Acromag TT231-0600 User manual

USB Programmable, DIN Rail Mount
Thin Temperature Transmitter
Model TT231-0600
RTD Input, Two-Wire Transmitter
USER’S MANUAL
ACROMAG INCORPORATED Tel: [phone]
30765 South Wixom Road Fax: [phone]
Wixom, MI 48393-7037 U.S.A. email: [email protected]
Copyright 2012, Acromag, Inc., Printed in the USA.
Data and specifications are subject to change without notice. 8500-935C

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 2 - http://www.acromag.com
- 2 -
http://www.acromag.com
Table of Contents
GETTING STARTED
DESCRIPTION.......................................................................................................4
Key Features........................................................................................................................4
Application ..........................................................................................................................4
Mechanical Dimensions .......................................................................................................5
DIN Rail Mounting & Removal..............................................................................................5
ELECTRICAL CONNECTIONS............................................................................6
Sensor Input Connections ....................................................................................................7
Output/Power Connections .................................................................................................8
Earth Ground Connections .................................................................................................10
USB Connections................................................................................................................11
CONFIGURATION SOFTWARE...................................................................... 12
Quick Overview .................................................................................................................12
TECHNICAL REFERENCE
OPERATION STEP-BY-STEP.......................................................................... 14
Connections.......................................................................................................................14
Configuration.....................................................................................................................15
Calibrate I/O Range Selection ............................................................................................19
Zero, Full-Scale, & Linearizer Calibration Procedure .................................................................. 20
Pt RTD Resistance Versus Temperature Table............................................................................ 22
Over-Scale & Under-Scale Thresholds.................................................................................23
Break Detection.................................................................................................................24
Read Status .......................................................................................................................24
Reset Unit..........................................................................................................................25
Restore Factory Settings ....................................................................................................25

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 3 - http://www.acromag.com
- 3 -
http://www.acromag.com
BLOCK DIAGRAM ............................................................................................. 27
How It Works.....................................................................................................................27
TROUBLESHOOTING....................................................................................... 30
Diagnostics Table...............................................................................................................30
Service & Repair Assistance ...............................................................................................33
ACCESSORIES .................................................................................................... 34
Software Interface Package................................................................................................34
USB Isolator.......................................................................................................................34
USB A-B Cable....................................................................................................................34
USB A-mini B Cable ............................................................................................................34
SPECIFICATIONS .............................................................................................. 35
Model Number ..................................................................................................................35
Input .................................................................................................................................35
Output...............................................................................................................................37
USB Interface.....................................................................................................................38
Enclosure & Physical ..........................................................................................................39
Environmental ...................................................................................................................39
Agency Approvals ..............................................................................................................40
Reliability Prediction..........................................................................................................40
Configuration Controls.......................................................................................................40
REVISION HISTORY ......................................................................................... 41
All trademarks are the property of their respective owners.
IMPORTANT SAFETY CONSIDERATIONS
You must consider the possible negative effects of power, wiring, component, sensor, or software failure in the design of
any type of control or monitoring system. This is very important where property loss or human life is involved. It is
important that you perform satisfactory overall system design and it is agreed between you and Acromag, that this is your
responsibility.
The information of this manual may change without notice. Acromag makes no warranty of any kind with regard to
this material, including, but not limited to, the implied warranties of merchantability and fitness for a particular
purpose. Further, Acromag assumes no responsibility for any errors that may appear in this manual and makes no
commitment to update, or keep current, the information contained in this manual. No part of this manual may be
copied or reproduced in any form without the prior written consent of Acromag, Inc.

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 4 - http://www.acromag.com
- 4 -
http://www.acromag.com
GETTING STARTED
DESCRIPTION
Symbols on equipment:
Means “Refer to User’s Manual
(this manual) for additional
information”.
The TT231-0600 is an ANSI/ISA Type II transmitter designed to interface with a
Platinum RTD sensor (Resistance Temperature Detector), or resistance input, and
modulate a 4-20mA current signal for a two-wire current loop. This unit is setup
and calibrated using configuration software and a USB connection to Windows-
based PC’s (Windows XP and later versions only). The unit provides RTD sensor
excitation, linearization, lead-wire compensation, and lead break or sensor burnout
detection. It also offers an adjustable input and output range with degrees F or C
selection and adjustable loop alarm levels.
Key Features
Pt RTD or Linear Resistance input support.
Adjustable input range with spans up to 850°C (1562°F) or 900Ω.
Adjustable input excitation, linearization, and output range.
Fully analog signal path (input signal is not digitized).
Digitally setup and calibrated w/ Windows software via USB.
Thin 12.5mm wide enclosure for high-density DIN-rail mounting.
Converts sensor signal with a single differential measurement.
Very fast output response.
Supports Degrees Celsius or Fahrenheit Temperature Ranges.
Extra output connections support Sink or Source output wiring.
Connects to two, three, or four wire sensors.
Lead-wire compensation (3-wire).
Up or down-scale lead-break/burnout detection.
Adjustable output error/alarm levels outside of operating range.
Convenient non-polarized two-wire current loop powered.
Provides a linearized or non-linearized output response.
Adjustable under-range and over-range levels. Namur compliant.
High measurement accuracy and linearity.
Wide ambient temperature operation.
Hardened For Harsh Environments.
CE Approved.
UL/cUL Class 1, Division 2 Approved.
Application
For additional information on
these devices and related topics,
please visit our web site at
www.acromag.com and download
our whitepaper 8500-904,
Introduction to Two-Wire
Transmitters. Also see 8500-917,
The Basics of Temperature
Measurement Using RTD’s.
This transmitter is designed for high-density mounting on T-type DIN rails. Its non-
isolated input is intended to mate with non-grounded, 100Ω, Pt RTD temperature
sensors or resistive elements. It provides an output current linearized to the RTD
sensor temperature. Optionally, it can support simple resistance input and drive an
output current linear to sensor resistance.
The output signal is transmitted via a two-wire, 4-20mA current loop. The two-wire
current signal can be transmitted over long distances with high noise immunity.
Sensor lead-break detection and the inherent 4mA live-zero output offers
convenient I/O fault detection, should an I/O wire break. Extra connections at the
output of this model allow it to be optionally wired for a “sourced” 4-20mA output
configuration (see Output/Power Connections).
!

