Omega OM-WEB-TC User manual

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User’s Guide

Servicing North America:
U.S.A.: Omega Engineering, Inc., One Omega Drive, P.O. Box 4047
Stamford, CT 06907-0047 USA
Toll-Free: 1-800-826-6342 (USA & Canada only)
Customer Service: 1-800-622-2378 (USA & Canada only)
Engineering Service: 1-800-872-9436 (USA & Canada only)
Tel: [phone] Fax: [phone]
e-mail: [email protected]
For Other Locations Visit omega.com/worldwide
omega.com [email protected]
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.

3
Table of Contents
Preface
About this User’s Guide .......................................................................................................................6
What you will learn from this user’s guide.........................................................................................................6
Conventions in this user's guide .........................................................................................................................6
Where to find more information.........................................................................................................................6
Chapter 1
Introducing the OM-WEB Series..........................................................................................................7
Web interface......................................................................................................................................................7
TCP/IP connection............................................................................................................................................................ 7
Browser requirement......................................................................................................................................................... 7
OM-WEB Series features ...................................................................................................................................7
Temperature input channels.............................................................................................................................................. 7
Alarms .............................................................................................................................................................................. 8
Digital I/O channels.......................................................................................................................................................... 8
Functional block diagram...................................................................................................................................9
Software features................................................................................................................................................9
Chapter 2
Installing a OM-WEB Series Device ..................................................................................................10
What comes with your shipment?.....................................................................................................................10
Hardware .........................................................................................................................................................................10
Optional components.......................................................................................................................................................10
Documentation.................................................................................................................................................................10
Unpacking.........................................................................................................................................................10
Installing the software ......................................................................................................................................10
Connecting the AC power adapter....................................................................................................................10
Connecting OM-WEB Series hardware............................................................................................................11
Connecting to a LAN for communication within a network............................................................................................11
Connecting to a LAN for communication across networks .............................................................................................12
Connecting OM-WEB Series hardware directly to a computer .......................................................................................12
Using the web interface....................................................................................................................................14
Logging in to a device......................................................................................................................................................14
Configuring OM-WEB Series hardware using InstaCal...................................................................................14
Setting the network parameters........................................................................................................................................15
Calibrating OM-WEB Series hardware ............................................................................................................16
Warm-up period................................................................................................................................................16
Chapter 3
Signal I/O Connections.......................................................................................................................17
Screw terminals ................................................................................................................................................17
Sensor input.....................................................................................................................................................................17
Current excitation output (OM-WEB-TEMP) .................................................................................................................18
Four-wire, two sensor common (OM-WEB-TEMP)........................................................................................................18
Four-wire, two sensor common (OM-WEB-TEMP)........................................................................................................18
CJC sensors......................................................................................................................................................................18
Digital I/O........................................................................................................................................................................18
Pull-up/down....................................................................................................................................................................18
Ground.............................................................................................................................................................................18
Power output....................................................................................................................................................................18
Thermocouple connections...............................................................................................................................19
Wiring configuration........................................................................................................................................................19
RTD and thermistor connections (OM-WEB-TEMP only)..............................................................................19

OM-WEB Series User's Guide
4
Two-wire configuration ...................................................................................................................................................20
Three-wire configuration .................................................................................................................................................21
Four-wire configuration...................................................................................................................................................21
Semiconductor sensor measurements (OM-WEB-TEMP only).......................................................................22
Wiring configuration........................................................................................................................................................22
Digital I/O connections.....................................................................................................................................23
Configuring the DIO channels to generate alarms ...........................................................................................................23
Chapter 4
Functional Details ...............................................................................................................................24
Thermocouple measurements ...........................................................................................................................24
Cold junction compensation (CJC)..................................................................................................................................24
Data linearization.............................................................................................................................................................24
Open-thermocouple detection (OTD) ..............................................................................................................................24
RTD and thermistor measurements (OM-WEB-TEMP only)..........................................................................24
Data linearization.............................................................................................................................................................25
External components ........................................................................................................................................25
Screw terminals................................................................................................................................................................25
Ethernet port ....................................................................................................................................................................25
External power connector ................................................................................................................................................25
Status LEDs.....................................................................................................................................................................26
Digital logic voltage switch .............................................................................................................................................26
Factory default reset button..............................................................................................................................................26
Chapter 5
Ethernet Troubleshooting ..................................................................................................................27
Check the OM-WEB Series device status LEDs..............................................................................................27
Check the network settings on the computer....................................................................................................28
Check whether DHCP is enabled on the network server..................................................................................................28
Verify that the computer is connected to the network ......................................................................................28
Verify the network path to the OM-WEB Series device ..................................................................................29
Verify the network path to a remote OM-WEB Series device..........................................................................30
Check cached information................................................................................................................................30
Deleting a NetBIOS table entry .......................................................................................................................................30
Deleting an ARP table .....................................................................................................................................................30
Getting help ......................................................................................................................................................30
Chapter 6
Specifications......................................................................................................................................31
Analog input.....................................................................................................................................................31
Channel configurations.....................................................................................................................................32
Compatible sensors...........................................................................................................................................32
Accuracy...........................................................................................................................................................33
Thermocouple measurement accuracy.............................................................................................................................33
Semiconductor sensor measurement accuracy.................................................................................................................34
RTD measurement accuracy............................................................................................................................................34
Thermistor measurement accuracy ..................................................................................................................................35
Throughput rate ................................................................................................................................................36
Digital input/output...........................................................................................................................................36
Temperature alarms..........................................................................................................................................37
Memory ............................................................................................................................................................37
Microcontroller.................................................................................................................................................37
Power................................................................................................................................................................37
Network............................................................................................................................................................38

