Measurement Computing Measurement Advantage USB-TC User manual

USB-TC
Measurement Advantage™ brand
USB-based 8-Channel Thermocouple
Input Module
User's Guide
Document Revision 2, March, 2005
© Copyright 2005, Measurement Computing Corporation

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USB-TC User's Guide
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iii
Table of Contents
Preface
About this User’s Guide .......................................................................................................................v
What you will learn from this user’s guide.........................................................................................................v
Conventions in this user’s guide.........................................................................................................................v
Where to find more information .........................................................................................................................v
Chapter 1
Introducing the USB-TC ................................................................................................................... 1-1
Overview: USB-TC features........................................................................................................................... 1-1
USB-TC block diagram .................................................................................................................................. 1-2
Software features ............................................................................................................................................ 1-2
Connecting a USB-TC to your computer is easy............................................................................................ 1-3
Chapter 2
Installing the USB-TC ....................................................................................................................... 2-1
What comes with your USB-TC shipment?.................................................................................................... 2-1
Hardware ....................................................................................................................................................................... 2-1
Software......................................................................................................................................................................... 2-1
Documentation............................................................................................................................................................... 2-2
Unpacking the USB-TC.................................................................................................................................. 2-2
Installing the software .................................................................................................................................... 2-2
Installing the hardware ................................................................................................................................... 2-2
Configuring the USB-TC................................................................................................................................ 2-3
Calibrating the USB-TC ................................................................................................................................. 2-3
Chapter 3
Sensor Connections ......................................................................................................................... 3-1
Screw terminal pin out.................................................................................................................................... 3-1
Thermocouple input terminals (C0H/C0L to C7H/C7L) ............................................................................................... 3-2
Ground terminals (GND) ............................................................................................................................................... 3-2
Power terminals (+5V)................................................................................................................................................... 3-2
Digital terminals (DIO0 to DIO7).................................................................................................................................. 3-2
CJC sensors.................................................................................................................................................................... 3-2
Thermocouple connections............................................................................................................................. 3-3
Wiring configuration...................................................................................................................................................... 3-3
Digital I/O connections................................................................................................................................... 3-3
Chapter 4
Functional Details ............................................................................................................................. 4-1
Thermocouple measurements ......................................................................................................................... 4-1
Cold junction compensation (CJC) ................................................................................................................................ 4-1
Data linearization........................................................................................................................................................... 4-1
Open-thermocouple detection (OTD) ............................................................................................................................ 4-1
USB connector................................................................................................................................................ 4-2
LED ................................................................................................................................................................ 4-2
Power.............................................................................................................................................................. 4-2
Chapter 5
Specifications.................................................................................................................................... 5-1
Analog input section....................................................................................................................................... 5-1
Channel configurations................................................................................................................................... 5-1
Accuracy......................................................................................................................................................... 5-2

USB-TC User's Guide
iv
Thermocouple measurement accuracy ........................................................................................................................... 5-2
Throughput rate .............................................................................................................................................. 5-2
Digital input/output ........................................................................................................................................ 5-3
Memory .......................................................................................................................................................... 5-3
Microcontroller............................................................................................................................................... 5-3
USB +5V voltage ........................................................................................................................................... 5-3
Power.............................................................................................................................................................. 5-4
USB specifications ......................................................................................................................................... 5-4
Environmental ................................................................................................................................................ 5-4
Mechanical ..................................................................................................................................................... 5-4
Screw terminal connector type and pin out .................................................................................................... 5-5
Screw terminal pin out ................................................................................................................................................... 5-5