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 5 - http://www.acromag.com
- 5 -
http://www.acromag.com
Mechanical Dimensions
Units may be mounted to 35mm
“T” type DIN rail (35mm, type
EN50022), and side-by-side on 0.5-
inch centers.
WARNING: IEC Safety Standards
may require that this device be
mounted within an approved
metal enclosure or sub-system,
particularly for applications with
exposure to voltages greater than
or equal to 75VDC or 50VAC.
DIN Rail Mounting & Removal
Refer to the following figure for attaching and removing a unit from the DIN rail. A
spring loaded DIN clip is located on the input side bottom. The opposite rounded
edge at the bottom of the output side allows you to tilt the unit upward to lift it
from the rail while prying the spring clip back with a screwdriver. To attach the
module to T-type DIN rail, angle the top of the unit towards the rail and place the
top groove of the module over the upper lip of the DIN rail. Firmly push the unit
downward towards the rail until it snaps into place. To remove it from the DIN rail,
first separate the input terminal blocks from the bottom side of the module to
create a clearance to the DIN mounting area. You can use a screwdriver to pry the
pluggable terminals out of their sockets. Next, while holding the module in place
from above, insert a screwdriver into the lower path of the bottom of the module to
the DIN rail clip and use it as a lever to force the DIN rail spring clip down while
pulling the bottom of the module outward until it disengages from the rail. Then
simply lift it from the rail.
99.0
(3.90)
114.5
(4.51)
12.5
(0.50)
DIMENSIONS ARE IN MILLIMETERS (INCHES)

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 6 - http://www.acromag.com
- 6 -
http://www.acromag.com
ELECTRICAL CONNECTIONS
WARNING –EXPLOSION HAZARD –Do not disconnect equipment unless power has
been removed or the area is known to be non-hazardous.
WARNING –EXPLOSION HAZARD –Substitution of any components may impair
suitability for Class I, Division 2.
WARNING –EXPLOSION HAZARD –The area must be known to be non-hazardous
before servicing/replacing the unit and before installing.
Wire terminals can accommodate 14-26 AWG solid or stranded wire. Input wiring
may be shielded or unshielded type. Ideally, output wires should be twisted pair.
Terminals are pluggable and can be removed from their sockets by prying outward
from the top with a screwdriver blade. Strip back wire insulation 0.25-inch on each
lead and insert the wire ends into the cage clamp connector of the terminal block.
Use a screwdriver to tighten the screw by turning it in a clockwise direction to
secure the wire (0.5-0.6Nm torque). Since common mode voltages can exist on
signal wiring, adequate wire insulation should be used and proper wiring practices
followed. As a rule, output wires are normally separated from input wiring for
safety, as well as for low noise pickup.
T-Rail
35mm DIN Rail
SCREWDRIVER SLOT
FOR REMOVAL FROM
"T" TYPE DIN RAIL
TILT MODULE UPWARD TOWARDS RAIL
AND HOOK ONTO UPPER LIP OF RAIL.
ROTATE MODULE DOWNWARD TO
ENGAGE SPRING CLIP ONTO LOWER
LIP OF RAIL.
TOP
BOTTOM
(INPUT SIDE)
(OUTPUT SIDE)
TT2XX MODULE DIN RAIL MOUNTING AND REMOVAL
SPRING CLIP
USE SCREWDRIVER TO REMOVE
MODULE FROM RAIL AS SHOWN
TT2XX MODULE
!

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 7 - http://www.acromag.com
- 7 -
http://www.acromag.com
Sensor Input Connections
Sensor wires are wired directly to transmitter input terminals at the bottom of the
module, or the left side (the spring-loaded DIN clip side), as shown in the
connection drawing below. Observe proper polarity when making input
connections.
Use Insulated or Non-Grounded Sensors Only - Input is non-isolated. Do not
ground any input leads.
Two-Wire Input Sensors Require Jumper - For a 2-wire sensor, you must
connect a short copper jumper wire between input terminals 3 and 4 at the
transmitter (see below). Alternately, if you want to compensate for sensor lead
wire resistance, do not include this jumper but add a third copper lead from the
sensor to terminal 4, as shown in the 3-wire connection figure below.
Four-Wire Input Sensors Use 3-Wire Lead Compensation.
INPUT
TERMINALS
+H
-L
INPUT SIDE OUTPUT SIDE
MODEL TT231-0600
TB1
TB2
BOTTOM VIEW
(INPUT SIDE)
DIN RAIL SPRING CLIP
21
43
DIN RAIL SPRING CLIP
IN+
IN-
2
1
3
4
(NC)
2-WIRE3-WIRE
4-WIRE
(2-WIRE ONLY)
ADD JUMPER
PLATINUM RTD OR RESISTANCE
MODEL TT231-0600 INPUT SENSOR WIRING
SHIELDED CABLE
OPT SHIELD GROUND
DO NOT GROUND INPUT LEADS
INPUT
TERMINALS
L
H
+
-
TB1
TB2
(INPUT IS NOT ISOLATED)
FRONT

