Omega OM-USB-TC-AI Owner Manual

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User’s Guide

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OM-USB-TC-AI

8 Channel

Thermocouple/Voltage Input USB

Data Acquisition Module

OMEGAnet

®

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It is the policy of OMEGA Engineering, Inc. to comply with all worldwide safety and EMC/EMI regulations that apply. OMEGA is constantly pursuing certification of its products to the European New

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The information contained in this document is believed to be correct, but OMEGA accepts no liability for any errors it contains, and reserves the right to alter specifications without notice.

WARNING: These products are not designed for use in, and should not be used for, human applications.

Table of Contents

Preface

About this User’s Guide............................................................................................................................. 5

What you will learn from this user’s guide .............................................................................................................. 5

Conventions in this user’s guide ............................................................................................................................... 5

Where to find more information ............................................................................................................................... 5

Chapter 1

Introducing the OM-USB-TC-AI................................................................................................................. 6

Overview: OM-USB-TC-AI features ....................................................................................................................... 6

OM-USB-TC-AI block diagram ............................................................................................................................... 7

Software features ....................................................................................................................................................... 7

Connecting a OM-USB-TC-AI to your computer is easy ....................................................................................... 8

Chapter 2

Installing the OM-USB-TC-AI..................................................................................................................... 9

What comes with your OM-USB-TC-AI shipment? ............................................................................................... 9

Hardware .....................................................................................................................................................................................9

Additional documentation ..........................................................................................................................................................9

Unpacking the OM-USB-TC-AI............................................................................................................................... 9

Installing the software ............................................................................................................................................. 10

Installing the OM-USB-TC-AI ............................................................................................................................... 10

Configuring the OM-USB-TC-AI........................................................................................................................... 10

Calibrating the OM-USB-TC-AI ............................................................................................................................ 10

Chapter 3

Signal I/O Connections ............................................................................................................................ 11

Screw terminal pin out ............................................................................................................................................ 11

Voltage input terminals (±V0H/V0L to ±V3H/V3L) .............................................................................................................12

Thermocouple input terminals (T0H/T0L to T3H/T3L).........................................................................................................12

Ground terminals (GND)..........................................................................................................................................................13

Power terminals (+5V) .............................................................................................................................................................13

Digital terminals (DIO0 to DIO7)............................................................................................................................................13

Counter terminal (CTR) ...........................................................................................................................................................13

CJC sensor.................................................................................................................................................................................13

Thermocouple connections ..................................................................................................................................... 13

Wiring configuration ................................................................................................................................................................13

Digital I/O connections ........................................................................................................................................... 14

Chapter 4

Functional Details ..................................................................................................................................... 15

Thermocouple measurements ................................................................................................................................. 15

Cold junction compensation (CJC) ..........................................................................................................................................15

Data linearization......................................................................................................................................................................15

Open-thermocouple detection (OTD) ......................................................................................................................................15

USB connector......................................................................................................................................................... 15

LED.......................................................................................................................................................................... 16

Power ....................................................................................................................................................................... 16

Chapter 5

Specifications............................................................................................................................................ 17

Analog input ............................................................................................................................................................ 17

Channel configurations ........................................................................................................................................... 18

3

OM-USB-TC-AI User's Guide

Compatible sensors: T0x-T3x..................................................................................................................................................19

Accuracy.................................................................................................................................................................. 19

Thermocouple measurement accuracy: T0x-T3x....................................................................................................................19

Absolute Accuracy: V0x-V3x..................................................................................................................................................20

Settling time: V0x-V3x ............................................................................................................................................................21

Analog input calibration.......................................................................................................................................... 21

Throughput rate ....................................................................................................................................................... 21

Digital input/output ................................................................................................................................................. 22

Counter..................................................................................................................................................................... 22

Memory.................................................................................................................................................................... 23

Microcontroller........................................................................................................................................................ 23

USB +5V voltage .................................................................................................................................................... 23

Power ....................................................................................................................................................................... 23

USB specifications .................................................................................................................................................. 23

Environmental ......................................................................................................................................................... 24

Mechanical............................................................................................................................................................... 24

Screw terminal connector type and pin out ............................................................................................................ 24

4

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 OM-USB-TC-AI so that you get the most out of its USB-based thermocouple and voltage measurement features.

This user’s guide also refers you to related documents available on our web site, and to technical support resources.

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.