OM-WEB Series User's Guide
5
Ethernet compliance ........................................................................................................................................................38
Ethernet connection .........................................................................................................................................................38
Network factory default settings......................................................................................................................................38
Network protocols............................................................................................................................................................39
Network security..............................................................................................................................................................39
LED displays and the factory reset button........................................................................................................39
Current excitation outputs (OM-WEB-TEMP) ................................................................................................40
Environmental ..................................................................................................................................................40
Mechanical .......................................................................................................................................................40
Screw terminal connector type and pinout .......................................................................................................40

6
Preface
About this User’s Guide
What you will learn from this user’s guide
This user's guide describes the Omega Engineering OM-WEB Series data acquisition devices and lists device
specifications.
Conventions in this user's guide
For more information about …
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 Bold text is used for the names of objects on a screen, such as buttons, text boxes, and check boxes.
italic text Italic text is used for the names of manuals and help topic titles, and to emphasize a word or phrase.
Where to find more information
Additional information about OM-WEB Series hardware is available on our website at www.omega.com. You
can also contact Omega Engineering by phone, fax, or email with specific questions.
Phone: [phone]
Fax: [phone]
Email: [email protected]m

7
Chapter 1
Introducing the OM-WEB Series
The OM-WEB Series includes the following devices:
OM-WEB-TC
OM-WEB-TEMP
OM-WEB Series devices are temperature measurement devices with built-in web servers. You can connect the
device to an Ethernet port or hub, start up your browser, and view current data.
OM-WEB Series hardware are fully supported by the Universal Library and TracerDAQ. These software
programs are included on the Software for OMB-DAQ-2400, OM-USB, OM-WEB, and OM-WLS Series Data
Acquisition Modules CD.
Web interface
The embedded web interface provides access to current data and configuration settings using a standard web
browser.
Browse to the device's home page by entering the URL that is printed on the device into the browser. View
current sensor measurements, channel data, and configure hardware options from the device's web pages. Only
one user can change configuration options on the device at a time.
The web interface is built into the device's firmware, and does not need to be installed on a computer. No
external software is required other than a web browser and a TCP/IP connection.
TCP/IP connection
A TCP/IP connection is required to access the web interface. Connect the device's 10Base-T Ethernet port to a
local or wide area network using the supplied Ethernet cable, to a single computer through a hub using the
supplied Ethernet cable, or directly to a computer using a standard CAT-5 crossover cable.
Browser requirement
The web browser used to access the web interface must support JavaScript. The web interface was tested with
the following browsers for compatibility:
Mozilla Firefox™2.x
Microsoft Internet Explorer®6.x
Microsoft Internet Explorer®7.x
OM-WEB Series features
OM-WEB Series hardware provides eight temperature channels and eight digital I/O channels. An external
supply shipped with the device provides power. On-board LEDs display the status of communication and
external power.
Configurable hardware options can be set with either InstaCal or the web browser. Configurable network
options can only be set with InstaCal. If the default login settings are changed, InstaCal requires a login name
and password to access the configuration settings.
Temperature input channels
OM-WEB Series hardware provides eight differential temperature input channels. A 24-bit analog-to-digital
(A/D) converter is provided for each pair of analog inputs. Each pair of inputs constitutes a channel pair.
The following table lists the sensor categories supported by each device.