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 8 - http://www.acromag.com
- 8 -
http://www.acromag.com
Output/Power Connections
This transmitter has an ANSI/ISA Type 2 output in which the unit’s power and
output signal share the same two leads, and the transmitter output has a floating
connection with respect to earth ground. Connect a DC power supply and load in
series in the two-wire loop as shown in drawing below.
Output connections are not polarized. The output + and –designations are for
reference only with current normally input to Output+ and returned via Output-
(current sinking).
Loop supply voltage should be from 9-32V DC with the minimum voltage level
adjusted to supply over-range current to the load, plus 9V minimum across the
transmitter, plus any transmission line drop.
Variations in power supply voltage between the minimum required and 32V
maximum, has negligible effect on transmitter accuracy.
Variations in load resistance has negligible effect on output accuracy, as long as
the loop supply voltage is set accordingly.
Note the traditional placement of earth ground in the current loop. The
transmitter output floats off this ground by the voltage drop in the load
resistance and lead-wire. This is very important when making USB Connections
and will drive the need for USB isolation (see USB Connections section).
Always connect the output/power wires and apply loop power before
connecting the unit to USB.
The traditional loop-powered “sinking” output connections are shown above.
Shielded twisted-pair wiring is often used at the output to connect the longest
distance between the field transmitter and the remote receiver as shown. The
output of this transmitter fluctuates relative to earth ground by the voltage drop in
the load and connection wire. This makes it flexible in the way it connects to
various “Receiver” devices.
INPUT SIDE OUTPUT SIDE
MODEL TT231-0600
MODEL TT231-0600 OUTPUT/POWER WIRING
+-
CC
TB3
TB4
TOP VIEW
(OUTPUT SIDE)
65
87
TRADITIONAL LOOP-POWERED "SINKING OUTPUT" CONNECTIONS
+
-
+
IDC SUPPLY
(9-32V)
+
-
EARTH
GROUND
I
I
RLOAD
-
THIS TRANSMITTER IS CURRENT LOOP POWERED
4-20mA
NOTE: OUTPUT TERMINALS ARE NOT POLARIZED AND
PLUS & MINUS LABELS ARE FOR REFERENCE ONLY.
OPTIONAL WIRING TERMINALS C ARE HELD IN
COMMON AND USED FOR "SOURCING" LOOP WIRING.
SEE OPTIONAL OUTPUT WIRING DIAGRAM.
+
-
6
5
TWISTED PAIR
SHIELDED
OUTPUT
TERMINALS
(UPPER LEVEL)
OPT "C" TERMINALS
(SEE OPT TB4 WIRING)
ARE COMMON
7 8
TB3

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 9 - http://www.acromag.com
- 9 -
http://www.acromag.com
Output/Power
Connections…
In most installations, the loop power supply will be local to either the transmitter,
or local to the remote receiver. Common receiver devices include the input channel
of a Programmable Logic Controller (PLC), a Distributed Control System (DCS), or a
panel meter. Some receivers already provide excitation for the transmitter loop
and these are referred to as “sourcing inputs”. Other receivers that do not provide
the excitation are referred to as “sinking” inputs, and these will require that a
separate power supply connect within the loop. These types of receivers are
depicted below:
WARNING: For compliance to applicable safety and performance standards,
the use of twisted pair output wiring is recommended. Failure to adhere to
sound wiring and grounding practices as instructed may compromise safety,
performance, and possibly damage the unit.
TIP - Ripple & Noise: Power supply ripple at 60Hz/120Hz is normally reduced at the
load by the transmitter, but additional filtering at the load can reduce this ripple
further. For large 60Hz supply ripple, connect an external 1uF or larger capacitor
directly across the load to reduce excessive ripple. For sensitive applications with
high-speed acquisition at the load, high frequency noise may be reduced
significantly by placing a 0.1uF capacitor directly across the load, as close to the load
as possible.
TIP - Inductive Loads: If the two-wire current loop includes a highly inductive load
(such as an I/P current-to-pressure transducer), this may reduce output stability. In
this case, place a 0.1uF capacitor directly across the inductive load and this will
typically cure the problem.
INPUT SIDE OUTPUT SIDE
MODEL TT231-0600
MODEL TT231-0600 OUTPUT WIRING
OUTPUT
TERMINALS
+-
COMMON CC
TB3
TB4
TOP VIEW
(OUTPUT SIDE)
+
-
6
5
65
87
"SINKING OUTPUT" CONNECTIONS WITH
LOOP+
LOOP-
TB4
TB3 +
-
TWISTED PAIR
TERMINALS
I
I
POWER LOCAL TO THE RECEIVER
The 24V DC Excitation is
Provided by the Card
+
RCV
DCS/PLC SINKING
24VDC
Two-Wire Output Connections to the Input Card of a Distributed Control
System or Programmable Logic Controller.
+
-
24VDC POWER SUPPLY
I
I
COMMON TWO-WIRE TRANSMITTER CONNECTION TO "SOURCING" AND "SINKING" INPUT RECEIVERS
+
-
INPUT CARD
-
+RCV
+
-
P
DCS/PLC SOURCING
24VDC
INPUT CARD
+
-
OR
SOURCING INPUT RECEIVER SINKING INPUT RECEIVER
The 24V DC Excitation is Provided
by a Separate Power Supply

