Rosemount 248DX User Manual
Rosemount 248 Wireless Temperature
Transmitter
Reference Manual
00809-0300-4248, Rev AA
July 2014
Reference Manual
NOTICE
00809-0300-4248, Rev AA
Rosemount 248 Wireless
Temperature Transmitter
Rosemount 248 Hardware Revision
HART® Device Revision
Field Communicator Field Device Revision
Read this manual before working with the product. For personal and system safety, and for
optimum product performance, make sure to thoroughly understand the contents before
installing, using or maintaining this product.
For technical assistance, contacts are listed below:
Customer Central
Technical support, quoting, and order-related questions.
United States - 1-800-999-9307 (7:00 am to 7:00 pm CST)
Asia Pacific- 65 777 8211
Europe/ Middle East/ Africa - 49 (8153) 9390
North American Response Center
Equipment service needs
1-800-654-7768 (24 hours—includes Canada)
Outside of these areas, contact your local Emerson Process Management representative.
1
1
Dev 1, DD v1
The products described in this document are NOT designed for nuclear-qualified
applications. Using non-nuclear qualified products in applications that require
nuclear-qualified hardware or products may cause inaccurate readings.
For information on Rosemount nuclear-qualified products, contact a Emerson Process
Management Sales Representative.
iii
Reference Manual
NOTICE
00809-0300-4248, Rev AA
Failure to follow these installation guidelines could result in death or serious injury:
Make sure only qualified personnel perform the installation.
Explosions could result in death or serious injury:
Installation of this transmitter in an explosive environment must be in accordance with
the appropriate local, national, and international standards, codes, and practices.
Please review the approvals section of the 248 reference manual for any restrictions
associated with a safe installation.
Before connecting a Field Communicator in an explosive atmosphere, ensure the
instruments are installed in accordance with intrinsically safe or non-incendive field
wiring practices.
Verify that the operating atmosphere of the transmitter is consistent with the
appropriate hazardous locations certifications.
Process leaks may cause harm or result in death.
Do not remove the thermowell while in operation.
Install and tighten thermowells and sensors before applying pressure.
Electrical shock can result in death or serious injury.
Avoid contact with the leads and terminals. High voltage that may be present on leads
can cause electrical shock.
This device complies with Part 15 of the FCC Rules. Operation is subject to the
following conditions:
This device may not cause harmful interference.
This device must accept any interference received, including interference that may
cause undesired operation.
This device must be installed to ensure a minimum antenna separation distance of 20
cm from all persons.
The Power Module may be replaced in a hazardous area. The Power Module has surface
resistivity greater than one gigaohm and must be properly installed in the wireless device
enclosure. Care must be taken during transportation to and from the point of installation to
prevent electrostatic charge build-up.
The Rosemount 248 Wireless and all other wireless devices should be installed only after the
Smart Wireless Gateway has been installed and is functioning properly. Wireless devices
should also be powered up in order of proximity from the Smart Wireless Gateway,
beginning with the closest. This will result in a simpler and faster network installation.
iv
Reference Manual
NOTICE
NOTICE
00809-0300-4248, Rev AA
Shipping considerations for wireless products (Lithium Batteries: Green Power
Module, model number 701PGNKF):
The unit was shipped to you without the Power Module installed. Please remove the Power
Module prior to shipping the unit.
Each Power Module contains one “D” size primary lithium-thionyl chloride battery. Primary
lithium batteries are regulated in transportation by the U. S. Department of Transportation,
and are also covered by IATA (International Air Transport Association), ICAO (International
Civil Aviation Organization), and ARD (European Ground Transportation of Dangerous
Goods). It is the responsibility of the shipper to ensure compliance with these or any other
local requirements. Please consult current regulations and requirements before shipping.
Power Module Considerations:
The power module with the wireless unit contains one “D” size primary lithium-thionyl
chloride battery (Green Power Module, model number 701PGNKF). Each battery contains
approximately 5.0 grams of lithium. Under normal conditions, the battery materials are
self-contained and are not reactive as long as the batteries and the pack integrity are
maintained. Care should be taken to prevent thermal, electrical or mechanical damage.
Contacts should be protected to prevent premature discharge.