OM-WEB Series User's Guide Introducing the OM-WEB Series
8
Supported sensor categories
Sensor category
OM-WEB-TC
OM-WEB-TEMP
Thermocouple (J, K, R, S, T, N, E, and B)


Resistance temperature detectors (RTDs)
(2, 3, or 4-wire)

Thermistors (2, 3, or 4-wire)

Semiconductor temperature sensors
(LM35, TMP35 or equivalent)

The sensor category is software-selectable for each channel pair. With the OM-WEB-TEMP, each channel pair
can connect to a different category of sensor. The sensor category between the channels that constitute a
channel pair cannot be mixed. However, thermocouple types within a channel pair can be mixed.
Four integrated cold junction compensation (CJC) sensors are provided for thermocouple measurements. Each
CJC sensor is dedicated to one of the four channel pairs. An open thermocouple detection feature lets you detect
a broken thermocouple. An on-board microprocessor automatically linearizes the measurement data according
to the sensor category. Built-in current excitation sources are provided for resistive sensor measurements (OM-
WEB-TEMP only)
Alarms
OM-WEB Series device feature eight independent temperature alarms. Each alarm controls an associated digital
I/O channel as an alarm output. The input to each alarm is one of the temperature input channels. The output of
each alarm is software-selectable as active high or low. User-configurable threshold conditions activate each
alarm. When an alarm is activated, the associated DIO channel is driven to the active output state selected.
Digital I/O channels
Eight digital I/O channels are provided to communicate with external devices and to generate alarms. The
digital bits are software-selectable for input or output. The digital output voltage is switch-selectable for 3.3 V
or 5 V logic. A screw terminal is provided for pull-up or pull-down configuration.
The digital I/O channels power up in input mode unless the bit is configured for an alarm. When a digital bit is
configured as an alarm, that bit is configured as an output and assumes the state defined by the alarm
configuration.
If you need to log data or display data graphically
OM-WEB Series devices display current data read from the device, and does not log or store historical data. For
logging or trending needs, use the TracerDAQ software included on the Software for OMB-DAQ-2400,
OM-USB, OM-WEB, and OM-WLS Series Data Acquisition Modules CD.

OM-WEB Series User's Guide Introducing the OM-WEB Series
9
Functional block diagram
OM-WEB Series device functions are illustrated in the block diagram shown here.
Figure 1. OM-WEB Series functional block diagram
Software features
For information on the features of InstaCal and the other software included with your OM-WEB Series
hardware, refer to the OMB-DAQ-2400, OM-USB, OM-WEB, and OM-WLS Series Data Acquisition Software
User's Guide that shipped with the device.

10
Chapter 2
Installing a OM-WEB Series Device
What comes with your shipment?
The following items are shipped with OM-WEB Series hardware:
Hardware
OM-WEB-TC or OM-WEB-TEMP
Ethernet cable (standard)
External power supply and cord –10 watt AC power adapter. Omega part number
OMB-DAQ-2416-ADAP.
Optional components
Crossover cable (CAT-5 or higher) to connect the OM-WEB Series device to an Ethernet adapter installed
in a computer.
Documentation
The following documentation ships with the OM-WEB Series hardware:
OMB-DAQ-2400, OM-USB, OM-WEB, and OM-WLS Series Data Acquisition Software User's Guide
This booklet provides an overview of the software you received with the device.
OM-WEB-TEMP or OM-WEB-TC Setup Options
This booklet provides an overview of three common setup configurations. Detailed installation information
is provided in this user’s guide.
Unpacking
As with any electronic device, you should take care while handling to avoid damage from static
electricity. Before removing the device 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: [phone]
Fax: [phone]
Email: [e-mail]
Installing the software
Refer to the OMB-DAQ-2400, OM-USB, OM-WEB, and OM-WLS Series Data Acquisition Software User's
Guide for instructions on installing the software on the Software for OMB-DAQ-2400, OM-USB, OM-WEB, and
OM-WLS Series Data Acquisition Modules CD. This booklet is available in PDF at
http://www.omega.com/manuals/manualpdf/M4803.pdf.
Connecting the AC power adapter
The 10 watt AC power adapter (OMB-DAQ-2416-ADAP) provides power to OM-WEB Series hardware.
Connect the adapter cord to the power connector on the device and plug the AC adapter into an electrical outlet.
The POWER/COMM LED turns on when +5 V power is supplied to the device. If the voltage supply is less than
+4.75 V or more than +5.25 V, the POWER/COMM LED will not turn on.
Refer to Figure 11 on page 25 for the location of the POWER/COMM LED.