v
Preface
About this User’s Guide
What you will learn from this user’s guide
This user’s guide explains how to install, configure, and use the USB-TC so that you get the most out of
its USB-based temperature measurement features.
This user’s guide also refers you to related documents available on our web site, and to technical support
resources that can also help you get the most out of these boards.
Conventions in this user’s guide
For more information on …
Text presented in a box signifies additional information and helpful hints related to the subject matter you
are reading.
Caution! Shaded caution statements present information to help you avoid injuring yourself and
others, damaging your hardware, or losing your data.
<#:#> Angle brackets that enclose numbers separated by a colon signify a range of numbers,
such as those assigned to registers, bit settings, etc.
bold text Bold indicates names of objects on the screen, such as buttons, text boxes, and check
boxes. For example:
1. Insert the disk or CD and click the OK button.
italic text Italic text indicates the names of manuals and help topic titles, and to emphasize a
word or phrase. For example:
!The InstaCal®installation procedure is explained in the DAQ Software Quick Start.
!Never touch the exposed pins or circuit connections on the board.
Where to find more information
The following electronic documents provide helpful information relevant to the operation of the USB-TC.
!MCC's Specifications: USB-TC (the PDF version of Chapter 5 in this guide) is available on our web
site at www.mccdaq.com/pdfs/USB-TC.pdf.
!MCC's DAQ Software Quick Start is available on our web site at
www.mccdaq.com/PDFmanuals/DAQ-Software-Quick-Start.pdf.
!MCC's Guide to Signal Connections is available on our web site at
www.mccdaq.com/signals/signals.pdf.
!MCC's Universal Library User's Guide is available on our web site at
www.mccdaq.com/PDFmanuals/sm-ul-user-guide.pdf.
!MCC's Universal Library Function Reference is available on our web site at
www.mccdaq.com/PDFmanuals/sm-ul-functions.pdf.
!MCC's Universal Library for LabVIEW™User’s Guide is available on our web site at
www.mccdaq.com/PDFmanuals/SM-UL-LabVIEW.pdf.
This user's manual is also available on our web site at www.mccdaq.com/PDFmanuals/USB-TC.pdf.

1-1
Chapter 1
Introducing the USB-TC
Overview: USB-TC features
This user's guide contains all of the information you need to connect the USB-TC to your computer and
to the signals you want to measure. The USB-TC is part of the Measurement Advantage™ brand of USB-
based data acquisition products.
The USB-TC is a USB 2.0 full-speed, thermocouple input module that is supported under Microsoft®
Windows®98 (2nd edition), Windows ME, Windows 2000, and Windows XP. The USB-TC is fully
compatible with both USB 1.1 and USB 2.0 ports.
The USB-TC provides eight differential thermocouple input channels. Eight independent, TTL-
compatible digital I/O channels are provided to monitor TTL-level inputs, communicate with external
devices, and to generate alarms. The digital I/O channels are software programmable for input or output.
With the USB-TC, you can take measurements from type J, K, R, S, T, N, E, and B thermocouples.
The USB-TC provides two integrated cold junction compensation (CJC) sensors for thermocouple
measurements.
An open thermocouple detection feature lets you detect a broken thermocouple. An on-board
microprocessor automatically linearizes the measurement data.
The USB-TC is a standalone plug-and-play module which draws power from the USB cable. No external
power supply is required. All configurable options are software programmable.
The USB-TC is fully software calibrated.

USB-TC User's Guide Introducing the USB-TC
1-2
USB-TC block diagram
USB-TC functions are illustrated in the block diagram shown here.
24-bit A/D
(CH0, CH1)
Input
mux.
Input
mux.
CJC
CH0-3
Precision
5V Ref.
24-bit A/D
(CH2, CH3)
24-bit A/D
(CH4, CH5)
Input
mux.
Input
mux.
CJC
CH4-7
24-bit A/D
(CH6, CH7)
Screw terminalScrew terminalScrew terminal
Isolated
Micro
Tem p
sensor
I/O
Isolator
500 V
Isolation
Barrier
USB
Micro
USB
SPI
Isolated
DC/DC
USB
+5V
(+12)
(-12)
8
DIO
Figure 1-1. USB-TC functional block diagram
Software features
The following software ships with the USB-TC free of charge.
!InstaCal installation, calibration, and test utility
!TracerDAQ™ suite of virtual instruments
!SoftWIRE® for Visual Studio® .NET graphical programming
!MCC DAQ Components for VS .NET (installed with SoftWIRE for VS .NET)
For information on the features of InstaCal, TracerDAQ, and SoftWIRE, refer to the DAQ Software
Quick Start booklet that shipped with the USB-TC.

