Siemens SITRANS TW Operator's Manual

SITRANS T measuring instruments for temperature

© Siemens AG 2009

Transmitters for rail mounting

SITRANS TW
four-wire system, universal, HART

3

■

Overview

The user-friendly transmitters for the control room

The SITRANS TW universal transmitter is a further development
of the service-proven SITRANS T for the 4-wire system in a
mounting rail housing. With numerous new functions it sets new
standards for temperature transmitters.

With its diagnostics and simulation functions the SITRANS TW
provides the necessary insight during commissioning and oper­ation. And using its HART interface the SITRANS TW can be
conveniently adapted with SIMATIC PDM to every measurement
task.

All SITRANS TW control room devices are available in a non­intrinsically safe version as well as in an intrinsically safe version
for use with the most stringent requirements.

■

Application

The SITRANS TW transmitter is a four-wire rail-mounted device
with a universal input circuit for connection to the following sen­sors and signal sources:

• Resistance thermometers

• Thermocouple elements

• Resistance-based sensors/potentiometers

• mV sensors

• As special version:

- V sources

- Current sources

The 4-wire rail-mounted SITRANS TW transmitter wire is de­signed for control room installation. It must not be mounted in
potentially explosive atmospheres.

All SITRANS TW control room devices are available in a non­intrinsically safe version as well as in an intrinsically safe version
for use with the most stringent requirements.

■

Function

Features

• Transmitter in four-wire system with HART interface

• Housing can be mounted on 35 mm rail or 32 mm G rail

• Screw plug connector

• All circuits electrically isolated

• Output signal: 0/4 to 20 mA or 0/2 to 10 V

• Power supplies: 115/230 V AC/DC or 24 V AC/DC

• Explosion protection [EEx ia] or [EEx ib] for measurements
with sensors in the hazardous area

• Temperature-linear characteristic for all temperature sensors

• Temperature-linear characteristic can be selected for all tem­perature sensors

• Automatic correction of zero and span

• Monitoring of sensor and cable for open-circuit and short-cir­cuit

• Sensor fault and/or limit can be output via an optional sensor
fault/limit monitor

• Hardware write protection for HART communication

• Diagnostic functions

• Slave pointer functions

Mode of operation

TC

µC

5

9

Power
sup­ply

7

10

D

Output

11

U or I

A

12

6

13

unit

Current test

A

0/4 ... 20 mA

U

H

HART modem/
communicator

RTD

8

A

1

4

D

2

EEPROM

3

The signal output by a resistance-based sensor (two-wire, three­wire, four-wire system), voltage source, current source or ther­mocouple is converted by the analog-to-digital converter
(1, function diagram) into a digital signal. This is evaluated in the
microcontroller (2), corrected according to the sensor character­istic, and converted by the digital-to-analog converter (6) into an
output current (0/4 to 20 mA) or output voltage (0/2 to 10 V). The
sensor characteristics as well as the electronics data and the
data for the transmitter parameters are stored in the non-volatile
memory (3).

AC or DC voltages can be used as the power supply (13). Any
terminal connections are possible for the power supply as a re­sult of the bridge rectifier in the power supply unit. The PE con­ductor is required for safety reasons.

A HART modem or a HART communicator permit parameteriza­tion of the transmitter using a protocol according to the HART
specification. The transmitter can be directly parameterized at
the point of measurement via the HART output terminals (10).

The operation indicator (4) identifies a fault-free or faulty operat­ing state of the transmitter. The limit monitor (9) enables the sig­naling of sensor faults and/or limit violations. In the case of a cur­rent output, the current can be checked on a meter connected
to test socket (12).

Diagnosis and simulation functions

The SITRANS TW comes with extensive diagnosis and simula­tion functions.

Physical values can be defined with the simulation function. It is
thus possible to check the complete signal path from the sensor
input to Inside the control system without additional equipment.
The slave pointer functions are used to record the minimum and
maximum of the plant’s process variable.