<#:#>

bold text

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 is used for the 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 is used for the names of manuals and help topic titles, and to emphasize a word or phrase. For example:

Never touch the exposed pins or circuit connections on the board.

Where to find more information

For additional information relevant to the operation of your hardware, refer to the Documents subdirectory where you installed the software, or search for your device on our website at www.omega.com

.

5

Chapter 1

Introducing the OM-USB-TC-AI

Overview: OM-USB-TC-AI features

This user's guide contains all of the information you need to connect the OM-USB-TC-AI to your computer and to the signals you want to measure.

The OM-USB-TC-AI is a USB 2.0 full-speed, thermocouple input module that is supported under popular

Microsoft ® Windows ® operating systems. The OM-USB-TC-AI is fully compatible with both USB 1.1 and USB

2.0 ports.

The OM-USB-TC-AI provides eight analog input channels that are configured as four differential temperature inputs and four differential or single-ended voltage inputs. A 24-bit analog-to-digital (A/D) converter is provided for each pair of analog inputs. 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.

The temperature channels are software programmable for different thermocouple types. You can take measurements from type J, K, R, S, T, N, E, and B thermocouples.

The voltage input range is software programmable for ±10 V, ±5 V, ±2.5 V, ±1.25 V.

The OM-USB-TC-AI provides a integrated cold junction compensation (CJC) sensor for thermocouple measurements. An open thermocouple detection feature lets you detect a broken thermocouple.

An on-board microprocessor automatically linearizes the measurement data.

The OM-USB-TC-AI 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 OM-USB-TC-AI is fully software calibrated.

6


OM-USB-TC-AI block diagram

OM-USB-TC-AI functions are illustrated in the block diagram shown here.

Introducing the OM-USB-TC-AI

Figure 1. OM-USB-TC-AI functional block diagram

Software features

For information on the features of InstaCal and the other software included with your OM-USB-TC, refer to the

OMB-DAQ-2416 Series and OM-USB Series Software User’s Guide that shipped with your device.

7

OM-USB-TC-AI User's Guide Introducing the OM-USB-TC-AI

Connecting a OM-USB-TC-AI to your computer is easy

Installing a data acquisition device has never been easier.

The OM-USB-TC-AI 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 OM-USB-TC-AI. No third-party device driver is required.

The OM-USB-TC-AI is plug-and-play. There are no jumpers to position, DIP switches to set, or interrupts to configure.

You can connect the OM-USB-TC-AI 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 USB 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.

8

Installing the OM-USB-TC-AI

What comes with your OM-USB-TC-AI shipment?

The following items are shipped with the OM-USB-TC-AI.

Hardware

OM-USB-TC-AI

Chapter 2

USB cable (2 meter length)

Additional documentation

In addition to this hardware user's guide, you should also receive the OMB-DAQ-2416 Series and OM-USB

Series Software User’s Guide. This booklet supplies a brief description of the software you received with your

OM-USB-TC-AI and information regarding installation of that software. Please read this booklet completely before installing any software or hardware.

Unpacking the OM-USB-TC-AI

As with any electronic device, you should take care while handling to avoid damage from static electricity. Before removing the OM-USB-TC-AI 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 any components are missing or damaged, notify Omega Engineering immediately by phone, fax, or e-mail.

Phone: (203) 359-1660

Fax: (203) 359-7700

Email: [email protected]

9

OM-USB-TC-AI User's Guide Installing the OM-USB-TC-AI

Installing the software

Refer to the OMB-DAQ-2416 Series and OM-USB Series Software User’s Guide for instructions on installing the software on the OMB-DAQ-2416 Series and OM-USB Series Data Acquisition Software CD. This booklet is available in PDF at http://omega.com/manuals .

We recommend that you download the latest Windows Update onto your computer before installing and operating the OM-USB-TC-AI.

Installing the OM-USB-TC-AI

To connect the OM-USB-TC-AI 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 OM-USB-TC-AI.

When you connect the OM-USB-TC-AI for the first time, a notification message opens as the OM-USB-TC-AI is detected. When this message closes, the installation is complete. The

USB LED

should flash and then remain lit. This indicates that communication is established between the OM-USB-TC-AI and your computer.

If the LED turns off

If the LED is lit but then turns off, the computer has lost communication with the OM-USB-TC-AI. 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.

Configuring the OM-USB-TC-AI

All hardware configuration options on the OM-USB-TC-AI are programmable with software. Use InstaCal to set the thermocouple type for each channel pair.