USB-TC User's Guide Introducing the USB-TC
1-3
Connecting a USB-TC to your computer is easy
Installing a data acquisition device has never been easier.
!The USB-TC relies upon the Microsoft Human Interface Device (HID) class drivers. The HID class
drivers ship with every copy of Windows that is designed to work with USB ports. We use the
Microsoft HID because it is a standard, and its performance delivers full control and maximizes data
transfer rates for your USB-TC. No third-party device driver is required.
!The USB-TC is plug-and-play. There are no jumpers to position, DIP switches to set, or interrupts to
configure.
!You can connect the USB-TC before or after you install the software, and without powering down
your computer first. When you connect an HID to your system, your computer automatically detects
it and configures the necessary software. You can connect and power multiple HID peripherals to
your system using a USB hub.
!You can connect your system to various devices using a standard four-wire cable. The USB
connector replaces the serial and parallel port connectors with one standardized plug and port
combination.
!You do not need a separate power supply module. The USB automatically delivers the electrical
power required by each peripheral connected to your system.
!Data can flow two ways between a computer and peripheral over USB connections.

2-1
Chapter 2
Installing the USB-TC
What comes with your USB-TC shipment?
The following items are shipped with the USB-TC.
Hardware
The following items should be included with your shipment.
!USB-TC
!USB cable (2 meter length)
Software
The Measurement Computing Data Acquisition Software CD contains the following software:
!InstaCal installation, calibration, and test utility
!TracerDAQ suite of virtual instruments
!SoftWIRE for VS .NET
!SoftWIRE MCC DAQ Components for .NET
(installed with SoftWIRE for VS .NET)

USB-TC User's Guide Installing the USB-TC
2-2
Documentation
In addition to this hardware user's guide, you should also receive the DAQ Software Quick Start
(available in PDF at www.mccdaq.com/PDFmanuals/DAQ-Software-Quick-Start.pdf). Please read this
booklet completely before installing any software and hardware.
Unpacking the USB-TC
As with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the USB-TC from its packaging, ground yourself using a wrist strap or by
simply touching the computer chassis or other grounded object to eliminate any stored static charge.
If your USB-TC is damaged, notify Measurement Computing Corporation immediately by phone, fax, or
e-mail. For international customers, contact your local distributor where you purchased the USB-TC.
!Phone: [phone] and follow the instructions for reaching Tech Support.
!Fax: [phone] to the attention of Tech Support
!Email: [e-mail]
Installing the software
Refer to the DAQ Software Quick Start for instructions on installing the software on the Measurement
Computing Data Acquisition Software CD. This booklet is available in PDF at
www.mccdaq.com/PDFmanuals/DAQ-Software-Quick-Start.pdf.
Installing the hardware
To connect the USB-TC to your system, turn your computer on, and connect the USB cable to a USB port
on your computer or to an external USB hub that is connected to your computer. The USB cable provides
power and communication to the USB-TC.
When you connect the USB-TC for the first time, a Found New Hardware popup balloon (Windows XP)
or dialog (other Windows versions) opens as the USB-TC is detected.
When this balloon or dialog closes, the installation is complete. The USB LED should flash and then
remain lit. This indicates that communication is established between the USB-TC and your computer.
Caution! Do not disconnect any device from the USB bus while the computer is communicating with
the USB-TC, or you may lose data and/or your ability to communicate with the USB-TC.
If the LED turns off
If the LED is lit but then turns off, the computer has lost communication with the USB-TC. To restore
communication, disconnect the USB cable from the computer, and then reconnect it. This should restore
communication, and the LED should turn back on.