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 10 - http://www.acromag.com
- 10 -
http://www.acromag.com
Output/Power
Connections…
This model includes two extra terminal connections at TB4 marked “C” which
provide a convenient wiring point for a “sourcing” wiring variation as shown
below. Internally, these two terminals are connected in common with each
other and do not connect to the internal circuit. Use of these terminals in
your wiring scheme allows you to connect external power local to the
transmitter and form a “sourcing” entity from this “sinking” output as shown.
Earth Ground Connections
The unit housing is plastic and does not require an earth ground connection. If the
transmitter is mounted in a metal housing, a ground wire connection is typically
required and you should connect that metal enclosure’s ground terminal (green
screw) to earth ground using suitable wire per applicable codes. See the Electrical
Connections Drawing for Output/Power and note the traditional position of earth
ground for the two-wire output current loop. The Type II transmitter output
terminals have a floating connection relative to earth ground. Earth ground is
normally applied at the output loop power minus terminal and in common with the
loop load or loop receiver minus.
Do not earth ground any input lead and use only insulated/non-grounded RTD
sensors. This transmitter does not isolate its input signal.
Respect the traditional position of earth ground in a two-wire current loop and
avoid inadvertent connections to earth ground at other points, which would
drive ground loops and negatively affect operation. This includes a USB
connection to the transmitter, which should be made via a USB isolator, as
most Personal Computers earth ground their USB ports and this makes contact
with both the USB signal and shield grounds.
INPUT SIDE OUTPUT SIDE
MODEL TT231-0600
MODEL TT231-0600 OPTIONAL OUTPUT WIRING
OUTPUT
TERMINALS
+-
COMMON CC
TB3
TB4
TOP VIEW
(OUTPUT SIDE)
+
-
6
5
65
7
8
87
OPTIONAL "SOURCING OUTPUT" CONNECTIONS WITH
LOCAL EXTERNAL 3-WIRE POWER FORM
A SOURCING OUTPUT RELATIVE TO THE
LOOP+
LOOP-
OPTIONAL COMMON CONNECTIONS WITH
TB4
TB3
+
24VDC +
-
LOCAL 24VDC
-
POWER SUPPLY
R
I
+
-LOAD
REMOTE RECEIVER/LOAD
+
-
TWISTED PAIR
C
C
TERMINALS
I
I
I
I
I
I
POWER LOCAL TO TRANSMITTER
REMOTE SINKING LOAD.

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 11 - http://www.acromag.com
- 11 -
http://www.acromag.com
USB Connections
This transmitter is setup, configured, & calibrated via configuration software that
runs on a Windows-based PC connected to the unit via USB (Windows XP or later
required). Refer to the following drawing to connect your PC or laptop to the
transmitter for the purpose of reconfiguration and calibration using this software.
WARNING: The intent of mating
USB with this transmitter is so that
it can be conveniently setup and
calibrated in a safe area, then
installed in the field which may be
in a hazardous area. Do not
attempt to connect a PC or laptop
to this unit while installed in a
hazardous area, as USB energy
levels could ignite explosive gases
or particles in the air.
USB Signal Isolation is Required (See Below) - You may use Acromag model
USB-ISOLATOR to isolate your USB port, or you can optionally use another USB
signal isolator that supports USB Full Speed operation (12Mbps).
Configuration Requires USB and Loop Power - This transmitter draws power
from both the current loop, and from USB during setup.
Connect Loop Power Before USB - Always connect the transmitter to its loop
power supply before connecting USB, or erratic operation may result.
IMPORTANT: All USB logic signals to the transmitter are referenced to the potential
of its internal signal ground. This ground is also held in common with the USB
ground and shield ground. The potential of the transmitter’s current output pin
(output minus) relative to earth ground will vary according to the load current and
load resistance (net IR drop). Without isolation, this IR drop would drive a potential
difference between the normally grounded current loop and the grounded USB
connection at the PC, causing a ground loop that would inhibit setup and
calibration, and may even damage the transmitter. This is why an isolated USB
connection is recommended. Alternatively, you could avoid the use of an isolator if
a battery powered laptop was used to connect to the transmitter, and the laptop
has no earth ground connection, either directly or via a connected peripheral.
PERSONAL COMPUTER
RUNNING WINDOWS OS
1 METER CABLE
USB-A MALE
TO HOST USB PORT
HOST
USB
HOST USB SERIAL
PORT CONNECTOR
AT BACK OF PC
CONFIGURATION
SOFTWARE
ACROMAG
HOST PC RUNNING
USB-B MALE
DEVICE
CONNECT
PC
CONNECT
POWER RESET
CONNECTION
Acromag
THE LEADER IN INDUSTRIAL I/O
R
USB-A MALE
USB-ISOLATOR
USB MiniB Socket
(Front-Panel of Module)
MODEL TT2XX TRANSMITTER
USB MiniB MALE
TT SERIES USB TRANSMITTER CONNECTIONS
LED
(RECOMMENDED)
USED FOR CONFIGURATION AND CALIBRATION OF THE TRANSMITTER IN A SAFE OR ORDINARY LOCATION
CABLE Model 4001-113
MODEL NO. - USB-ISOLATOR
CABLE Model 4001-112
Refer to Configuration Software Kit, Model TTC-SIP, which includes:
1 ea, Model 4001-113 USB Cable
1 ea, Model 4001-112 USB Cable
1 ea, Model USB-ISOLATOR
1 ea, Model TT-CONFIG CDROM Software
!
Note: Output/Power to Transmitter must
be applied before USB connection
(See Output/Power Connections).