Use InstaCal to set the thermocouple type for each for each pair of temperature channels, and the range and input configuration of each voltage channel. Any channel you don’t intend to use should be left disabled.

Configuration options are stored on the OM-USB-TC-AI 's isolated microcontroller in EEPROM, which is nonvolatile memory on the OM-USB-TC-AI module. Configuration options are loaded on power up. The factory default configuration is Type J thermocouple.

Default configuration

The factory default configuration for the voltage inputs is Disabled. The Disabled mode disconnects the analog inputs from the terminal blocks and internally grounds all of the A/D inputs.

Warm up

Allow the OM-USB-TC-AI 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 OM-USB-TC-AI

The OM-USB-TC-AI is fully calibrated via InstaCal. Allow the OM-USB-TC-AI to operate for at least 30 minutes before calibrating. This warm up time minimizes thermal drift and achieves the specified rated accuracy of measurements.

10

Chapter 3

Signal I/O Connections

Screw terminal pin out

The OM-USB-TC-AI 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 screw terminals 10 and 11 is the integrated

CJC sensor used for thermocouple measurements. Signals are identified in Figure 2.

Figure 2. OM-USB-TC-AI screw terminal pin numbers

11

OM-USB-TC-AI User's Guide Signal I/O Connections

OM-USB-TC-AI screw terminal descriptions

Pin Signal Name

1

2

RSVD

NC

5

6

3

4

7

8

9

10

T0H

T0L

4W01

RSVD

T1H

T1L

GND

RSVD

Pin Description

Reserved, Do Not Use

T0 sensor input (+)

T0 sensor input (-)

T0/T1 4-wire, 2 sensor common


T1 sensor input (+)

T1 sensor input (-)


11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

CJC sensor

RSVD

NC

T2H

T2L

4W23

RSVD

T3H

T3L

GND

RSVD

+5V

GND

NC

NC

NC

NC


T2 sensor input (+)

T2 sensor input (-)

T2/T3 4-wire, 2 sensor common


T3 sensor input (+)

T3 sensor input (-)


+5V output

Use 16 AWG to 30 AWG wire for your signal connections.

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

29

30

31

32

33

34

Pin Signal Name Pin Description

27

28

GND

V3L V3 voltage input (-)

V3 voltage input (+)

35

36

V3H

GND

V2L

V2H

GND

V1L

V1H

GND

V2 voltage input (-)




V0L

V0H

GND

CTR

DIO7

DIO6

DIO5

DIO4

DIO3

DIO2

DIO1

DIO0

GND

NC

NC

NC



Counter Input

Digital Input/Output








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.

Voltage input terminals (±V0H/V0L to ±V3H/V3L)

You can connect up to four voltage inputs to the voltage channels (V0H/V0L to V3H/V3L). The input range is software programmable for ±10 V, ±5 V, ±2.5 V, or ±1.25 V. Each voltage channel is software configurable for differential or single-ended mode.

When connecting differential inputs to floating input sources, you must provide a DC return path from each differential input to ground. One way to do this is to connect a resistor from one side of each of the differential inputs to GND. A value of approximately 100 k_ can be used for most applications.

All ground pins on the OM-USB-TC-AI (pins 9, 19, 22, 27, 30, 33, 36, 39, 49) are common and 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.

Thermocouple input terminals (T0H/T0L to T3H/T3L)

You can connect up to four thermocouples to the differential sensor inputs (T0H/T0L to T3H/T3L). The OM-

USB-TC-AI supports type J, K, R, S, T, N, E, and B thermocouples. You can mix thermocouple types (J, K, R,

S, T, N, E, and B).

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.

12

OM-USB-TC-AI User's Guide Signal I/O Connections

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.

Counter terminal (CTR)

The

CTR

terminal (pin 40) is the input to the 32-bit event counter. The internal counter increments when the

TTL level transitions from low to high. The counter can count events at frequencies of up to 1 MHz.

Caution! All ground pins on the OM-USB-TC-AI (pins 9, 19, 22, 27, 30, 33, 36, 39, 49) are common and 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.

CJC sensor

The OM-USB-TC-AI has one built-in high-resolution temperature sensor. The CJC sensor measures the ambient temperature at the terminal block so that the cold junction voltage can be calculated.

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 OM-USB-TC-AI makes fully differential thermocouple measurements without the need of groundreferencing 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 thermocouple input which automatically detects an open or broken thermocouple.