OM-WEB Series User's Guide Installing a OM-WEB Series Device
11
Connecting OM-WEB Series hardware
A TCP/IP connection between the OM-WEB Series device and the network or computer is required to access
the device's web interface. A 10Base-T compatible Ethernet port, hub, or switch is required.
You can connect the device using the following configurations:
Connect to your Local Area Network (LAN) for communication within a private network/intranet; refer to
the procedure below.
Connect to your LAN for communication across networks (communicate over the internet, for example);
refer to the procedure on page 12.
Connect directly to a computer's Ethernet port for local access (requires a crossover cable (not provided) or
network hub); refer to the procedure on page 12.
Use the standard Ethernet cable provided to connect OM-WEB Series hardware to a TCP/IP-based local or wide
area network or to connect to a single PC through a hub or switch. Use a CAT-5 or higher crossover cable (not
provided) to connect the OM-WEB-TEMP, OM-WEB-TC to an Ethernet card installed in a computer.
How you access the web interface once a TCP/IP connection is established depends on your configuration:
When the device is connected to the same network as the computer browser, enter the URL that is printed
on the device to open the device's home page.
When the device is connected to a different network as the computer browser, enter the public IP address
set for the device to open the device's home page. Refer to "Connecting to a LAN for communication
across networks" on page 12 for more information.
Connecting to a LAN for communication within a network
Use this procedure to connect OM-WEB Series hardware to a local area network (LAN). When connected, all
computers installed on the same network can access the web interface.
Note: This procedure assumes the network server is equipped with DHCP (dynamic host configuration
protocol), and will automatically assign an IP address to the OM-WEB-TEMP, OM-WEB-TC when it is
connected to the network.
1. Connect the OM-WEB Series hardware to the network using the Ethernet cable provided.
The Link/Activity LED will turn on to indicate that you have established a valid Ethernet connection.
2. Open your web browser and enter the URL that is printed on the device label.
The OM-WEB Series Measurements page opens. Use this page to view current measurement data. A log in
name and password are required to change configuration settings.
Default login name and password
The default login name for the OM-WEB-TC is "webtc", and "webtemp" for the OM-WEB-TEMP. The default
password is "omega" for each device.
If the OM-WEB Series device is not recognized by the network
If the Measurements page does not open, the server may not have DHCP, or DHCP may be disabled on the
server. In either situation, assign a static IP address to the OM-WEB Series device before connecting to the
network. Refer to "Connecting OM-WEB Series hardware directly to a computer" on page 12 for instructions.
After you assign the static IP address, connect to the network using the standard Ethernet cable shipped with the
device, open the browser, and enter the static IP address.
Configuring OM-WEB Series hardware
All hardware options are configurable with InstaCal or the web interface. InstaCal must be used to change any
network parameters, such as the IP address of your device. Configuration settings are stored in non-volatile
memory in EEPROM, and are loaded on power up.
Refer to the sections "Using the web interface" on page 14 and "Configuring OM-WEB Series hardware using
InstaCal" on page 14 for detailed information.