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 12 - http://www.acromag.com
- 12 -
http://www.acromag.com
CONFIGURATION SOFTWARE
Quick Overview
This transmitter can only be
configured and calibrated via its
Configuration Software and a USB
connection to your PC or laptop.
The configuration software can be
downloaded free of charge from
our web site www.acromag.com.
This software is also included on a
CDROM bundled with the
Configuration Kit TTC-SIP (see
Accessories section). For this
model, look for program
TT231Config.exe. The software is
compatible with XP or later
versions of the Windows operating
system.
The configuration software screen
for this model is shown at right.
The configuration screen is divided
into six sections as follows: Device
Connect, Configuration &
Calibration, Under/Over Scale
Thresholds, Sensor Fault/Break
Detection, Factory Settings, Unit
Status, and the System Message
Bar at the bottom of the screen. A
short description of each of these
groups follows.
For detailed configuration and
calibration procedures, see the
Operation Step-By-Step section of
the Technical Reference on page
14 of this manual.
Device Connect (First Connect to Unit Here)
Scan for connected transmitters and open communications with them.
Display the model/serial number (Product Name), Manufacturer, and Serial
Number of the connected transmitter.
This section is used to scan for connected transmitters, select a connected
transmitter, open communications with it, and close connections with it. Device
connection Status is also indicated here, along with the connected transmitter’s ID
info (Product Name/serial, Manufacturer, & Serial Number).
Configuration / Calibration (Next Configure Unit Then Calibrate I/O)
Optional - Read the unit’s current configuration with “Get Config” button.
Set the Input Type, Platinum RTD or Resistance.
Set the input wiring to Two-wire or Three/Four-wire sensor connections.
Set the alpha coefficient of your particular RTD curve.
Set the RTD Temperature Units.
Set the input range zero and full-scale temperature or resistance.
Set the output range zero and full-scale (usually 4mA and 20mA).
Last, after making changes, calibrate your settings for zero, gain, excitation, and
linearization by clicking “Start Calibration” and follow the on-screen prompts.
Use these controls to configure the channel, then calibrate your I/O selection. You
must calibrate any changes you make in this section by clicking Start Calibration
after making your selections.

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 13 - http://www.acromag.com
- 13 -
http://www.acromag.com
Quick Overview…
HELP –You can press F1 for Help
on a selected or highlighted field
or control. You can also click the
[?] button in the upper-right hand
corner of the screen and then click
to point to a field or control to get
a Help message pertaining to the
item you pointed to.
For detailed configuration and
calibration procedures, see the
Operation Step-By-Step section of
the Technical Reference on page
14 of this manual.
The Configuration/Calibration section includes a type field where you are prompted
to enter measured current values for zero and full-scale after starting calibration.
You can also read the current transmitter configuration with “Get Config”, or
“Abort” calibration if necessary.
Under/Over Scale Thresholds (Sets Output Range & Alarm Levels)
Select the output under-scale and over-scale thresholds to define your linear
output operating range.
Indirectly sets the upscale and downscale fault limits outside of your linear
operating range to 1mA above over-scale, and 0.4mA below the under-scale
threshold settings.
Use these controls to define the linear operating range of the output, and its
associated alarm limits. Once you have made your selections, you can click the
“Submit U/O Configuration” button to engage your settings.
Break Detection (Sets Direction of Output Upon Fault)
Select output Downscale or Upscale lead-break or sensor fault detection.
Use these controls to set the direction that the output should go if a sensor lead
breaks. Then click the “Submit Break Detection” button to write your selection to
transmitter memory. Then a lead break or sensor burnout fault will send the output
to the upper or lower alarm level, according to this setting. Alarm levels are set
outside of the linear output operating range to 1mA above the over-scale threshold,
or 0.4mA below the under-scale threshold.
Factory Settings (In Case of Trouble)
Restores a transmitter to its original factory calibration.
Restores a transmitter to its initial factory configuration.
You can click the “Restore Factory Settings” button if you ever misconfigure or
miscalibrate a transmitter in such a way that its operation appears erratic.
Unit Status (For Validation & Trouble-Shooting)
Tests the integrity of your USB connection to the transmitter.
Reads the Fault Status of your input signals with respect to input amp.
Resets the transmitter (sets it to its power-up configuration).
Use the “Read Status” control to test communication and obtain diagnostic
information relative to the input. Input Fault Status messages will be returned on
the “Fault Status:” line, and in the system message bar at the bottom of the screen.
Optionally use the “Reset Unit” control to revert to the power-up or stored
configuration, or to clear a checksum error. Refer to Read Status of the Operation
Step-by-Step section for more information.
Message Bar (Bottom of Screen)
Displays the Fault Status message of your input signal (see above).
Displays other prompt instructions during calibration.
The system message bar at the bottom of the screen will display & repeat prompt
instructions as you step through calibration. It also displays diagnostic messages
after clicking “Read Status”.