Battery hazards remain when cells are discharged.
Power Modules should be stored in a clean and dry area. For maximum Power Module life,
storage temperature should not exceed 30 °C.
v
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00809-0300-4248, Rev AA
Contents
1Section 1: Introduction
Table of Contents
July 2014
1.1 Using this manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Safety messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
1.3 Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
1.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
1.3.2 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
1.3.3 Mechanical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.3.4 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.3.5 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.4 Service support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1.5 Product recycling/disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2Section 2: Configuration
2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Safety messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2.3 Sensor connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4 Bench top configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
2.5 Device network configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
2.5.1 Join to network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
2.5.2 Configure update rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
2.5.3 HART menu tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
2.5.4 Fast Key sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
2.5.5 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
2.6 Remove power module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
3Section 3: Installation
3.1 Safety messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
3.1.1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Table of Contents
3.2 Wireless consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
3.2.1 Power up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
3.2.2 Internal antenna position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
3.3 Field Communicator connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
3.4 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
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3.5 Physical installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
3.5.1 Direct mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
3.5.2 Remote mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
4Section 4: Commissioning
4.1 Safety messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
4.1.1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
4.2 Verify operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
4.2.1 Field Communicator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
4.2.2 Emerson Smart Wireless Gateway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
4.3 AMS
4.4 Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
4.5 Reference information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
™
Wireless Configurator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
5Section 5: Operation and Maintenance
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5.1 Safety messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
5.1.1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
5.2 Power module replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
5.3 LCD screen messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
5.3.1 Startup screen sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
6Section 6: Troubleshooting
6.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
6.2 Safety messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
6.2.1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
AAppendix A: Specifications and Reference Data
A.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
A.1.1 Functional specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
A.1.2 Physical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
A.1.3 Performance specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
A.1.4 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
A.1.5 Ambient temperature effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
A.1.6 Lead wire resistance effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
viii
A.2 Dimensional drawings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
A.3 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
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BAppendix B: Product Certifications
CAppendix C: Mapping for non-DD based Integration with Host
Table of Contents
July 2014
B.1 Approved Manufacturing Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
B.2 European Directive Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
B.3 Ordinary Location Certification from FM Approvals . . . . . . . . . . . . . . . . . . . . . . . .47
Systems
C.1 Mapping of alert messages in the HART command 48 additional status . . . . . .49
C.2 Mapping of device variables index numbers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
Table of Contents
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Section 1 Introduction
1.1 Using this manual
The sections in this manual provide information on installing, operating, and maintaining the
Rosemount 248 Wireless temperature transmitter with WirelessHART
are organized as follows:
Section 2: Configuration provides instruction on commissioning and operating 248
Wireless transmitters. Information on software functions, configuration parameters,
and on line variables is also included.
Section 3: Installation contains mechanical and electrical installation instructions.
Section 4: Commissioning contains techniques for properly commissioning the device.
Section 5: Operation and Maintenance contains operation and maintenance
techniques.
Section 6: Troubleshooting provides troubleshooting techniques for the most common
operating problems.
Section 1: Introduction
July 2014
®
protocol. The sections
Appendix A: Specifications and Reference Data supplies reference and specification
data, as well as ordering information.
Appendix B: Product Certifications contains approval information.
Appendix C: Mapping for non-DD based Integration with Host Systems
Rosemount 248 Wireless Transmitter
Features of the Rosemount 248 Wireless include:
An installation-ready solution that provides a variety of mounting options, transmitter
configurations, and sensors/thermowells
Flexibility to meet your most demanding applications
Wireless output with >99% data reliability delivers rich HART data, protected by
industry leading security
Simple and easy installation practices already used today for robust installations
Refer to the following literatures for a full range of compatible connection heads, sensors, and
thermowells provided by Emerson Process Management.
English Temperature Sensors and Assemblies Product Data Sheet, Volume 1 (document
number 00813-0100-2654)
Temperature Sensors and Accessories (Metric Sensors) Product Data Sheet, Volume 2
(document number 00813-0200-2654)
Introduction
1
Section 1: Introduction
July 2014
1.2 Safety messages
Instructions and procedures in this section may require special precautions to ensure the safety
of the personnel performing the operations. Information that potentially raises safety issues is
indicated by a warning symbol ( ). Please refer to the following safety messages before
performing an operation preceded by this symbol.