Use InstaCal to select the thermocouple type (J, K, R, S, T, N, E, and B) on one or more sensor input channels to connect the thermocouple.

Wiring configuration

Connect the thermocouple to the OM-USB-TC-AI using a differential configuration, as shown in Figure 3.

Figure 3. Typical thermocouple connection

Connect thermocouples to the OM-USB-TC-AI such that they are floating with respect to GND (pins 9, 19, 28,

38). The OM-USB-TC-AI GND pins are isolated from earth ground, so connecting thermocouple sensors to

13

OM-USB-TC-AI User's Guide Signal I/O Connections 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

OM-USB-TC-AI is powered on, and ±40 VDC when the OM-USB-TC-AI 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_ 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 OM-USB-TC-AI digital I/O terminals to detect the state of a TTL-compatible device. Refer to the schematic shown in Figure 4. If you set the switch to the +5V input, DIO0 reads TRUE (1). If you move the switch to GND, DIO0 reads FALSE (0).

Figure 4. Schematic showing switch detection by digital channel DIO0

All ground pins on the OM-USB-TC-AI (pins 9, 19, 22, 27, 30, 33, 36, 39, 49) 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 http://www.omega.com/manuals/manualpdf/M4830.pdf

).

14

Chapter 4

Functional Details

Thermocouple measurements

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 OM-USB-TC-AI hardware level-shifts the thermocouple’s output voltage into the A/D’s common mode input range by applying +2.5 V to the thermocouple’s low side at the C#L input. Always connect thermocouple sensors to the OM-USB-TC-AI in a floating fashion. Do not attempt to connect the thermocouple low side C#L to GND or to a ground referencing resistor.

Cold junction compensation (CJC)

When you connect the thermocouple sensor leads to the sensor input channel, the dissimilar metals at the OM-

USB-TC-AI terminal blocks produce two additional thermocouple junctions. This junction creates a small voltage error term which must be removed from the overall sensor measurement using a cold junction compensation technique. The measured voltage includes both the thermocouple voltage and the cold junction voltage. To compensate for the additional cold junction voltage, the OM-USB-TC-AI subtracts the cold junction voltage from the thermocouple voltage.

The OM-USB-TC-AI has one high-resolution temperature sensor integrated into the design. The CJC sensor measures the average temperature at the terminal block so that the cold junction voltage can be calculated. A software algorithm automatically corrects for the additional thermocouples created at the terminal blocks by subtracting the calculated cold junction voltage from the analog input's thermocouple voltage measurement.

Increasing the thermocouple length

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.

Data linearization

After the CJC correction is performed on the measurement data, an on-board microcontroller automatically linearizes the thermocouple measurement data using National Institute of Standards and Technology (NIST) linearization coefficients for the selected thermocouple type.

The measurement data is then output as a 32-bit floating point value in the configured format (voltage or temperature).

Open-thermocouple detection (OTD)

The OM-USB-TC-AI is equipped with open-thermocouple detection for each analog input channel. With OTD, any open-circuit or short-circuit condition at the thermocouple sensor is detected by the software. An open channel is detected by driving the input voltage to a negative value outside the range of any thermocouple output. The software recognizes this as an invalid reading and flags the appropriate channel. The software continues to sample all channels when OTD is detected.

USB connector

The USB connector provides +5V power and communication. No external power supply is required.

15

OM-USB-TC-AI User's Guide Functional Details

LED

The LED indicates the communication status of the OM-USB-TC-AI. It uses up to 5 mA of current. The table below defines the function of the OM-USB-TC-AI LED.

LED Illumination

LED

Illumination

Steady green

Pulsing green

Indication

The OM-USB-TC-AI is connected to a computer or external USB hub.

Data is being transferred.

Upon connection, the LED should flash three times and then remain lit (indicates a successful installation).

Power

The two +5V terminals are isolated (500 VDC) from the USB +5V.

Caution! Each +5V terminal is an output. Do not connect to an external power supply or you may damage the OM-USB-TC-AI and possibly the computer.

16

Chapter 5

Specifications

All specifications are subject to change without notice.

Typical for 25 °C unless otherwise specified.

All specifications apply to all temperature and voltage input channels unless otherwise specified.

Specifications in italic text are guaranteed by design.