OM-WEB Series User's Guide Installing a OM-WEB Series Device
12
Connecting to a LAN for communication across networks
In order to communicate with OM-WEB Series hardware from a computer connected to a different network,
such as over the internet, you must change the network configuration of the network router.
In the following procedure, the OM-WEB Series device is installed at the "host" LAN, and the computer is
installed at the "client" LAN.
Caution! This procedure should only be performed by a network administrator or computer professional.
Incorrect settings can significantly disrupt a network.
1. Connect the OM-WEB Series device to a LAN (host) that has access to the Internet using the cable
provided.
The Link/Activity LED will turn on steady green to indicate that you have established a valid Ethernet
connection.
2. Configure the OM-WEB Series device at the host LAN to access the web page:
oAssign a fixed "private" static IP address to the OM-WEB-TEMP, OM-WEB-TC.
oConfigure the firewall/router to map a static "public" IP address to the "private" IP address assigned
above. Record this address for use in step 3.
oConfigure the firewall/router to forward incoming traffic from the public IP address to the HTTP port
("port 80") of the private static IP address.
Note: If your network has an HTTP server already running, network address translation (NAT) allows
different ports to redirect to the OM-WEB Series device on port 80. Contact your network
administrator or computer professional for more information.
Note: To access OM-WEB Series hardware using InstaCal and the Universal Library, configure the
firewall to allow incoming traffic to the UDP port ("port 54211" by default).
3. At the client LAN, open your web browser, and enter the "public" IP address recorded in step 2 above.
Note: To access the OM-WEB-TEMP, OM-WEB-TC by name, a DNS entry must be assigned.
The Measurements page opens. Use this page to view current measurement data. A log in name and password
are required to change configuration settings.
Accessing OM-WEB Series hardware using InstaCal and the Universal Library
InstaCal cannot automatically detect a OM-WEB-TEMP, OM-WEB-TC that is installed on a different subnet.
To change configuration settings with InstaCal, or to communicate with OM-WEB Series hardware using
programs written with the Universal Library, manually add the public IP address to InstaCal. InstaCal can then
search the public address provided for the device. We recommend that the port number be set to 54211 for use
with InstaCal and the Universal Library. Port 80 is used for the web interface. For information on port
configuration, contact your network administrator or computer professional.
Configuring OM-WEB Series hardware
All hardware options are configurable with InstaCal or the web interface. InstaCal must be used if any of the
network parameters need to be changed, such as the IP address of your device. Configuration settings are stored
in non-volatile memory in EEPROM, and are loaded on power up.
Refer to "Using the web interface" on page 14 and "Configuring OM-WEB Series hardware using InstaCal" on
page 14 for detailed information.
Connecting OM-WEB Series hardware directly to a computer
Use this procedure to connect OM-WEB Series hardware directly to a computer. This scenario provides local
access only, and requires that you set up your computer to use a static IP address for communication with the
OM-WEB Series device. If you are not using a network hub, a CAT-5 (or higher) crossover cable is required to
connect to the computer's Ethernet port. If you are connecting to your computer through a network hub or
switch, the Ethernet cable provided with your device can be used.

OM-WEB Series User's Guide Installing a OM-WEB Series Device
13
Knowledge of network configuration is required
If you are not familiar with network configurations and have questions regarding your network settings, consult
your network administrator or a computer professional.
4. Select Start » Control Panel » Network Connections.
5. Double-click on Local Area Connection.
6. Select Internet Protocol (TCP/IP) and click Properties.
7. Select Use the following IP address option and enter the following:
oIP address: Enter 192.168.0.102. Note that the last three digits of this number can be any number
between 11 and 254, inclusive, but must be different from the IP address assigned to the device. The
default IP address set for the OM-WEB-TEMP, OM-WEB-TC is 192.168.0.101.
oSubnet mask: Enter 255.255.255.0.
oDefault gateway: Enter 192.168.0.1.
Caution! Assigning an arbitrary IP address could result in duplicate IP addresses on the network. This
condition can cause a communication failure that affects both devices. Make sure when
configuring static IP addresses that you set different addresses for each device.
8. Click OK.
9. Connect the Ethernet port on the OM-WEB Series device to your Ethernet hub using the supplied cable, or
to your computer's Ethernet port using a CAT-5 or higher crossover cable.
Note: If you connect to an Ethernet hub, you can use the Ethernet cable shipped with the device. If you
have multiple OM-WEB Series devices, configure each device separately and assign a unique IP address to
each device. You will need to run InstaCal to change the IP address from the default 192.168.0.101.
When connected, the Link/Activity LED turns on steady green to indicate that you have established a valid
Ethernet connection, and blinks to indicate network traffic. Refer to Figure 11 on page 25 for the location
of the Link/Activity LED.
10. Open your browser and enter the URL address that is printed on the device label.
The Measurements page opens. Use this page to view current measurement data.
Configuring OM-WEB Series hardware
All hardware options are configurable with InstaCal or the web interface. InstaCal must be used if any of the
network parameters need to be changed, such as the IP address of your device. Configuration settings are stored
in non-volatile memory in EEPROM, and are loaded on power up.
Refer to the sections "Using the web interface" on page 14 and "Configuring OM-WEB Series hardware using
InstaCal" on page 14 for detailed information.