1.2.1 Warnings
Failure to follow these installation guidelines could result in death or serious injury.
Make sure only qualified personnel perform the installation.
Explosions could result in death or serious injury.
Before connecting a Field Communicator in an explosive atmosphere, make sure the
instruments are installed in accordance with intrinsically safe or non-incendive field
wiring practices.
Verify that the operating atmosphere of the transmitter is consistent with the
appropriate hazardous locations certifications.
Process leaks could result in death or serious injury.
Do not remove the thermowell while in operation.
Install and tighten thermowells and sensors before applying pressure
Electrical shock could cause death or serious injury.
Avoid contact with the leads and terminals. High voltage that may be present on leads
can cause electrical shock.
This device complies with Part 15 of the FCC Rules. Operation is subject to the
following conditions.
This device may not cause harmful interference.
This device must accept any interference received, including interference that may
cause undesired operations.
This device must be installed to ensure a minimum antenna separation distance of 20
cm from all person.
The Power Module may be replaced in a hazardous area. The Power Module has surface
resistivity greater than one gigaohm and must be properly installed in the wireless device
enclosure. Care must be taken during transportation to and from the point of installation to
prevent electrostatic charge build-up.
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2
Introduction
Reference Manual
00809-0300-4248, Rev AA
1.3 Considerations
1.3.1 General
Electrical temperature sensors such as RTDs and thermocouples produce low-level signals
proportional to their sensed temperature. With simple HART configuration, the Rosemount 248
Wireless converts the low-level sensor signal to a wireless-enabled signal.
1.3.2 Commissioning
The transmitter can be commissioned before or after installation. It may be useful to
commission it on the bench, before installation, to ensure proper operation and to become
familiar with its functionality. When applicable, make sure the instruments are installed in
accordance with intrinsically safe or non-incendive field wiring practices. The device will be
powered whenever the power module is installed. To avoid depleting the Power Module, make
sure it is removed when the device is not in use.
Power up sequence
Section 1: Introduction
July 2014
The Power Module should not be installed on any wireless device until the Smart Wireless
Gateway is installed and functioning properly. This transmitter uses the Green Power Module
(order model number 701PGNKF). Wireless devices should also be powered up in order of
proximity from the Smart Wireless Gateway, beginning with the closest. This will result in a
simpler and faster network installation. Enable Active Advertising on the Gateway to ensure that
new devices join the network faster. For more information, see the Smart Wireless Gateway
Manual (Doc. No. 00809-0200-4420).
Internal antenna position
The internal antenna is designed for multiple mounting orientations. The transmitter should be
mounted according to best practices for your temperature measurement application. The
antenna should be approximately 3 ft (1 m) from any large structure or building to allow clear
communication to other devices.
Network design best practices
When mounting the device, recommended practices should be considered to achieve the best
wireless performance. See “Mounting” on page 23 for more information on recommended
practices.
Field Communicator connections
The Power Module needs to be installed in the device for the Field Communicator to interface
with the Rosemount 248 Wireless Temperature Transmitter. The Field Communicator
connections are located on the Power Module. To communicate to the transmitter, connect the
Field Communicator to the COMM port connections on the Power Module. This transmitter uses
the Green Power Module; please order model number 701PGNKF. Field communication with
this device requires a HART-based Field Communicator using the correct Rosemount 248
Wireless DD. The Power Module is keyed and can only be inserted in one orientation. Refer to
Figure 3-1 for instructions on connecting the Field Communicator to the 248.
Introduction
3
Section 1: Introduction
July 2014
1.3.3 Mechanical
Location
When choosing an installation location and position, take into account the need for access to
the mesh network, access to the transmitter and to the power module compartment for ease
power module replacement.
Electronics cover
The electronics cover is tightened so that polymer contacts polymer. When removing the
electronics cover, ensure that there is no damage done to the o-ring. If damaged replace before
reattaching cover, ensuring polymer contacts polymer (i.e. no o-ring visible).
