Impulse SCM7B36 User Manual

Isolated Process Control Signal Conditioning Products

SCM7B36

Isolated Potentiometer Input Modules

Description

Each SCM7B36 Potentiometer input module provides a single channel of

resistance input which is filtered, isolated, amplified, and converted to a high level

analog voltage output.

The SCM7B36 module interfaces to slidewires and potentiometers in both two

or three wire configuration and incorporates a five-pole filtering approach to

maximize both time and frequency response by taking advantage of both 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. In the 3-Wire

configuration, lead resistance compensation is provided if the resistance of the

x lead is closely equivalent to that of the + lead. Internal to the module,

measurement error due to lead resistance is canceled.

In response to the low level current excitation, and after initial field-side filtering,

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.

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Features

 Industrys First 7B Potentiometer Input

Module

 Interfaces 100

 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

 CSA Certified, FM Approved

 CE and ATEX Compliant

Ω to 10kΩ Potentiometers

SCM7B

Six standard input resistance ranges are offered, from 100

output ranges available: 0-5V, 1-5V, and 0-10V. Modules accept a wide 14-

35VDC power supply range (+24VDC nominal). Their compact packages

(2.13" x 1.705" x 0.605" max.) save space and are ideal for high channel

density applications. They are designed for easy DIN rail mounting using any

of Dataforths -DIN backpanels.

Ω to 10kΩ, with three

Figure 1: SCM7B36 Block Diagram

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Isolated Process Control Signal Conditioning Products

SCM7B

Specifications

Module

Typical at 25°C and +24VDC

SCM7B36

Input Range (See Ordering Information)

Protection

Continuous 120Vrms max

Transient ANSI/IEEE C37.90.1

Sensor Excitation Current 65µA (10kΩ) to 260µA (100Ω)

Lead Resistance Effect (3-Wire)

(1)

-01 thru -04 : ±0.005Ω/Ω

-05 : ±0.02Ω/Ω

-06 : ±0.04Ω/Ω

Output Range

(See Output Range)

Effective Available Power

(2) 

(2)

40mW

Resistance < 1Ω

Protection Continuous Short-to-Ground

Voltage/Current Limit ±12V, ±14mA

CMV (Input to Output)

Continuous 1500Vrms

Transient ANSI/IEEE C37.90.1

CMRR (50 or 60Hz) 120dB

Accuracy

Nonlinearity

(3)

(4)

±0.03% Span typical,

±0.1% Span max

±0.01% Span typical,

±0.02% Span max

Stability (-40°C to +85°C)

Input Offset ±0.01Ω/°C

Output Offset ±30µV/°C

Gain ±60ppm/°C

Noise Peak at 5MHz B/W 1mV

RMS at 10Hz to 100kHz B/W 250µV

Peak at 0.1Hz to 10Hz B/W 1µV RTI

Open Input Response

+ Lead Upscale

 Lead Non-deterministic

x Lead Downscale

Open Input Detection Time <5s

Frequency and Time Response

Bandwidth, -3dB 3Hz

NMR (50/60Hz) 80/85dB

Step Response, 0 to 90% 250ms

Supply Voltage 14-35VDC

2

Current

Sensitivity ±0.0001%/%V

12mA

S

Mechanical Dimensions 2.13" x 1.705" x 0.605", max

(h)(w)(d) 54.1mm x 43.3mm x 15.4mm max

Environmental

Operating Temp. Range -40°C to +85°C

ATEX Group II, Category 3 -20°C to +40°C

Storage Temp. Range -40°C to +85°C

Relative Humidity 0 to 95% Noncondensing

Emissions EN61000-6-4 ISM, Group 1

Radiated, Conducted Class A

Immunity EN61000-6-2 ISM, Group 1

R F Performance A ±0.5% Span Error

ESD, EFT, Surge, Voltage Dips Performance B

NOTES:

(1) Lead resistance effect is given for the condition of not having the NTC thermistor installed in the

backpanel. As a general rule; as long as the lead resistance of the (+) lead matches the parallel

combination of the thermistor and lead resistance in the (X) lead, the given specifications apply.

(2) Output Range and Supply Current specifications are based on minimum output load resistance.

Minimum output load resistance is calculated by V

Power that guarantees output range and accuracy specifications.

(3) Accuracy includes the effects of repeatability, hysteresis, and linearity, but does not include sensor

accuracy.

(4) Nonlinearity is calculated using the best-fit straight line method.

2

/PE, where PE is the output Effective Available

OUT

Ordering Information

Model Input Range

SCM7B36-01 0 - 100Ω
SCM7B36-02 0 - 200Ω
SCM7B36-03 0 - 500Ω
SCM7B36-04 0 - 1kΩ
SCM7B36-05 0 - 5kΩ
SCM7B36-06 0 - 10kΩ







Output Ranges Available

Output Range Part No. Suffix Example

+1 to +5V NONE SCM7B36-01

0 to +5V A SCM7B36-01A

0 to +10V D SCM7B36-01D

SCM7B

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