3/38

Siemens FI 01 · 2010

SITRANS T measuring instruments for temperature

© Siemens AG 2009

■

Integration

System configuration

SIMATIC S7-400

Control system

U

H

4...20 mA

SITRANS TW
transmitter

HART
communi­cator

Possible system configurations

A

or

HART
modem

ET 200M

or

Load

RS-232-C

The SITRANS TW transmitter as a four-wire rail-mounted device
can be used in a number of system configurations: as a stand­alone version or as part of a complex system environment, e.g.
with SIMATIC S7. All device functions are available via HART
communication.

Communication options through the HART interface:

• HART communicator

• HART modem connected to PC/laptop on which the appropri­ate software is available, e.g. SIMATIC PDM

• HART-compatible control system (e.g. SIMATIC S7-400 with
ET 200M)

SIMATIC PDM

PC/laptop with
SIMATIC PDM

Transmitters for rail mounting

four-wire system, universal, HART

■

Technical specifications

Input

Selectable filters to suppress the
line frequency

Resistance thermometer
Measured variable Temperature
Measured range
Measured span

Sensor type

• DIN IEC 751 Pt100 (DIN IEC 751)

• Acc. to JIS C 1604-81

• Acc. to DIN 43760

• Special type (R

Voltage measurement

Type of connection

Connection
Measuring range limits

Sensor breakage monitoring

Sensor short-circuit monitoring

Resistance-based sensors,
potentiometers

Measured variable Ohmic impedance
Measured range
Measured span
Voltage measurement

Type of connection

Connection
Input range

Sensor breakage monitoring

Sensor short-circuit monitoring

≤ 500 Ω) Multiples or parts of the defined

RTD

50 Hz, 60 Hz, also 10 Hz for spe­cial applications (line frequency
filter is similar with measuring fre­quency)

Parameterizable
Min. 25 °C (45 °F) x 1/scaling

factor

Pt100 (JIS C1604-81)
Ni100 (DIN 43760)

characteristic values can be
parameterized (e.g. Pt500, Ni120)

Temperature-linear, resistance­linear or customer-specific

• Normal connection

• Sum or parallel connection

• Mean-value or differential
connection

2, 3 or 4-wire circuit
Depending on type of connected

thermometer (defined range of
resistance thermometer)

Monitoring of all connections for
open-circuit (function can be
switched off)

Parameterizable response thresh­old (function can be switched off)

Parameterizable
Min. 10 Ω
Resistance-linear or customer-

specific

• Normal connection

• Differential connection

• Mean-value connection

2, 3 or 4-wire circuit
0 ... 6000 Ω;

with mean-value and difference cir­cuits: 0 ... 3000 Ω;

Monitoring of all connections for
open-circuit (function can be
switched off)

Parameterizable response thresh­old (function can be switched off)

SITRANS TW

3

Siemens FI 01 · 2010

3/39

SITRANS T measuring instruments for temperature

© Siemens AG 2009

Transmitters for rail mounting

SITRANS TW
four-wire system, universal, HART

3

Thermocouple elements
Measured variable Temperature
Measured range
Measured span

Measuring range limits

Thermocouple

• Type B Pt30 %Rh/Pt6 %Rh (DIN IEC 584)

• Type C

• Type D

• Type E

• Type J

• Type K

• Type L

• Type N

• Type R

• Type S

• Type T

• Type U

Voltage measurement

Type of connection

Cold junction compensation

Sensor breakage monitoring
mV sensors
Measured variable DC voltage
Measured range
Measured span
Input range
Voltage measurement
Overload capacity of inputs
Input resistance
Sensor current
Sensor breakage monitoring
V sources
Measured variable DC voltage
Measured range
Voltage measurement
Input range/min. span

• Devices with 7NG3242-xxxx1 or
7NG3242-xxxx 0 with U/I plug

• Devices with 7NG3242-xxxx2

• Devices with 7NG3242-xxxx3

Sensor breakage monitoring

Parameterizable
Min. 50 °C (32.22 °F) x 1/scaling

factor
Depend. on type of thermocouple

element

W5 %-Re (ASTM 988)
W3 %-Re (ASTM 988)
NiCr/CuNi (DIN IEC 584)
Fe/CuNi (DIN IEC 584)
NiCr/Ni (DIN IEC 584)
Fe-CuNi (DIN 43710)
NiCrSi-NiSi (DIN IEC 584)
Pt13 %Rh/Pt (DIN IEC 584)
Pt10 %Rh/Pt (DIN IEC 584)
Cu/CuNi (DIN IEC 584)
Cu/CuNi (DIN 43710)
Special type