OM-WEB Series User's Guide Installing a OM-WEB Series Device
14
Using the web interface
You can view current measurements and configure hardware options from the device's web interface. The web
interface provides four tabs. Each tab represents an HTML page that is stored on the device.
Measurements tab (home page) –lists the temperature measurements, digital values, and alarm status read
from each channel on the OM-WEB-TEMP, OM-WEB-TC.
System Info tab –summarizes the current network settings set for the OM-WEB Series device, and
provides a button that when pressed flashes the POWER/COMM LED on the device. The settings on this tab
are not configurable via the web interface; use InstaCal to configure network settings.
Configuration tab –provides separate menu options for configuring temperature, digital, and alarm
options. To change configuration settings, enter the user name and password set for the device and click the
Log In button. The user name and password cannot be changed from the web interface; use InstaCal to
change the user name and password.
Temperature menu
Provides options to set the sensor category and connection type for each temperature channel
pair.
The factory default configuration is Disabled. The Disabled mode disconnects the analog
inputs from the terminal blocks and internally grounds all of the A/D inputs. This mode also
disables each of the current excitation sources. Leave unused channels disabled.
DIO menu
Provides options to set the direction of each digital I/O channel and value of each digital I/O
channel configured for output.
Alarm menu
Provides options to set up the temperature conditions to activate an alarm, and the output
state of the channel (active high or low) when activated. You can configure up to eight
independent alarms.
The configuration options are enabled on these pages when you are logged in. The device is calibrated to
the selected settings each time the "Submit" or "Calibrate" button is pressed.
Help –summarizes the options on each web page, and includes step-by-step procedures for setting up your
temperature channels, digital channels, and alarms.
Logging in to a device
Configurable options are disabled until you log in with the user name and password set for the device. Only one
user can be logged in at a time. The default login name for the OM-WEB-TC is "webtc", and "webtemp" for the
OM-WEB-TEMP. The default password is "omega" for each device. Use InstaCal to change these values.
Base64 encryption is used to encrypt the login name and password. JavaScript must be enabled on the browser
to encrypt login information. If JavaScript is disabled on your browser when you log in, the user name and
password values are transmitted as plain text with no encryption applied.
Configuring OM-WEB Series hardware using InstaCal
All hardware and network options are configurable with InstaCal. When the device is using its default
configuration, InstaCal has access to all functions on the device. Login is done in the background if the default
user name and password are assigned to the device.
If the default user name and password for a device have changed, configurable options are disabled until you
log in with the user name and password set for the device. Only one user can be logged in at a time.
You should change the user name and password from the default values
To prevent unauthorized changes to your device configuration, make sure you change the user name and
password values from the default values. If you forget your settings, you can restore the default values: press
and hold the reset button for three seconds to set all network settings, including the user name and password,
back to the default values.
Note: For security purposes, do not change the log in information to the name and password used to access
secure accounts, such as a credit card or bank account.

OM-WEB Series User's Guide Installing a OM-WEB Series Device
15
Setting the network parameters
Use InstaCal to change configurable network settings set on the OM-WEB Series device. Network parameters
are not accessible via the web interface. The device is shipped configured with the following default settings:
Default network settings (temp)
Network setting
Default value
Identifier
not set, optional
DHCP setting
Enabled
IP address
192.168.0.101
Subnet mask
255.255.255.000
Gateway
192.168.0.1
Server
Enabled
User name
OM-WEB-TC: webtc
OM-WEB-TEMP: webtemp
Password
omega
MAC address
00:12:71:Cx:xx:xx, where xxxxx is the device’s serial number (read-only)
The following default network parameters are programmable with InstaCal:
Identifier
Text that identifies the WEB Series device. This value is optional, and is not set by default. Up to 48
alpha-numeric characters can be entered.
DHCP
Enables configuration by a DHCP (Dynamic Host Configuration Protocol) Server. DHCP is a service
that automatically assigns IP addresses to clients supporting the protocol. If the connected network
has a DHCP server, an IP address is assigned to the device shortly after it is powered up and attached
to the network. InstaCal will display the IP address assigned to the device.
The default DHCP setting is Enabled. Disable this setting when the server is not DHCP-enabled, or
when entering a "static" IP address. Unless there is a reason to disable DHCP (such as the network
server is not DHCP-enabled), we recommend that you leave DHCP enabled.
IP
The Internet Protocol (IP) address that is stored on the device. Use this address when a DHCP server
is not available or when DHCP is disabled.
Subnet
The Subnet Mask stored on the device. The Subnet Mask is part of the IP address and denotes the
local Subnet. Use this address when a DHCP server is not available or when DHCP is disabled.
Gateway
The Gateway IP address stored on the device. Use this address when a DHCP server is not available
or when DHCP is disabled. A gateway is the IP address of the device that bridges subnets within a
network.
Server
Enables or disables the device's web page server. Enable this value to view the device's web page
with a browser. Disable access to the web page when you want to restrict access to the device to
InstaCal or the Universal Library API.
User Name and
Password:
The user name and password used to log in to a device session. Log in is required only when
changing configurable options on the device. Change default values with InstaCal.
A unique 64-bit physical (MAC) address is also assigned to the device. This address is set at the factory and is
not user-configurable.
Restoring factory default network settings
To restore network settings to factory default values, press and hold the device's reset button for three seconds.
If InstaCal is open when default settings are restored, click the Refresh Boards button on the InstaCal tool bar
to reflect the changes.