1.3.4 Electrical
Power Module
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The Rosemount 248 Wireless Temperature transmitter is self-powered. The Power Module
contains a primary lithium-thionyl chloride battery (Green Power Module, model number
701PGNKF). Each battery contains approximately 5 grams of lithium. Under normal conditions,
the battery materials are self-contained and are not reactive as long as the battery and the
Power Module are maintained. Care should be taken to prevent thermal, electrical, or
mechanical damage. Contacts should be protected to prevent premature discharge.
Use caution when handling the power module, it may be damaged if dropped from heights in
excess of 20 feet.
Battery hazards remain when cells are discharged.
Power Modules should be stored in a clean and dry area. For maximum Power Module life,
storage temperature should not exceed 30 °C.
Sensor
Make sensor connections with the threaded 1/2-inch. NPT connection sensor adapter.
1.3.5 Environmental
Verify that the operating atmosphere of the transmitter is consistent with the appropriate
hazardous locations certifications.
Temperature effects
The transmitter will operate within specifications for ambient temperatures between –40 and
185 °F (–40 and 85 °C). Heat from the process is transferred from the thermowell to the
transmitter housing. If the expected process temperature is near or beyond specification limits,
consider the use of additional thermowell and extension, or remote mounting the transmitter
to thermally isolate it from the process.
4
Introduction
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Temperature limits
Operating limit Storage limit
–40 to 185 °F –40 to 185 °F
–40 to 85 °C –40 to 85 °C
1.4 Service support
To expedite the return process outside of the United States, contact the nearest Emerson
Process Management representative.
Within the United States, call the Emerson Process Management Instrument and Valves
Response Center using the 1-800-654-RSMT (7768) toll-free number. This center, available 24
hours a day, will assist you with any needed information or materials.
The center will ask for the following information:
Product model
Serial numbers
The last process material to which the product was exposed
Section 1: Introduction
July 2014
The center will provide:
A Return Material Authorization (RMA) number
Instructions and procedures that are necessary to return goods that were exposed to
hazardous substances
Individuals who handle products exposed to a hazardous substance can avoid injury if they
are informed of and understand the hazard. If the product being returned was exposed to a
hazardous substance as defined by OSHA, a copy of the required Material Safety Data Sheet
(MSDS) for each hazardous substance identified must be included with the returned goods.
Note
If the device has been exposed to a hazardous substance, a Material Safety Data Sheet (MSDS)
must be included with the returned materials. An MSDS is required by law to be available to
people exposed to specific hazardous substances.
Introduction
5
Section 1: Introduction
NOTICE
July 2014
Shipping considerations for wireless products (Lithium Batteries: Green Power
Module, model number 701PGNKF):
The unit was shipped to you without the Power Module installed. Please remove the Power
Module prior to shipping the unit.
Each power module contains a primary lithium-thionyl chloride battery. Primary lithium
batteries are regulated in transportation by the U. S. Department of Transportation, and
are also covered by IATA (International Air Transport Association), ICAO (International Civil
Aviation Organization), and ARD (European Ground Transportation of Dangerous Goods). It
is the responsibility of the shipper to ensure compliance with these or any other local
requirements. Please consult current regulations and requirements before shipping.
1.5 Product recycling/disposal
Recycling of equipment and packaging should be taken into consideration and disposed of in
accordance with local and national legislation/regulations.
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Introduction
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Section 2 Configuration
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 7
Safety messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 7
Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 8
Sensor connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 9
Bench top configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 12
Device network configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 14
HART menu tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 15
2.1 Overview
This section contains information on configuration and verification that should be performed
prior to installation.
Section 2: Configuration
July 2014
Field Communicator and AMS instructions are given to perform configuration functions. For
convenience, Field Communicator fast key sequences are labeled “Fast Keys” for each software
function below the appropriate headings.
Sensor Input Trim example
Fast Key sequence
1, 2, 3, etc.
2.2 Safety messages
Instructions and procedures in this section may require special precautions to ensure the safety
of the personnel performing the operations. Information that potentially raises safety issues is
indicated by a warning symbol ( ). Please refer to the following safety messages before
performing an operation preceded by this symbol.