(-10 mV ≤ UTC ≤ 100 mV)
Temperature-linear, voltage-linear

or customer-specific

• Normal connection

• Sum connection

• Mean-value connection

• Differential connection
None, internal measurement, exter-

nal measurement or predefined
fixed value

Function can be switched off

Parameterizable
Min. 4 mV

-120 ... +1000 mV
Voltage-linear or customer-specific
Max. ± 3.5 V
≥ 1MΩ
Approx. 180 µA
Function can be switched off

Parameterizable
Voltage-linear or customer-specific

-1.2 V ... +10 V/0.04 V

-12 V ... +100 V/0.4 V

-120 V ... +140 V/4.0 V
Not possible

µA, mA sources
Measured variable DC voltage
Measured range
Voltage measurement

Input range/min. span

• Devices with 7NG3242-xxxx4 -12 µA ... +100 µA/0.4 µA

• Devices with 7NG3242-xxxx5

• Devices with 7NG3242-xxxx6

• Devices with 7NG3242-xxxx7 or
7NG3242-xxxx 0 with U/I plug

• Devices with 7NG3242-xxxx8

Sensor breakage monitoring

Output

Output signal Load-independent direct current

Current 0/4 ... 20 mA

• Overrange -0.5 ... +23.0 mA, continuously

• Output range following sensor fault

•Load

• Open-circuit voltage

Voltage 0/2 ... 10 V

• Overrange -0.25 ... +10.75 V, continuously

• Output range following sensor fault

• Load resistance

• Load capacitance

• Short-circuit voltage

• Electrical damping

- Adjustable time constant T

• Current source/voltage source

Sensor fault/limit signalling

Operation indicator

• Limit violation

• Overrange

Relay output

• Switching capacity

• Switching voltage

• Switching current

Overrange

Limit monitoring

• Operating delay 0 ... 10 s

• Monitoring functions of limit
module

• Hysteresis

By operation indicator, relay output

Parameterizable
Current-linear or customer-

specific

-120 µA ... +1000 µA/4 µA

-1.2 mA ... +10 mA/0.04 mA

-12 mA ... +100 mA/0.4 mA

-120 mA ... +1000 mA/4 mA
Not possible

0/4 ... 20 mA, can be switched to
load-independent DC voltage
0/2 ... 10 V using plug-in jumpers.

adjustable

-0.5 ... +23.0 mA, continuously
adjustable

≤ 650 Ω
≤ 30 V

adjustable

-0.25 ... +10.75 V, continuously
adjustable

≥ 1kΩ
≤ 10 nF
≤ 100 mA (not permanently short-

circuit-proof)

0 ... 100 s, in steps of 0.1 s

63

Continuously adjustable within the
total operating range

or HART interface
Flashing signal
Flashing frequency 5 Hz
Flashing frequency 1 Hz
Either as NO or NC contact with

1 changeover contact

≤ 150 W, ≤ 625 VA
≤ 125 V DC, ≤ 250 V AC
≤ DC 2.5 A

Signalling of sensor or line break­age and sensor short-circuit

• Sensor fault (breakage and/or
short-circuit)

• Lower and upper limit

• Window (combination of lower
and upper limits)

• Limit and sensor fault detection
can be combined

Parameterizable between 0 and
100 % of measuring range

3/40

Siemens FI 01 · 2010

SITRANS T measuring instruments for temperature

© Siemens AG 2009

Transmitters for rail mounting

SITRANS TW

four-wire system, universal, HART

Power supply

Universal power supply unit 115/230 V AC/DC or 24 V AC/DC
Tolerance range for power supply