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 14 - http://www.acromag.com
- 14 -
http://www.acromag.com
TECHNICAL REFERENCE
OPERATION STEP-BY-STEP
Connections
This section will walk you through
the Connection-Configuration-
Calibration process step-by-step.
But before you attempt to
reconfigure or recalibrate this
transmitter, please make the
following electrical connections
Note: Your input source and output meter must be accurate beyond the unit
specifications, or better than ±0.1%. A good rule of thumb is that your equipment
source accuracy should be four times better than the rated accuracy you are trying
to achieve with this transmitter.
1. Connect Input: Refer to Sensor Input Connections of page 7 and connect a
precision resistance decade box or RTD calibrator to the input, as required.
Your resistance source must be adjustable over the range desired for zero and
full-scale. A 3-wire or 4-wire sensor connection is recommended, as this will
compensate for sensor lead resistance (this unit will use 3-wire lead
compensation for 4-wire sensors). Be sure to either wire a third lead to the
remote sensor, or install a short copper jump-wire between input terminals 3
& 4 of the transmitter, as this serves as the return path for the excitation
current and must be present for operation.
2. Connect Output/Power: Refer to Output/Power Connections of pages 7-9 and
wire an output current loop to the transmitter as illustrated. You will need to
measure the output current accurately in order to calibrate the unit. You could
connect a current meter in series in this loop to read the loop current directly
(not recommended). Alternatively, you could simply connect a voltmeter
across a series connected precision load resistor in the loop, then accurately
read the output current as a function of the IR voltage drop produced in this
resistor (recommended). In any case, be sure to power the loop with a voltage
that minimally must be greater than the 9V required by the transmitter, plus
the IR drop of the wiring and terminals, plus the IR drop in the load. To
compute the IR drop, be sure to use a current level that considers the over-
scale current and alarm limit by adding 1mA to the over-scale threshold that
you select (this could be as high as 30mA depending on your selection of over-
scale threshold).
Loop Power Supply Voltage: Make sure your voltage level is at least 9V plus
0.020*load_resistance. Ideally, it should be great enough to drive the over-
range alarm current into your load (i.e. up to 9V+ 0.030*Rload, assuming line
drop is negligible and the maximum possible over-range threshold is
configured). The non-volatile memory of the transmitter receives its power
from the loop supply, not USB. Therefore, apply power to the transmitter
output loop and always power the loop before connecting to USB.
3. Connect to PC via USB: Refer to USB Connections of page 11 and connect the
transmitter to the PC using the USB isolator and cables provided in
Configuration Kit TTC-SIP.
Now that you have made your connections and applied power, you can
execute the TT231Config.exe software to begin configuration of your unit
(software is compatible with XP or later versions of the Windows operating
system).
Connect Input
Connect Output
Connect PC/USB
Configure
Calibrate I/O

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 15 - http://www.acromag.com
- 15 -
http://www.acromag.com
Configuration
Note that without a device already
connected via USB, the Device
Status field indicates
“Disconnected”.
After you connect USB, the first
step to begin Configuration is to
select the device to connect to
using the scroll window of the
Device Name field. Use the scroll
bar to click on and select a
transmitter from this list in order
to open it for reconfiguration (use
the serial number to discern a
particular transmitter). Then click
the “Open” button to connect to
the selected device.
If your transmitter was already
connected via USB when you
booted this software, your screen
will look more like the screen at
right, where the software has
already initiated a connection to
the transmitter for you (see Device
Connect area and note that Device
Status indicates “Connected”).
Note that the software
automatically opened the
connection with the transmitter
and “Read Complete” is indicated
in the message bar at the bottom
of the screen. Additionally, most
fields and controls are not faded
out and await your input.
After executing the Acromag Configuration software for this model, a screen similar
to the following will appear if you have not already connected to your transmitter
via USB (note some fields are faded out under these conditions):

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 16 - http://www.acromag.com
- 16 -
http://www.acromag.com
Configuration…
HELP –You can press F1 for Help
on a selected or highlighted field
or control. You can also click the
[?] button in the upper-right hand
corner of the screen and click to
point to a field or control to get a
Help message pertaining to the
item you pointed to.
If more than one transmitter is connected via USB through a USB hub, the software
automatically opens a connection with one of the transmitters and “Read
Complete” is indicated in the message bar at the bottom of the screen. You can
discern which transmitter is open by referring to the product’s unique serial number
indicated next to the Product Name. If your intent was to open a different hub
transmitter, you will have to “Close” the current connection and use the Device
Name scroll bar to select another unit (discern unit by serial number). Then click
“Open” to communicate with it. If you break the USB connection to a transmitter,
the software will automatically close the connection for you. When you reconnect
the cable, you will have to click “Open” to reopen communication with the
transmitter.
Open the Transmitter for Communication….
Once you have opened a transmitter for communication, the device status will
change from “Ready” to “Connected”, and the transmitter ID information will be
displayed in the Product Name, Manufacturer, and Serial Number fields. At this
point, the connected transmitter is ready for configuration and the appropriate
configuration fields become active and await your input.
If you want to see how the connected unit is already configured before changing its
configuration, click the “Get Config” button of the Configuration & Calibration
controls to retrieve its current configuration information. Note the message bar at
the bottom of the screen and it should display a message like “Read Complete!
Normal Operation, inputs in range”
IMPORTANT: If you make any changes to the Configuration Parameters, you will
have to recalibrate the unit via the “Start Calibration” button in order to actually
write those changes to the transmitter.
Select the Input Type…
In the Calibration section of this screen, select an input type: Platinum RTD, or
Resistance.
If you select “Platinum RTD”, your output will be linear with respect to sensor
temperature, not resistance, and you will additionally have to use the “Alpha
Value” scroll window to select your particular RTD curve type (alpha is only
used by the software to recommend resistance values during calibration).
If you select “Resistance”, your output current will be linear with respect to
sensor resistance, not temperature, and no special linearization will be
performed.
Note that you must already have loop power connected to the transmitter
before you execute this software. If you do not, the software will prompt you
to make this connection when you execute the software program. If you later
interrupt loop power while already using the software and while connected to
USB, you may have to re-open communication with the unit.