USB-TC User's Guide Installing the USB-TC
2-3
Configuring the USB-TC
All hardware configuration options on the USB-TC are programmable with software. Use InstaCal to set
the thermocouple type for each channel pair. Configuration options are stored on the USB-TC 's isolated
microcontroller in EEPROM, which is non-volatile memory on the USB-TC module. Configuration
options are loaded on power up. The factory default configuration is Type J thermocouple.
Allow the USB-TC to warm up for 30 minutes after powering up before taking measurements. This warm
up time minimizes thermal drift and achieves the specified rated accuracy of measurements.
Calibrating the USB-TC
The USB-TC is fully calibrated via InstaCal. Allow a 30 minute warm up before calibrating.

3-1
Chapter 3
Sensor Connections
The USB-TC supports type types J, K, R, S, T, N, E, and B thermocouples.
Thermocouple selection
The thermocouple type you select will depend on your application needs. Review the temperature ranges
and accuracies of each type to determine which is best suited for your application.
Screw terminal pin out
The USB-TC has four rows of screw terminals — two rows on the top edge of the housing, and two rows
on the bottom edge. Each row has 26 connections. Between each bank of screw terminals are two
integrated CJC sensors used for thermocouple measurements. Signals are identified in Figure 3-1.
RSVD 1 NC 2 C0H 3 C0L 4 NC 5 C1H 7 C1L 8 GND 9 NC 12 C2H 13 C2L 14 NC 15 C3H 17 C3L 18 GND 19 +5V 21 GND 22 DIO0 23 DIO1 24 DIO2 25 DIO3 26
6
10
11
16 20
RSVD RSVD RSVD RSVD RSVD
27 RSVD 28 GND 29 C7L 30 C7H 31 32 NC 33 C6L 34 C6H 35 NC 36 37 38 GND 39 C5L 40 C5H 41 42 NC 43 C4L 44 C4H 45 NC 46 47 +5V 48 GND 49 DIO7 50 DIO6 51 DIO5 52 DIO4
RSVD RSVD RSVD RSVD RSVD
CJC SensorCJC Sensor
Figure 3-1. USB-TC screw terminal pin numbers

USB-TC User's Guide Sensor Connections
3-2
Table 3-1. USB-TC screw terminal descriptions
Pin Signal Name Pin Description Pin Signal Name Pin Description
1 RSVD Reserved, Do Not Use 27 RSVD Reserved, Do Not Use
2 NC Not connected 28 GND Ground
3 C0H CH0 sensor input (+) 29 C7L CH7 sensor input (-)
4 C0L CH0 sensor input (-) 30 C7H CH7 sensor input (+)
5 NC Not connected 31 RSVD Reserved, Do Not Use
6 RSVD Reserved, Do Not Use 32 NC Not connected
7 C1H CH1 sensor input (+) 33 C6L CH6 sensor input (-)
8 C1L CH1 sensor input (-) 34 C6H CH6 sensor input (+)
9 GND Ground 35 NC Not connected
10 RSVD Reserved, Do Not Use 36 RSVD Reserved, Do Not Use
CJC sensor CJC sensor
11 RSVD Reserved, Do Not Use 37 RSVD Reserved, Do Not Use
12 NC Not connected 38 GND Ground
13 C2H CH2 sensor input (+) 39 C5L CH5 sensor input (-)
14 C2L CH2 sensor input (-) 40 C5H CH5 sensor input (+)
15 NC Not connected 41 RSVD Reserved, Do Not Use
16 RSVD Reserved, Do Not Use 42 NC Not connected
17 C3H CH3 sensor input (+) 43 C4L CH4 sensor input (-)
18 C3L CH3 sensor input (-) 44 C4H CH4 sensor input (+)
19 GND Ground 45 NC Not connected
20 RSVD Reserved, Do Not Use 46 RSVD Reserved, Do Not Use
21 +5V +5V output 47 +5V +5V output
22 GND Ground 48 GND Ground
23 DIO0 Digital Input/Output 49 DIO7 Digital Input/Output
24 DIO1 Digital Input/Output 50 DIO6 Digital Input/Output
25 DIO2 Digital Input/Output 51 DIO5 Digital Input/Output
26 DIO3 Digital Input/Output 52 DIO4 Digital Input/Output
Use 16 AWG to 30 AWG wire for your signal connections.
Tighten screw terminal connections
When making connections to the screw terminals, be sure to tighten the screw until tight. Simply
touching the top of the screw terminal is not sufficient to make a proper connection.
Thermocouple input terminals (C0H/C0L to C7H/C7L)
You can connect up to eight thermocouples to the differential sensor inputs (C0H/C0L to C7H/C7L). The
USB-TC supports type types J, K, R, S, T, N, E, and B thermocouples.
Ground terminals (GND)
The six analog ground terminals (GND) provide a common ground for the input channels and DIO bits
and are isolated (500 VDC) from the USB GND.
Power terminals (+5V)
The two +5V terminals are isolated (500 VDC) from the USB +5V.
Digital terminals (DIO0 to DIO7)
You can connect up to eight digital I/O lines to the screw terminals labeled DIO0 to DIO7. Each terminal
is software configurable for input or output.
CJC sensors
The USB-TC has two built in high-resolution temperature sensors. One sensor is located on the right side
of the package, and one sensor is located at the left side.