• With 115/230 V AC/DC PSU 80 ... 300 V DC; 90 ... 250 V AC

• With 24 V AC/DC PSU

Tolerance range for mains fre­quency

Power consumption with

• 230 V AC ≤ 5 VA

• 230 V DC

• 24 V AC

• 24 V DC

Electrical isolation

Electrically isolated circuits Input, output, power supply and

Working voltage between all electri­cally isolated circuits

Measuring accuracy

Measurement error

• Error in the internal cold junction ≤ 3°C ± 0,1 °C/10 °C

• Error of external cold junction ter­minal 7NG3092-8AV

• Digital output

• Analog output I

Influencing effects (referred to the
digital output)

• Temperature drift

• Long-term drift

Influencing effects referred to the
analog output I

• Temperature drift

• Power supply

• Load with current output

• Load with voltage output

• Long-term drift (start-of-scale
value, span)

Response time (T
cal damping)

Electromagnetic compatibility

Certificate and approvals

ATEX To DIN EN 50014: 1997,

Intrinsic safety to EN 50 020

• for 7NG3242-xAxxx II (1) G D [EEx ia/ib ] IIB

• for 7NG3242-xBxxx

EC-Type Examination Certificate

or U

AN

or U

AN

AN

without electri-

63

AN

18 ... 80 V DC; 20.4 ... 55.2 V AC
(in each case interruption-resistant
up to 20 ms in the complete toler­ance range)

47 ... 63 Hz

≤ 5 W
≤ 5 VA
≤ 5 W

sensor fault/limit monitoring output
are electrically isolated from one
another. The HART interface is
electrically connected to the out­put.

The voltage U
terminals must not exceed 300 V

(≤ 5.4 °F ± 0,18 °F/18 °F)
≤ 0.5 °C ± 0,1 °C/10 °C

(≤ 0.9 °F ± 0.18 °F/18 °F)
See "Digital error"
≤ 0.05 % of span in addition to

digital error
Compared to the max. span:

≤ 0.08 %/10 °C (≤ 0.08 %/18 °F)
≤ 0.2 % in the range -10 ... +60 °C

(14 ... 140 °F)
≤ 0.1 %/year
Compared to the span:

≤ 0.08 %/10°C (≤ 0.08 %/18 °F)
≤ 0.2 % in the range -10 ... +60 °C

(14 ... 140 °F)

≤ 0.05 %/10 V
≤ 0.05 % with change from

50 ... 650 Ω
≤ 0.1 % with change in load current

from 0 ... 10 mA

≤ 0.03 %/month

≤ 0.2 s

According to EN 61326 and
NAMUR NE21

EN 50020: 1994

II (1) G D [EEx ia/ib ] IIC
TÜV (German Technical Inspec-

torate) 01 ATEX 1675

between any two

eff

Rated conditions

Installation conditions
Location (for devices with explo-

sion protection)

• Transmitters Outside the potentially explosive

•Sensor

Ambient conditions
Permissible ambient temperature -25 ... +70 °C (-13 ... +158 °F)
Permissible storage temperature
Climatic class

• Relative humidity 5 ... 95 %, no condensation

Design

Weight Approx. 0.24 kg (0.53 lb)
Enclosure material
Degree of protection to IEC 529
Degree of protection to VDE 0100
Type of installation

Electrical connection/process con­nection

Parameterization interface

Protocol HART, version 5.9
Load with connection of

• HART communicator 230 ... 650 Ω

•HART modem
Software for PC/laptop

atmosphere
Within the potentially explosive

atmosphere zone 1 (also in zone 0
in conjunction with the prescribed
protection requirements for the
sensor)

-40 ... +85 °C (-40 ... +185 °F)

PBT, glass-fibre reinforced
IP20
Protection class I
35-mm top hat rail (1.38 inch)

(DIN EN 50022) or 32-mm G-type
rail (1.26 inch) (DIN EN 50035)

Screw plug connectors,
max. 2.5 mm² (0.01 inch²)

230 ... 500 Ω
SIMATIC PDM version V5.1 and

later

3

Siemens FI 01 · 2010

3/41