Impulse SCM5B34 User Manual

SCM5B34

Linearized 2- or 3-Wire RTD Input Modules

Description

Each SCM5B34 RTD input module provides a single channel of RTD input

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

analog voltage output (Figure 1). This voltage output is logic switch controlled,

which allows these modules to share a common analog bus without the

requirement of external multiplexers.

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.

RTD excitation is provided from the module by two matched current sources.

When using a three-wire RTD, this method allows an equal current to flow in

each RTD lead, which cancels the effects of lead resistances. The excitation

currents are very small (0.25mA for 100

Cu) which minimizes self-heating of the RTD.

Signal filtering is accomplished with a six-pole filter which provides 95dB of

normal-mode-rejection at 60Hz and 90dB at 50Hz. Two poles of this filter are

on the field side of the isolation barrier, and the other four are on the computer

side. After the initial field-side filtering, the input signal is chopped by a proprietary

chopper circuit. Isolation is provided by transformer coupling, again using a

proprietary technique to suppress transmission of common mode spikes or

surges. The module is powered from +5VDC, ±5%.

Ω Pt and 120Ω Ni, and 1.0mA for 10Ω

Isolated Analog Signal Conditioning Products

▲

Features

 Interfaces to 100Ω Platinum, 10Ω Copper,

or 120

Ω Nickel RTDs

 Linearizes RTD Signal

 High Level Voltage Outputs

 1500Vrms Transformer Isolation

 ANSI/IEEE C37.90.1 Transient Protection

 Input Protected to 240VAC Continuous

 160dB CMR

 95dB NMR at 60Hz, 90dB at 50Hz

 CSA Certified, FM Approved, CE and ATEX

Compliant

 Mix and Match SCM5B Types on Backpanel

SCM5B

A special input circuit on the SCM5B34 modules provides protection against

accidental connection of power-line voltages up to 240VAC.

Figure 1: SCM5B34 Block Diagram

For information call 800-444-7644

Isolated Analog Signal Conditioning Products

SCM5B

Specifications

Module

Input Range Limits 200°C to +850°C (100Ω Pt)

Input Resistance

Normal 50MΩ Power Off 40kΩ Overload 40kΩ

Input Protection

Continuous 240Vrms max

Transient ANSI/IEEE C37.90.1

Sensor Excitation Current

100Ω Pt, 120Ω Ni 0.25mA 10Ω Cu 1.0mA

Lead Resistance Effect

100Ω Pt, 120Ω Ni ±0.02°C/Ω 10Ω Cu ±0.2°C/Ω

CMV, Input to Output

Continuous 1500Vrms max

Transient ANSI/IEEE C37.90.1

CMR (50 or 60Hz) 160dB

NMR 95dB at 60Hz, 90dB at 50Hz

Accuracy See Ordering Information

Conformity Error

Stability

Input Offset ±0.01°C/°C

Output Offset ±20µV/°C

Gain ±35ppm of Reading/°C

Noise

Input, 0.1 to 10Hz 0.2µVrms

Output, 100kHz 200µVrms

Bandwidth, 3dB 4Hz

Response Time, 90% Span 0.2s

Output Range See Ordering Information

Output Resistance 50Ω

Output Protection Continuous Short to Ground

Output Selection Time 6µs at C

(to ±1mV of V

Output Current Limit +8mA

Output Enable Control

Max Logic 0 +0.8V

Min Logic 1 +2.4V

Max Logic 1 +36V

Input Current 0,1 0.5µA

Open Input Response Downscale

Open Input Detection Time 3s

Power Supply Voltage +5VDC ±5%

Power Supply Current 30mA

Power Supply Sensitivity

100Ω Pt, 120Ω Ni 0.2°C/V 10Ω Cu 0.5°C/V

Mechanical Dimensions 2.28" x 2.26" x 0.60"

(h)(w)(d) (58mm x 57mm x 15mm)

Environmental

Operating Temperature Range 40°C to +85°C

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

Storage Temperature 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 Perfor mance B

Typical at TA=+25°C and +5V power

(3)

)

OUT

SCM5B34

80°C to 320°C (120Ω Ni)

100°C to 260°C (10Ω Cu)

±0.025% Span

= 0 to 2000pF

load

Ordering Information

Model Input Range Accuracy

ΩΩ

100

Ω Pt **

ΩΩ

Output Range



SCM5B34-01 100°C to +100°C 3, 4 ±0.12°C

(148°F t o +212°F)

SCM5B34-02 0°C to +100°C 3, 4 ±0.06°C

(+32°F to +212°F)

SCM5B34-03 0°C to +200°C 3, 4 ±0.12°C

(+32°F to +392°F)

SCM5B34-04 0°C t o +600°C 3, 4 ±0.36°C

(+32°F to +1112°F)

SCM5B34-05 -100°C to +200°C 3, 4 ±0.18°C

(-148°F to +392°F)

ΩΩ

Ω Cu **

(1)

ΩΩ

SCM5B34C-01 0°C to +120°C 3, 4 ±0.23°C

(10

Ω at 0°C)

(+32°F to +248°F)

SCM5B34C-02 0°C to +120°C 3, 4 ±0.23°C

(10

Ω at 25°C)

(+32°F to +248°F)

SCM5B34C-03 0°C to +160°C 3, 4 ±0.32°C

(10

Ω at 0°C)

(+32°F to +320°F)

ΩΩ

120

Ω Ni **

ΩΩ

SCM5B34N-01 0°C to +300°C 3, 4 ±0.23°C

(+32°F to +572°F)

**RTD Standards

Type Alpha Coefficient DIN JIS

Ω Pt 0.00385 DIN 43760 JIS C 1604-1989

100

120Ω Ni 0.00672 10ΩCU 0.004274







Output Ranges Available

Output Range Part No. Suffix Example

3. 0V to +5V NONE SCM5B34-01

4. 0V to +10V D SCM5B34-01D

NOTES:

(1) "Ω" refers to the resistance in one lead. (2) Includes conformity, hysteresis and repeatability.

(3) Conformity error is ±0.05% Span for SCM5B34N-01

(2)

SCM5B

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