Analog input

Parameter

A/D converter type

Number of channels

Input isolation

Channel configuration

Analog input modes

Input ranges

Absolute maximum input voltage

Input impedance

Input leakage current

Table 1. Generic analog input specifications

Conditions

T0x-T3x, V0x-V3x

Voltage input

V0x-V3x

Temperature input

T0x-T3x

Specification

AD42_321

Dual 24-bit Sigma-Delta

4 differential

4 single-ended

4 differential

T0x-T3x

V0x-V3x

Power up and reset state

Single-ended

Differential

500 VDC minimum between field wiring and USB interface

Temperature input.

Software programmable to match sensor type

Voltage input

Factory default configuration is Disabled mode.

Once configured, each channel reverts to the mode previously set by the user.

Vx_H inputs are connected directly to their screw terminal pins.

Vx_L inputs are disconnected from their screw terminal pins and internally connected to GND.

Vx_H and Vx_L inputs are connected directly to their screw terminal pins.

Tx_H and Tx_L inputs are connected directly to their screw terminal pins.

±0.080 V Thermocouple

T0x-T3x

Voltage

V0x-V3x

T0x-T3x relative to GND

(pins 9, 19, 22, 27, 30, 33, 36, 39, 49)

V0x-V3x relative to GND

(pins 9, 19, 22, 27, 30, 33, 36, 39, 49)

T0x-T3x

V0x-V3x

±10 V, ±5 V, ±2.5 V, ±1.25 V software selectable

±25 V maximum (power on)

±40 V maximum (power off)

±25 V maximum (power on)

±15 V maximum (power off)

5 Gigohm (power on)

1Mohm (power off)

10 Gigohm (power on)

2.49 kohm (power off)

30 nA maximum T0x-T3x, with open thermocouple detect disabled.

T0x-T3x, with open thermocouple detect enabled.

V0x-V3x

105 nA maximum

±1.5 nA typical., ±25 nA maximum

17

OM-USB-TC-AI User's Guide Specifications

Parameter

Input bandwidth (-3 dB)

Conditions

T0x-T3x

V0x-V3x

V0x-V3x Maximum working voltage (signal + common mode)

Common mode rejection ratio

ADC Resolution

ADC No missing codes

Input coupling

Warm-up time

Open thermocouple detect

CJC sensor accuracy

T0x-T3x, f

IN

= 60 Hz

V0x-V3x, f

IN

= 60 Hz, all input ranges

T0x-T3x

T0x-T3x, 15 °C to 35 °C

T0x-T3x, 0°C to 70 °C

Specification

50 Hz

3 kHz

±10.25 V maximum

100 dB

83 dB

24 bits

24 bits

DC

30 minutes minimum

Automatically enabled when the channel pair is configured for thermocouple sensor.

The maximum open detection time is 3 seconds.

±0.25 °C typical,±0.5 °C maximum

–1.0 to +0.75 °C maximum

Channel configurations

Table 2. Channel configuration specifications

Channel Category Conditions Specification

T0x-T3x

T0x-T3x

V0x-V3x

V0x-V3x

V0x-V3x

Note 1:

Note 2:

Note 3:

Note 4:

Disabled All temperature input channels are disconnected from screw terminals and internally connected to GND.

See Note 4

Thermocouple

Note 1

Disabled All voltage input channels are disconnected from screw terminals and internally connected to GND.

4 differential channels

See Note 4

Differential

Note 2

Single-ended

4 differential channels

4 single-ended channels

Internally, the OM-USB-TC-AI has four, dual-channel, fully differential A/Ds providing a total of eight input channels.

When connecting differential inputs to floating input sources, you must provide a DC return path from each differential input to ground. To do this, connect a resistor from each of the differential inputs to GND. A value of approximately 1Meg ohm can be used for most applications.

Channel configuration information is stored in the EEPROM of the isolated microcontroller by the firmware whenever any item is modified. Modification is performed by commands issued over USB from an external application, and the configuration is made non-volatile through the use of the EEPROM.

The factory default configuration is

Disabled

. The Disabled mode will disconnect the temperature and voltage inputs from the terminal blocks and internally connect ground (GND) to all of the A/D inputs.