Electrical grounds are indicated on drawings by a ground symbol ( ). Always follow proper
grounding practices.
Configuration
7
Section 2: Configuration
July 2014
2.2.1 Warnings
Failure to follow these installation guidelines could result in death or
serious injury.
Make sure only qualified personnel perform the installation.
Explosions could result in death or serious injury.
Before connecting a Field Communicator in an explosive atmosphere, make sure the
instruments are installed in accordance with intrinsically safe or non-incendive field
wiring practices.
Verify that the operating atmosphere of the transmitter is consistent with the
appropriate hazardous locations certifications.
Process leaks could result in death or serious injury.
Do not remove the thermowell while in operation.
Install and tighten thermowells and sensors before applying pressure
Electrical shock could cause death or serious injury.
Avoid contact with the leads and terminals. High voltage that may be present on leads
can cause electrical shock.
This device complies with Part 15 of the FCC Rules. Operation is subject to the
following conditions:
This device may not cause harmful interference.
This device must accept any interference received, including interference that may
cause undesired operation.
This device must be installed to ensure a minimum antenna separation distance of 20
cm from all persons.
The Power Module may be replaced in a hazardous area. The Power Module has
surface resistivity greater than one gigaohm and must be properly installed in the
wireless device enclosure. Care must be taken during transportation to and from the
point of installation to prevent electrostatic charge build-up.
Reference Manual
00809-0300-4248, Rev AA
8
Configuration
Reference Manual
00809-0300-4248, Rev AA
2.3 Sensor connections
The 248 Wireless is compatible with a number of RTD and thermocouple sensor types.
Figure 2-1 shows the correct input connections to the sensor terminals on the transmitter. To
ensure a proper sensor connection, anchor the sensor lead wires into the appropriate
compression terminals and tighten the screws.
Thermocouple or Millivolts inputs
The thermocouple can be connected directly to the transmitter. Use appropriate thermocouple
extension wire if mounting the transmitter remotely from the sensor.
RTD or Ohm inputs
The transmitters will accept a variety of RTD or ohmic configurations, including 2-wire, 3-wire or
4-wire connections. If the transmitter is mounted remotely from a 3-wire or 4-wire RTD, it will
operate within specifications, without recalibration, for lead wire resistances of up to 5 ohms
per lead (equivalent to 500 feet of 20 AWG wire). In this case, the leads between the RTD and
transmitter should be shielded. If using a 2-wire connection, both RTD leads are in series with
the sensor element, so significant errors can occur if the lead lengths exceed three feet of 20
AWG wire (approximately 0.05 C/ft.). For longer runs, attach a third or fourth lead to achieve a
3-wire or 4-wire connection as described above.
Section 2: Configuration
July 2014
Effect-RTD input
Since the lead wires are part of the RTD circuit, the lead wire resistance needs to be
compensated for to achieve the best accuracy. This becomes especially critical in applications
where long sensor and/or lead wires are used. There are three lead wire configurations
commonly available. In a two-wire configuration there can be no compensation for lead wire
resistance since the lead wires are in series with the element and appear to the transmitter as
part of the sensor's resistance causing inherent accuracy degradation. In a three-wire
configuration, compensation is accomplished using the third wire with the assumption that it
will be the same resistance as the other two wires and the same compensation is applied to all
three wires. A four-wire design is ideal because the lead wire resistance is inconsequential to the
measurement. It uses a measurement technique where a very small constant current of about
150 micro amps is applied to the sensor through two leads and the voltage developed across
the sensor is measured over the other two wires with a high-impedance and high resolution
measuring circuit. In accordance with Ohm's Law, the high impedance virtually eliminates any
current flow in the voltage measurement leads and therefore the resistance of the leads is not a
factor.
Table 2-1. Examples of Approximate Basic Error
Sensor input Approximate basic error
4-wire RTD Negligible
3-wire RTD Error in reading is equivalent to unbalanced lead wire resistance
2-wire RTD Error in reading is equivalent to total lead wire resistance
(1) Independent of lead wire resistance up to 5 per lead.
(2) Unbalanced lead wire resistance is the maximum resistance differences between any two leads.
(1)
(2)
Configuration
9
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