do SCM5B modules with outputs scaled up to 10V have separate power requirements from their 5V counterparts?
No, all SCM5B modules have the same power requirements (5VDC) regardless of their I/O specifications. The power supply current draw of different products in the SCM5B line may vary.

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.

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.

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.

Can I use an SCM5B module with my OM5-BP-SKT-C?
Yes, any of our SCM5B modules are able to be mounted and operated on Omega's OM5-BP-SKT-C board.

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.