18


Compatible sensors: T0x-T3x

Table 3. Compatible sensor type specifications

Parameter

Thermocouple

Conditions

J: -210 °C to 1200 °C

K: -270 °C to 1372 °C

R: -50 °C to 1768 °C

S: -50 °C to 1768 °C

T: -270 °C to 400 °C

N: -270 °C to 1300 °C

E: -270 °C to 1000 °C

B: 0 °C to 1820 °C

Accuracy

J

Thermocouple measurement accuracy: T0x-T3x

Table 4. Thermocouple accuracy specifications, including CJC measurement error. All specifications are (±)

Sensor

Type

K

S

R

B

E

T

N

Sensor temperature range

700 °C

1820 °C

-200 °C

0 °C

1000 °C

-200 °C

0 °C

400 °C

-200 °C

0 °C

1300 °C

-210 °C

0 °C

1200 °C

-210 °C

0 °C

1372 °C

-50 °C

250 °C

1768 °C

-50 °C

250 °C

1768 °C

250 °C

Accuracy error maximum

(°C)

0.931

1.225

0.554

0.480

1.301

0.549

0.400

2.193

2.028

0.835

0.783

2.137

0.842

0.822

0.469

1.976

0.954

0.653

2.082

0.870

0.568

2.197

0.848

0.653

Accuracy error typical

(°C)

0.819

0.468

0.684

0.321

0.240

0.744

0.290

0.208

0.760

0.283

0.245

0.389

0.435

0.195

0.157

0.458

0.190

0.134

2.185

0.707

0.278

0.288

0.762

0.280

Tempco

(°C/°C)

0.031

0.035

0.021

0.019

0.001

0.030

0.035

0.028

19


Note 5:

Note 6:

Note 7:

Thermocouple measurement accuracy specifications include polynomial linearization, coldjunction compensation and system noise. These specs are for one year, or 3000 operating hours, whichever comes first, and for operation of the OM-USB-TC-AI between 15 °C and 35 °C. There is a CJC sensor on the temperature sensor input side of the module. The accuracy listed above assumes the screw terminals are at the same temperature as the CJC sensor. Errors shown do not include inherent thermocouple error. Contact your thermocouple supplier for details on the actual thermocouple accuracy error.

Thermocouples must be connected to the OM-USB-TC-AI such that they are floating with respect to GND (pins 9, 19, 22, 27, 30, 33, 36, 39, 49). The OM-USB-TC-AI GND pins are isolated from earth ground. You can connect thermocouple sensors to voltages referenced to earth ground as long as the isolation between the GND pins 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 using insulated or ungrounded thermocouples when possible.

Absolute Accuracy: V0x-V3x

Table 5. Calibrated absolute accuracy specifications

Range Absolute Accuracy

(mV)

±10 V

±5 V

±2.5 V

±2.779

±1.398

±0.707

±1.25 V ±0.362

Note 8:

Note 9:

Note 10:

When connecting differential inputs to floating input sources, the user must provide a ground return path from each differential input to ground. To do this, simply connect a resistor from each of the differential inputs to GND. A value of approximately 1Meg ohm can be used for most applications.

All ground pins on the OM-USB-TC-AI (pins 9, 19, 22, 27, 30, 33, 36, 39, 49) are common and are isolated from earth ground. If a connection is made to earth ground when using both voltage inputs 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

Unused voltage inputs should not be left floating. These inputs should be placed in the Disabled mode or connected to GND.

Table 6. Accuracy components. All values are (±)

Range Gain error

(% of reading)

Offset error

(µV)

INL error

(% of range)

±10 V

±5 V

±2.5 V

±1.25 V

0.0246

0.0246

0.0246

0.0246

16.75

16.75

16.75

16.75

0.0015

0.0015

0.0015

0.0015

Gain Temperature

Coefficient

(ppm/°C)

3.68

3.68

3.68

3.68

Offset Temperature

Coefficient

(µV/°C)

0.42

0.42

0.42

0.42

20


Table 7. Noise performance specifications

Range

±10 V

±5 V

±2.5 V

±1.25 V

Peak to peak noise

(µV)

41.13

30.85

17.14

11.14

RMS noise

(µVrms)

6.23

4.67

2.60

1.69

Noise-Free resolution

(bits)

19.09

18.51

18.36

17.98

Table 7 summarizes the noise performance for the OM-USB-TC-AI. Noise distribution is determined by gathering 1000 samples with inputs tied to ground at the user connector. Samples are gathered at the maximum specified sample rate of 2 S/s.

Settling time: V0x-V3x

Table 8. Settling time specifications

Range Accuracy

±10 V

±5 V

±2.5 V

±1.25 V

±0.0004%

(seconds)

15.0

0.40

0.40

0.40

Settling time is defined as the time required for a channel to settle within a specified accuracy in response to a full-scale (FS) step input.

