SCM7B32/33: Isolated Process Current/Voltage Input Modules. Dataforth

Specialists in data acquisition, signal conditioning and data communication

English

The SCM7B32 current input modules accept input signals in the 4-20mA or 0- 20mA ranges from the field and provide a high-level output to the process control system. Current to voltage conversion occurs internal to the module, which is factory calibrated to ensure the highest accuracy.

SCM7B33 voltage input modules accept input signals in the +1V to +5V or 0 to +5V ranges from the field and provide a high-level output to the process control system. As an alternative, the SCM7B33 can be used with an external 250 ohm resistor (Dataforth SCM7BXR1 or equivalent), to accept input signals in the 4-20mA or 0-20mA ranges. Using the external sense resistor allows the module to be removed without disrupting the current loop. All SCM7B33s are shipped with a SCM7BXR1 resistor.

These modules incorporate a five-pole filtering approach to maximize both time and frequency response by taking advantage of both Thomson (Bessel) and Butterworth characteristics. One pole of the filter is on the field side of the isolation barrier; four are on the process control system side.

After the initial field-side filtering (conversion-SCM7B32 only), the input signal is chopped by a proprietary chopper circuit and transferred across the transformer isolation barrier, suppressing transmission of common mode spikes and surges. The signal is then reconstructed and filtered for process control system output.

Modules accept a wide 14 - 35VDC power supply range (+24VDC nominal). Their compact packages (2.13"x1.705"x0.605" max) save space and are ideal for high channel density applications. They are designed for easy DIN rail mounting using any of the "-DIN" backpanels.

Accepts Current or Voltage Input
Provides High-Level Voltage Outputs
1500Vrms Transformer Isolation
Accuracy, ±0.03% of Span Typical, ±0.1% Max
ANSI/IEEE C37.90.1 Transient Protection
Input Protected to 120Vrms Continuous
Noise, 500µV Peak (5MHz), 300µV RMS (100kHz)
CMRR, up to 105dB
80dB Per Decade of Attenuation Above 100Hz
Easy DIN Rail Mounting
CSA Certified, FM Approved
CE and ATEX Compliant

Isolated Process Current/Voltage Input Modules

SCM7B32

Part Number	Input Range	Output Range	Mechanical Format	Internal Power Supply	Isolation Voltage	Isolation Type	Accuracy	Supply Voltage
SCM7B32-01 Order Now	4 to 20 mA	+1 to +5 V	Modular plug-in-board	None	1500 Vrms	Transformer 2-way	±0.03% Span typical, 0.1% Span max	14 to 35 VDC
SCM7B32-01A Order Now	4 to 20 mA	0 to +5 V	Modular plug-in-board	None	1500 Vrms	Transformer 2-way	±0.03% Span typical, 0.1% Span max	14 to 35 VDC
SCM7B32-01D Order Now	4 to 20 mA	0 to +10 V	Modular plug-in-board	None	1500 Vrms	Transformer 2-way	±0.03% Span typical, 0.1% Span max	14 to 35 VDC
SCM7B32-02 Order Now	0 to 20 mA	+1 to +5 V	Modular plug-in-board	None	1500 Vrms	Transformer 2-way	±0.03% Span typical, 0.1% Span max	14 to 35 VDC
SCM7B32-02A Order Now	0 to 20 mA	0 to +5 V	Modular plug-in-board	None	1500 Vrms	Transformer 2-way	±0.03% Span typical, 0.1% Span max	14 to 35 VDC
SCM7B32-02D Order Now	0 to 20 mA	0 to +10 V	Modular plug-in-board	None	1500 Vrms	Transformer 2-way	±0.03% Span typical, 0.1% Span max	14 to 35 VDC

SCM7B33

Part Number	Input Range	Output Range	Bandwidth	Mechanical Format	Isolation Voltage
SCM7B33-01 Order Now	+1 to +5 V	+1 to +5 V	100 Hz	Modular plug-in-board	1500 Vrms
SCM7B33-01A Order Now	+1 to +5 V	0 to +5 V	100 Hz	Modular plug-in-board	1500 Vrms
SCM7B33-01D Order Now	+1 to +5 V	0 to +10 V	100 Hz	Modular plug-in-board	1500 Vrms
SCM7B33-02 Order Now	0 to +5 V	+1 to +5 V	100 Hz	Modular plug-in-board	1500 Vrms
SCM7B33-02A Order Now	0 to +5 V	0 to +5 V	100 Hz	Modular plug-in-board	1500 Vrms
SCM7B33-02D Order Now	0 to +5 V	0 to +10 V	100 Hz	Modular plug-in-board	1500 Vrms

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

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.

Is the optional plug-in conversion resistor required in order to use the SCM7B32 module?

No, the optional plug-in conversion resistor is not shipped with nor is it required in order to use the SCM7B32 module. The current/voltage conversion is achieved by an internal resistor as shown in the block diagram in the data sheet.

Keywords/Phrases: SCM7B32, internal resistors, plug-in conversion resistor

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.

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 the SCM7B32-01 a suitable replacement for the Analog Devices 7B32-01-1?

Yes, the SCM7B32-01 is a direct replacement for the 7B32-01-1. Any application that uses a 7B32-01-1 will support an SCM7B32-01, and vice versa.

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.

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.

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.

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.

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.

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.

Was this content helpful? Yes / No

Model Number	Input Range	Output Range	Bandwidth	Sensor Type	Status*	Comments
SCM7B32-1255 Request Quote	4 TO 20mA	+1 TO +5V	3HZ	CURRENT INPUT	PR	Pin 0 grounded, output limit -0.7 to 5.7V
SCM7B32-1385 Request Quote	4mA TO 20mA	0V to +5V	1500Hz	CURRENT INPUT	QU	Same as SCM7B32-01A with 1500Hz BW
SCM7B32-1705 Request Quote	4mA TO 20mA	0V to +10V	300Hz	CURRENT INPUT	QU	Same as SCM7B32-01D with 300Hz BW
SCM7B32-1807 Request Quote	4mA TO 20mA	0V to +10V	100Hz	CURRENT INPUT	PR	Same as SCM7B32-01D, without encapsulant and top label