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 17 - http://www.acromag.com
- 17 -
http://www.acromag.com
Configuration…
HELP –You can press F1 for Help
on a selected or highlighted field
or control. You can also click the
[?] button in the upper-right hand
corner of the screen and click to
point to a field or control to get a
Help message pertaining to the
item you pointed to.
Select the Sensor Wiring…
This selection tells the unit which inputs to connect to its internal PGA, and which
inputs to connect its excitation sources to.
If you select “Two-Wire”, your input measurement will not be compensated for
the sensor lead resistance, and your input range zero will be fixed at 0°C (Pt
RTD). Sensor leads less than a few feet long will have negligible resistance,
minimizing the importance of lead-wire compensation in these applications.
If you select “Three-Wire”, your input measurement will be compensated for
its lead-wire resistance, as long as the ± input leads are of the same length, size,
and type. Additionally, you will be able to select an input zero of -50°C, 0°C, or
0°F (input zero is a fixed selection of 3 different values, while the full-scale is
programmable to any value in range). If you have a four-wire sensor, select
“Three-Wire”.
A selection of “Two Wire” requires that you additionally wire input terminals 3
& 4 together with a short copper jumper wire. A selection of “Three Wire”
requires that a third lead be wired to input terminal 4 and the other end of this
lead connects to the minus terminal at the sensor. In both cases, this “third-
wire” connection serves as the return path for the excitation current and it must
be present in either form, in order to make your measurement. If you have
actually wired a four-wire sensor, it will use 3-wire lead compensation.
Select the Alpha Value…
(Pt RTD Only, for internal use only)
For the Pt RTD Input Type, you should specify the Alpha Value of your particular
RTD curve. The software only uses this information to compute the input
resistances required to calibrate your selected input range for Platinum RTD Input
Types, which it then returns in message prompts during the calibration process. If
you are calibrating to a particular curve not indicated, you may select this value
arbitrarily and just substitute your own resistance values during calibration that will
correspond to your particular curve at the temperatures noted.
Note: 1Alpha (  ) is used to identify the RTD curve and its value is derived by dividing
the sensor resistance at 100  C (boiling point of water) minus the sensor resistance at
0ºC (freezing point of water), by the sensor resistance at 0  C, then by 100  C (  =
[R100
 C -R0  C] / R0  C/ 100
 C). For Pt 100  , this is 38.5  /100.0  /100  C, or
0.00385  /  /  C, and represents the average change in resistance per ºC.
Select the Temperature Units…
(Pt RTD Only)
For your input range, select the temperature units in degrees Celsius or degrees
Fahrenheit. Note that input ranges specified in degrees Fahrenheit will have a fixed
input range zero of 0°F. Units in °C can chose an input range zero of -50°C or 0°C.

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 18 - http://www.acromag.com
- 18 -
http://www.acromag.com
Configuration…
HELP –You can press F1 for Help
on a selected or highlighted field
or control. You can also click the
[?] button in the upper-right hand
corner of the screen and click to
point to a field or control to get a
Help message pertaining to the
item you pointed to.
Select the Input Range Zero and Input Range Full-Scale…
Next you need to select the input temperature range for the Pt RTD Input Type, or
your input resistance range for the Resistance Input Type.
Your selection of Input Zero is the RTD temperature or input resistance that will
correspond to 0% of output. For Platinum RTD types, use the scroll bar to select
your Input Zero temperature: -50°C, 0°C, or 0°F (Zero is a fixed value for Pt RTD).
For Resistance Input Type, you instead enter an Input Zero value in ohms (0Ω
typical, for a 0-500Ω range, or 100Ω typical for a 100-200Ω range). If you choose 0Ω
as your input zero, then your under-scale threshold selection set in a later step
cannot be achieved, except for the purpose of indirectly setting the downscale
alarm limit, which is ~0.4mA below your under-scale threshold setting.
Note that when setting your range, some under-range is built-in later via the Under-
scale Threshold selection set separately (see below).
Note that this selection indirectly determines the PGA minus lead connection from
the input multiplexer. Different paths are chosen which have different pedestal
resistors installed that happen to be set just below the corresponding resistance of
the platinum input sensor at its zero temperature. For example, the Resistance Input
Type will use the 0°C pedestal resistor which is 98.8Ω. An equivalent sensor input
resistance actually drives the differential signal measurement to 0V.
Next, enter your Input Full-Scale temperature (Pt RTD Input), or full-scale resistance
(Resistance Input Type). Your Input Full-Scale selection will correspond to 100% of
output. For Pt RTD, you can enter any value up to 850°C. For the Resistance input
type, you can enter any resistance value up to 900Ω. Note that the unit does
convert under-range and over-range values outside of the 0% and 100% limits, and
this is set by separately selecting the output Under/Over-scale Thresholds.
Not all combinations of Input Zero and Input Full-Scale will be possible. The
software may prompt you to make another selection. Also, if the input zero and full-
scale points are chosen too close together, performance will be degraded. A
minimum span of 50°C is recommended. Note that you will have to be able to
precisely drive the corresponding input range resistance values for zero and full-
scale in order to calibrate your input range later.
Select the Output Range Zero and Output Range Full-Scale…
In the Output Zero and Output Full-Scale fields, enter the output currents that are
to correspond to 0% and 100% of output respectively. This is typically 4mA and
20mA, respectively, but you could optionally specify an output zero from 3.5mA up
to 6.0mA, or an output full-scale from 16mA up to 24mA. Note that the output
range over-scale and under-scale thresholds are specified separately and will
determine the linear operating range of the output including possible over/under-
range outside of these approximate limits.
If the output zero and full-scale points are chosen too close together, performance
will be degraded. Use input spans greater than 50°C.