Analog input calibration

Table 9. Analog input calibration specifications

Parameter

Recommended warm-up time

Calibration

Calibration interval

Calibration reference

Specifications

30 minutes minimum

Firmware calibration

1 year

+10.000 V, ±5 mV maximum. Actual measured values stored in EEPROM

Tempco: 5 ppm/°C maximum

Long term stability: 30 ppm/1000 h

Throughput rate

Table 10. Throughput rate specifications

Number of Input Channels Maximum throughput

7

8

5

6

3

4

1

2

2 Samples/second

2 S/s on each channel, 4 S/s total







21


Note 11:

The analog inputs are configured to run continuously. Each channel is sampled twice per second.

The maximum latency between when a sample is acquired and the voltage/temperature data is provided by the USB unit is approximately 0.4 seconds.

Digital input/output

Table 11. Digital input/output specifications

Digital type

Number of I/O

Configuration

5V CMOS

8 (DIO0 through DIO7)

Independently configured for input or output.

Power on reset is input mode.

Pull-up/pull-down configuration All pins pulled up to +5 V via 47 K resistors (default). Contact MCC factory for pulldown to ground (GND) capability.

Digital I/O transfer rate

(software paced)

Digital input – 50 port reads or single bit reads per second typical.

Digital output – 100 port writes or single bit writes per second typical.

Input high voltage 2.0 V minimum, 5.5 V absolute maximum.

Input low voltage

Output low voltage

(IOL = 2.5 mA max.)

Output high voltage

(IOH = -2.5 mA max.)

0.8 V maximum, –0.5 V absolute minimum

0.7 V maximum

3.8 V minimum

Note 12: All ground pins on the OM-USB-TC-AI (pins 9, 19, 22, 27, 30, 33, 36, 39, 49) are common and 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.

Counter

Parameter

Pin name

Number of channels

Resolution

Counter type

Input type

Input source

Counter read/writes rates

(software paced)

Schmidt trigger hysteresis

Input leakage current

Input frequency

High pulse width

Low pulse width

Input high voltage

Input low voltage

Table 12. CTR I/O specifications

Conditions

Counter read

Counter write

Specification

CTR

1

32-bits

Event counter

TTL, rising edge triggered

CTR screw terminal

System dependent, 33 to 1000 reads per second.

System dependent, 33 to 1000 reads per second.

20 mV to 100 mV

±1.0 µA typ.

1 MHz max.

500 nS min.

500 ns min.

4.0 V min, 5.5 V absolute max

1.0 V max, –0.5 V absolute min

22


Note 13:

All ground pins on the OM-USB-TC-AI (pins 9, 19, 22, 27, 30, 33, 36, 39, 49) are common and are isolated from earth ground. If a connection is made to earth ground with both the counter

(CTR) 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.

Memory

EEPROM

Table 13. Memory specifications

1,024 bytes isolated micro reserved for sensor configuration

256 bytes USB micro for external application use

Microcontroller

Type

Table 14. Microcontroller specifications

Two high-performance 8-bit RISC microcontrollers

USB +5V voltage

Parameter

USB +5V (VBUS) input voltage range

Table 15. USB +5V voltage specifications

Specification

4.75 V minimum to 5.25 V maximum

Power

Table 16. Power specifications

Parameter Conditions Specification

Supply current

Supply current

(Note 14)

User +5V output voltage range

(terminal block pin 21)

User +5V output current

(terminal block pin 21)

Isolation

Note 14:

USB enumeration

Continuous mode with all inputs configured for Disabled mode.

Bus-powered and connected to a self-powered hub.

(Note 14)

Measurement system to PC

<100 mA

270 mA typical

4.9 V minimum to

5.1 V maximum

5 mA maximum

500 VDC minimum

This is the total current requirement for the OM-USB-TC-AI which includes up to 10 mA for the status LED.