OM-WEB Series User's Guide Installing a OM-WEB Series Device
16
Calibrating OM-WEB Series hardware
OM-WEB Series hardware is calibrated to the selected device settings each time the Submit or Calibrate button
is pressed on a web interface configuration page, or the OK button is pressed on the InstaCal board
configuration page.
Warm-up period
After you configure the hardware options, allow the OM-WEB Series device to warm up for 30 minutes before
taking measurements. This warm up time minimizes thermal drift and achieves the specified rated accuracy of
measurements. For analog, RTD or thermistor measurements, this warm-up time is also required to stabilize the
internal current reference.

17
Chapter 3
Signal I/O Connections
Screw terminals
OM-WEB Series hardware has four banks of screw terminals. Signal locations are shown in Figure 2.
Figure 2. Screw terminal pinout
1OM-WEB-TEMP only. These pins are labeled RSVD (reserved for future use) on the OM-WEB-TC.
Do not make connections to the terminals labeled NC. Use 16 AWG to 30 AWG wire for signal connections.
Tighten screw terminal connections
When making connections to the screw terminals, be sure to tighten the screw until it is tight. Simply touching
the top of the screw terminal is not sufficient to make a proper connection.
Sensor input
You can connect up to eight temperature sensors to the differential sensor inputs (C0H/C0L to C7H/C7L). Each
channel pair has a 24-bit A/D converter, and can monitor one sensor category.
The OM-WEB-TC and OM-WEB-TEMP support thermocouple types J, K, R, S, T, N, E, and B. You can
connect two different thermocouple types to a channel pair.
The OM-WEB-TEMP also supports the following temperature sensor types:
Resistance temperature detectors (RTDs) –2, 3, or 4-wire measurement modes of 100 Ω platinum RTDs.
Thermistors –2, 3, or 4-wire measurement modes.
Semiconductor temperature sensors –LM35, TMP35 or equivalent
Do not connect two different sensor categories to the same channel pair
Each channel pair can monitor one sensor category. To monitor a sensor from a different category, connect the
sensor to a different channel pair.
Sensor selection
The type of sensor you select will depend on your application needs. Review the temperature ranges and
accuracies of each sensor type to determine which is best suited for your application.

OM-WEB Series User's Guide Signal I/O Connections
18
Current excitation output (OM-WEB-TEMP)
Four dedicated pairs of current excitation output terminals (±IA to ±ID) have a built-in precision current source
to provide excitation for the resistive sensors used for RTD and thermistor measurements.
Current excitation terminals are dedicated to one pair of sensor input channels:
IA+ and IA–are the current excitation source for channel 0 and channel 1
IB+ and IB–are the current excitation source for channel 2 and channel 3
IC+ and IC–are the current excitation source for channel 4 and channel 5
ID+ and ID–are the current excitation source for channel 6 and channel 7
These terminals are labeled RSVD (reserved for future use) on the OM-WEB-TC.
Four-wire, two sensor common (OM-WEB-TEMP)
Terminals 4W01, 4W23, 4W45, and 4W67 are used as the common connection for four-wire configurations with
two RTD or thermistor sensors.
These terminals are labeled RSVD (reserved for future use) on the OM-WEB-TC.
Four-wire, two sensor common (OM-WEB-TEMP)
Terminals IC01, IC23, IC45, and IC67 are used as the common connection for four-wire configurations with two
RTD or thermistor sensors.
These terminals are labeled RSVD (reserved for future use) on the OM-WEB-TC.
CJC sensors
OM-WEB Series hardware have four built in high-resolution temperature sensors for thermocouple
measurements. Each CJC sensor is dedicated to one of the four channel pairs, and is located behind the
associated channel's screw terminal. These sensors measure the ambient temperature at the terminal block so
that the cold junction voltage can be calculated.
Digital I/O
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. A PU/D terminal is provided for pull-up/down configuration
(explained below).
If a digital bit is set up as an alarm, the bit is configured for output and assumes the state defined by the alarm
configuration.
Pull-up/down
All digital I/O lines are connected through 47k to the PU/D pin, which is floating by default. For a pull-up
configuration, connect the PU/D pin to the +5V pin. For a pull-down configuration, connect the PU/D pin to the
GND pin.
Ground
The analog ground (AGND) terminals provide a common ground for the sensor input channels. AGND pins are
isolated from the GND pin and from earth ground. Thermocouple sensors can connect to voltages that are
referenced to earth ground as long the isolation between the AGND pins and earth ground is maintained.
The ground (GND) terminal provides a common ground for the digital I/O channels. The GND pin is isolated
from the AGND pins and from earth ground.
Power output
The +5V output terminal is isolated (500 VDC) from the analog input terminals.
Caution! The +5V terminal is an output. Do not connect an external power supply to this terminal or you
may damage the OM-WEB-TEMP, OM-WEB-TC and possibly the computer.