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 19 - http://www.acromag.com
- 19 -
http://www.acromag.com
Configuration…
HELP –You can press F1 for Help
on a selected or highlighted field
or control. You can also click the
[?] button in the upper-right hand
corner of the screen and click to
point to a field or control to get a
Help message pertaining to the
item you pointed to.
The actual operating range limits of your input sensor will depend on the linear
output operating range defined by the output under-scale and over-scale threshold
limit settings (set separately below). Threshold limiting allows you to define an
under-scale threshold, typically between 2.1mA and 3.6mA, and an over-scale
threshold between 21mA and 30mA. This indirectly corresponds to a linear
operating range outside of the input zero and full-scale limits. It also indirectly
defines the fault current levels which will be ~0.4mA below the under-scale
threshold for down-scale detection, and ~1.0mA above the over-scale threshold for
upscale detection. The Min/Max range of adjustment has already been calibrated
at the factory and the Min/Max values indicated will vary between units. Note that
the range of adjustment for the threshold levels can vary as much as ±10% of span
between units for the same “digital” setting.
Calibrate I/O Range Selection
CAUTION: RTD Input levels
outside of the nominal input range
of the unit
(-50° to +850°C, or 0-900Ω) will not
be accepted for configuration of
zero or full-scale. Since not all
input levels can be validated
during field programming,
connecting or entering incorrect
signals will produce an undesired
output response.
IMPORTANT: If you make any changes to the Configuration parameters, you must
re-calibrate your input. Any changes to the Input Type, Sensor Wiring, Input
Zero/Full-Scale, or Output Zero/Full-Scale, are not written to the transmitter until
you complete the calibration sequence that is initiated by clicking the “Start
Calibration” button.
You can use the “Get Config” Calibration control button to read the current
configuration of the unit if you like, perhaps to determine the active configuration
prior to recalibrating it. Note that it will over-write the configuration parameter
selections of this screen that you may have just changed. It a good idea to always
check the current configuration selections to affirm your intentions before clicking
“Start Calibration”.
After making your input type and I/O range selections, you can click the “Start
Calibration”button of the Calibration section to begin calibrating your selections.
Calibration is a simple two step process (Resistance Input), or three step process (Pt
RTD Input), that adjusts the I/O range zero, the PGA gain and excitation, and
linearization (Pt RTD only). If you make a mistake and need to repeat a step, just
click “Abort Calibration” to restart from the beginning.
Calibration is an interactive process in which the software prompts you to apply
input signals and then measure the corresponding output current. First, it will
prompt you to apply the zero input signal resistance, then measure and record the
corresponding zero output signal current. Second, it does the same for the full-
scale input resistance and the corresponding full-scale output current signal (it
makes adjustments to gain at this stage, but with linearization turned off). Third for
Pt RTD input types, it enables linearization and prompts you to apply the full-scale
input resistance signal again and then measure and record the corresponding full-
scale output current (it uses this second full-scale measurement to adjust the
magnitude of its linearization correction for the sensor). There may still be
combinations of zero and full-scale that you will not be able to adjust and calibrate
the unit for. For example, this might occur for very tight input spans, or odd
endpoints. The Configuration Software will usually let you know when you need to
adjust your desired limits as you enter them.

Model TT231-0600
Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: [phone]
- 20 - http://www.acromag.com
- 20 -
http://www.acromag.com
Zero, Full-Scale, & Linearizer Calibration Procedure
By default, the unit is factory calibrated to a 100Ω, Pt385 RTD type, using a 3-wire
sensor connection, and a 0° to 200°C input span to drive a 4mA to 20mA output
span. For our example below, we will instead use the 0 to 500C portion of the Pt
RTD type to drive a 4 to 20mA output range.
Zero, Full-Scale, & Linearizer Calibration Procedure
1. After configuring your input type and I/O ranges, you can begin calibrating the
transmitter by clicking the “Start Calibration” button and the following message
will appear:
Your unit needs to calibrate its zero signal. The software used your input type
and alpha information to compute the equivalent RTD resistance of the input
zero value you specified, and returned that value in this prompt. Click OK and
this message is repeated in the system message window at the bottom of the
screen. Adjust your input signal to the zero input value noted. Because this
input is a Pt 100Ω sensor, and 0°C is our input zero, our input signal should be
precisely set to 100.00 ohms. Measure the corresponding output current and
type the measured current in milliamps into the Measured Current Output
field. Then click the “Go To Step 2” button.
2. After clicking “Go To Step 2”, the following message will be displayed:
Now the unit needs to calibrate its gain to produce your full-scale endpoint.
The software used your input type and alpha information to compute the
equivalent RTD resistance of the input full-scale value you specified, and
returned that value in this prompt. Click OK and this message is repeated in the
system message window at the bottom of the screen. You need to adjust your
input signal to the full-scale input value noted. Measure the corresponding
output current accurately and type the measured output current in milliamps
into the Measured Current Output field. Then click the “Go To Step 3” button
(only Pt RTD inputs will require a 3rd step).
Note that at this point, your output signal will not be an accurate full-scale
output (RTD Input), as linearization is OFF and calibration has not been
completed. The second step only sets the gain of the PGA amplifier to drive the
full-scale output, but without RTD linearization turned on.
If your Input Type is Resistance, your calibration is complete after this step
because no special linearization correction applies (your output is already linear
with resistance). You simply need to click the Complete Calibration button to
continue and your resistance transmitter should be calibrated.