USB specifications

USB device type

Device compatibility

Device power capability

USB cable type

USB cable length

Table 17. USB specifications

USB 2.0 (full-speed)

USB 1.1, USB 2.0

Self-powered

A-B cable, UL type AWM 2527 or equivalent. (min 24 AWG VBUS/GND, min 28 AWG D+/D–)

3 meters maximum

23


Environmental

Operating temperature range

Storage temperature range

Humidity

Mechanical

Table 18. Environmental specifications

0 to 55 ° C maximum

-40 to 85 ° C maximum

0 to 90% non-condensing maximum

Dimensions

User connection length

Table 19. Mechanical specifications

127 mm (L) x 88.9 mm (W) x 35.56 (H)

3 meters maximum

Screw terminal connector type and pin out

Table 20. Screw terminal connector specifications

Connector type

Wire gauge range

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

4

5

6

7

2

3

Pin Signal Name

1 RSVD

NC

T0H

T0L

NC

RSVD

T1H

8

9

10

T1L

GND

RSVD

CJC sensor

RSVD

NC

T2H

T2L

NC

RSVD

T3H

T3L

GND

RSVD

+5V

GND

NC

NC

NC

NC

Screw terminal

16 AWG to 30 AWG

Table 21. Screw terminal pin out

Pin Description


T0 sensor input (+)

T0 sensor input ( )


T1 sensor input (+)

T1 sensor input ( )


30

31

32

33

Pin Signal Name Pin Description

27 GND

28

29

V3L

V3H



GND

V2L

V2H

GND



34

35

36

V1L

V1H

GND




T2 sensor input (+)

T2 sensor input ( )


T3 sensor input (+)

T3 sensor input ( )


+5V output

V0L

V0H

GND

CTR

DIO7

DIO6

DIO5

DIO4

DIO3

DIO2

DIO1

DIO0

GND

NC

NC

NC

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52



Counter Input









Specifications

24

WARRANTY/DISCLAIMER

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a period of 13 months from date of purchase. OMEGA’s WARRANTY adds an additional one (1) month grace period to the normal one (1) year product warranty to cover handling and shipping time. This ensures that OMEGA’s customers receive maximum coverage on each product.

If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer Service

Department will issue an Authorized Return (AR) number immediately upon phone or written request.

Upon examination by OMEGA, if the unit is found to be defective, it will be repaired or replaced at no charge. OMEGA’s WARRANTY does not apply to defects resulting from any action of the purchaser, including but not limited to mishandling, improper interfacing, operation outside of design limits, improper repair, or unauthorized modification. This WARRANTY is VOID if the unit shows evidence of having been tampered with or shows evidence of having been damaged as a result of excessive corrosion; or current, heat, moisture or vibration; improper specification; misapplication; misuse or other operating conditions outside of OMEGA’s control. Components in which wear is not warranted, include but are not limited to contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However,

OMEGA neither assumes responsibility for any omissions or errors nor assumes liability for any damages that result from the use of its products in accordance with information provided by

OMEGA, either verbal or written. OMEGA warrants only that the parts manufactured by the company will be as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR

REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF

TITLE, AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY

AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF

LIABILITY: The remedies of purchaser set forth herein are exclusive, and the total liability of

OMEGA with respect to this order, whether based on contract, warranty, negligence, indemnification, strict liability or otherwise, shall not exceed the purchase price of the component upon which liability is based. In no event shall OMEGA be liable for consequential, incidental or special damages.

CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a “Basic

Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in medical applications or used on humans. Should any Product(s) be used in or with any nuclear installation or activity, medical application, used on humans, or misused in any way, OMEGA assumes no responsibility as set forth in our basic WARRANTY/DISCLAIMER language, and, additionally, purchaser will indemnify

OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the

Product(s) in such a manner.

RETURN REQUESTS/INQUIRIES

Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE

RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED RETURN

(AR) NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID

PROCESSING DELAYS). The assigned AR number should then be marked on the outside of the return package and on any correspondence.

The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent breakage in transit.

FOR WARRANTY RETURNS, please have the following information available BEFORE contacting OMEGA:

1. Purchase Order number under which the product was PURCHASED,

2. Model and serial number of the product under warranty, and

3. Repair instructions and/or specific problems relative to the product.

FOR NON-WARRANTY REPAIRS, consult OMEGA for current repair charges. Have the following information available BEFORE contacting OMEGA:

1. Purchase Order number to cover the COST of the repair,

2. Model and serial number of the product, and

3. Repair instructions and/or specific problems relative to the product.

OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. This affords our customers the latest in technology and engineering.

OMEGA is a registered trademark of OMEGA ENGINEERING, INC.

© Copyright 2010 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied, reproduced, translated, or reduced to any electronic medium or machine-readable form, in whole or in part, without the prior written consent of OMEGA ENGINEERING, INC.

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