OM-WEB Series User's Guide Signal I/O Connections
19
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.
OM-WEB Series hardware make fully differential thermocouple measurements without requiring ground-
referencing resistors. A 32-bit floating point value in either a voltage or temperature format is returned by
software. Open thermocouple detection (OTD) is available for each thermocouple input. OTD automatically
detects an open or broken thermocouple.
Use the web browser or InstaCal to select the thermocouple type (J, K, R, S, T, N, E, and B) and one or more
input channels to connect the thermocouple.
Wiring configuration
Connect the thermocouple to the device using a differential configuration, as shown in Figure 3. Note: There
are two high/low channel pairs on each terminal. The # indicates the channel number. Do not make connections
to the pin labeled "NC".
Figure 3. Typical thermocouple connection
Connect thermocouples such that they are floating with respect to AGND (pins 9, 19, 28, 38). The AGND 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 AGND 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, use 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 AGND pins is ±25 VDC when
the device is powered on, and ±40 VDC when 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.
RTD and thermistor connections (OM-WEB-TEMP only)
A resistance temperature detector (RTD) measures temperature by correlating the resistance of the RTD
element with temperature. A thermistor is a thermally-sensitive resistor that is similar to an RTD in that its
resistance changes with temperature —thermistors show a large change in resistance that is proportional to a
small change in temperature. The main difference between RTD and thermistor measurements is the method
used to linearize the sensor data.
RTDs and thermistors are resistive devices that require an excitation current to produce a voltage drop that can
be measured differentially across the sensor. OM-WEB-TEMP, OM-WEB-TCs feature four current excitation
sources (±IA to ±ID) for measuring resistive type sensors. Each current excitation source is dedicated to one
channel pair.
The OM-WEB-TEMP makes two, three, and four-wire measurements of RTDs (100 Ω platinum type) and
thermistors.

OM-WEB Series User's Guide Signal I/O Connections
20
Use InstaCal or the web interface to select the sensor type and the wiring configuration. Once the resistance
value is calculated, the value is linearized in order to convert it to a temperature value. A 32-bit floating point
value in either temperature or resistance is returned by software.
RTD maximum resistance
Resistance values greater than 660 Ω cannot be measured by the OM-WEB-TEMP in the RTD mode. The
660 Ω resistance limit includes the total resistance across the current excitation (±Ix) pins, which is the sum of
the RTD resistance and the lead resistances.
Thermistor maximum resistance
Resistance values greater than 180 kΩ cannot be measured by the OM-WEB-TEMP in the thermistor mode.
The 180 kΩ resistance limit includes the total resistance across the current excitation (±Ix) pins, which is the
sum of the thermistor resistance and the lead resistance.
Two-wire configuration
The easiest way to connect an RTD sensor or thermistor to the OM-WEB-TEMP is with a two-wire
configuration since it requires the fewest connections to the sensor. With this method, the two wires that
provide the RTD sensor with its excitation current also measure the voltage across the sensor.
Since RTDs exhibit a low nominal resistance, measurement accuracy can be affected due to the lead wire
resistance. For example, connecting lead wires that have a resistance of 1 Ω (0.5 Ω each lead) to a 100 Ω
platinum RTD will result in a 1% measurement error.
With a two-wire configuration, connect either one sensor per channel pair or two sensors per channel pair.
Two-wire, single-sensor
A two-wire single-sensor measurement configuration is shown in Figure 4. Note: There are two high/low
channel pairs on each terminal. The # indicates the channel number. Do not make connections to the pin labeled
"NC".
Figure 4. Two-wire, single RTD or thermistor sensor measurement configuration
When you select a two-wire single sensor configuration, connections to C#H and C#L are made internally.
Two-wire, two sensor
A two-wire, two-sensor measurement configuration is shown in Figure 5. Note: There are two high/low channel
pairs on each terminal. The # indicates the channel number Do not make connections to the pin labeled "NC".
Figure 5. Two-wire, two RTD or thermistor sensors measurement configuration