USB-TC User's Guide Sensor Connections
3-3
Thermocouple connections
A thermocouple consists of two dissimilar metals that are joined together at one end. When the junction
of the metals is heated or cooled, a voltage is produced that correlates to temperature.
The USB-TC makes fully differential thermocouple measurements without the need of ground-
referencing resistors. A 32-bit floating point value in either a voltage or temperature format is returned by
software. An open thermocouple detection feature is available for each analog input which automatically
detects an open or broken thermocouple.
Use InstaCal to select the thermocouple type (J, K, R, S, N. E, and B) and one or more sensor input
channels to connect the thermocouple.
Wiring configuration
Connect the thermocouple to the USB-TC using a differential configuration, as shown in Figure 3-2.
I#+ NC C#H C#L 4W## IC## C#H C#L GND I#-
Figure 3-2. Typical thermocouple connection
Connect thermocouples to the USB-TC such that they are floating with respect to GND (pins 9, 19, 28,
38). The USB-TC GND pins are isolated from earth ground, so connecting thermocouple sensors to
voltages referenced to earth ground is permissible as long as the isolation between the GND pins (9, 19,
28, 38) and earth ground is maintained.
When thermocouples are attached to conductive surfaces, the voltage differential between multiple
thermocouples must remain within ±1.4 V. For best results, we recommend the use of insulated or
ungrounded thermocouples when possible.
Maximum input voltage between analog input and ground
The absolute maximum input voltage between an analog input and the isolated GND pins is ±25 VDC
when the USB-TC is powered on, and ±40 VDC when the USB-TC is powered off.
If you need to increase the length of your thermocouple, use the same type of thermocouple wires to
minimize the error introduced by thermal EMFs.
Digital I/O connections
You can connect up to eight digital I/O lines to the screw terminals labeled DIO0 to DIO7. You can
configure each digital bit for either input or output. All digital I/O lines are pulled up to +5V with a
47 K ohm resistor (default). You can request the factory to configure the resistor for pull-down to ground
if desired.
When you configure the digital bits for input, you can use the USB-TC digital I/O terminals to detect the
state of any TTL-level input. Refer to the schematic shown in Figure 3-3. If you set the switch to the +5V
input, DIO0 reads TRUE (1). If you move the switch to GND, DIO0 reads FALSE (0).
+5V+GND
DIO0
Figure 3-3. Schematic showing switch detection by digital channel DIO0

USB-TC User's Guide Sensor Connections
3-4
All ground pins on the USB-TC (pins 9, 19, 28, 38) are isolated from earth ground. If a connection is
made to earth ground when using digital I/O and conductive thermocouples, the thermocouples are no
longer isolated. In this case, thermocouples must not be connected to any conductive surfaces that may be
referenced to earth ground
For general information regarding digital signal connections and digital I/O techniques, refer to the Guide
to Signal Connections (available on our web site at www.mccdaq.com/signals/signals.pdf).