Rosemount 248 Temperature Transmitter Owner's manual

00809-0100-4825, Rev DB

December 2019

Rosemount

™

248 Temperature Transmitter

Reference Manual

NOTICE

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.

The United States has two toll-free assistance numbers and one international number.

Customer Central

1 800 999 9307 (7:00 am to 7:00 pm CST)

National Response Center

1 800 654 7768 (24 hours a day) Equipment service needs

International

1 952 906 8888

CAUTION

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 an Emerson Sales Representative.

WARNING

Failure to follow these installation guidelines could result in death or serious injury.

Ensure only qualified personnel perform the installation.

Explosions could result in death or serious injury.

Do not remove the housing covers in explosive atmospheres when the circuit is live.

Before connecting a handheld 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.

All connection head covers must be fully engaged to meet explosion-proof requirements.

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.

Use extreme caution when making contact with the leads and terminals.

Physical access

Unauthorized personnel may potentially cause significant damage to and/or misconfiguration of end users’ equipment. This could

be intentional or unintentional and needs to be protected against.

Physical security is an important part of any security program and fundamental to protecting your system. Restrict physical access

by unauthorized personnel to protect end users’ assets. This is true for all systems used within the facility.

2

Contents

Chapter 1 Introduction.................................................................................................................. 5

1.1 Using this Manual............................................................................................................................. 5

1.2 Transmitter overview....................................................................................................................... 5

1.3 Product recycling/disposal................................................................................................................7

Chapter 2 Installation.....................................................................................................................9

2.1 Safety messages...............................................................................................................................9

2.2 Confirm HART revision capability......................................................................................................9

2.3 Switch HART revision mode............................................................................................................10

2.4 Considerations............................................................................................................................... 10

2.5 Mounting....................................................................................................................................... 12

2.6 Installing the transmitter................................................................................................................13

2.7 Multichannel installations...............................................................................................................17

2.8 Set the switches............................................................................................................................. 18

2.9 Wiring............................................................................................................................................ 19

2.10 Power supply................................................................................................................................23

Chapter 3 Configuration...............................................................................................................27

3.1 Safety messages.............................................................................................................................27

3.2 Commissioning.............................................................................................................................. 27

3.3 AMS Device Manager......................................................................................................................28

3.4 Field Communicator.......................................................................................................................29

3.5 Multidrop communication..............................................................................................................40

3.6 Rosemount 248 Configuration Interface specifications.................................................................. 41

Chapter 4 Operation and maintenance.........................................................................................43

4.1 Safety messages.............................................................................................................................43

4.2 Calibration......................................................................................................................................43

4.3 Transmitter-Sensor Natching......................................................................................................... 45

4.4 Switching HART Revision................................................................................................................ 47

4.5 Hardware Maintenance.................................................................................................................. 48

4.6 Diagnostic messages......................................................................................................................48

Chapter 5 Safety Instrumented Systems (SIS) requirements......................................................... 53

5.1 SIS certification...............................................................................................................................53

5.2 Identify safety certification............................................................................................................. 53

5.3 Installation..................................................................................................................................... 53

5.4 Configuration................................................................................................................................. 54

5.5 Operation and maintenance...........................................................................................................54

5.6 Specifications................................................................................................................................. 56

Contents

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Rosemount 248 iii

Appendix A Reference data............................................................................................................. 57

A.1 Product certifications..................................................................................................................... 57

A.2 Ordering Information, Specifications, and Drawings...................................................................... 57

Contents

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iv Rosemount 248

1 Introduction

1.1 Using this Manual

This manual is designed to assist in the installation, operation, and maintenance of the

Rosemount

™

248 Temperature Transmitter.

Introduction

• Manual overview

• Transmitter overview

Installation

• Things to consider

• How to mount the transmitter

• How to install the transmitter

• How to set the switches to ensure proper use

• How to wire and power up the transmitter

Configuration

• Commissioning to transmitter

• How to use the Field Communicator to configure the transmitter

Operation and maintenance

• Calibrate the transmitter

• Explanation of hardware maintenance and diagnostic messages

• How to return the transmitter

Reference data

• Product certifications/Hazardous locations certifications

• Specifications

• Dimensional drawings

• Ordering information

1.2 Transmitter overview

Features of the Rosemount 248 include:

• Acceptance of inputs from a wide variety of RTD and thermocouple sensors

• Configuration using HART

®

protocol

• Electronics encapsulated in epoxy and enclosed in a plastic housing, making the

transmitter extremely durable and ensuring long-term reliability

Introduction

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Rosemount 248 5

• IEC 61508:2010 safety certification

• A compact size and multiple housing options that allow mounting flexibility in the field

• Improve measurement accuracy with Transmitter-Sensor matching.

Refer to the following literature for a full range of compatible connection heads, sensors,

and thermowells provided by Emerson:

• Rosemount 214C Temperature Sensors Product Data Sheet

• Rosemount Volume 1 Temperature Sensors and Accessories (English) Product Data

Sheet

• Rosemount DIN-Style Temperature Sensors and Thermowells (Metric) Product Data

Sheet

Table 1-1 and Table 1-2 summarize changes in the Rosemount 248 Head Mount and Rail

Mount HART device revisions, respectively.

Table 1-1: Head Mount HART Revisions

Identify device Field device driver Review

instructions

Software

release date

NAMUR

software

revision

NAMUR

hardware

revision

(1)

HART

universal

revision

(2)

Device

revision

Manual document

number

Jun 2019 1.0.1. 1.0.2 7 7.4.11

(3)

00809-0100-4825

5 5.2.11

(3)

Dec 2005 N/A N/A 5 5.2.2.

(1) NAMUR Software Revision is located in the hardware tag of the device. HART Software Revision

can be read using a HART capable configuration tool.

(2) Device Driver file names use Device and DD Revision, (e.g., 10_07. HART Protocol) is designed to

enable legacy driver revisions to continue to communicate with new HART devices. To access this

functionality, the new device driver must be downloaded. It is recommended to download the

new device driver to ensure new functionality.

(3) HART 5 and 7 Selectable, CVD sensor matching.

Table 1-2: Rail Mount HART Revisions

Identify device Field device driver Review

instructions

Software

release date

NAMUR

software

revision

NAMUR

hardware

revision

(1)

HART

universal

revision

(2)

Device

revision

Manual document

number

Mar 2005 N/A N/A 5 5.2.1. 00809-0100-4825

(1) NAMUR Software Revision is located in the hardware tag of the device. HART Software Revision

can be read using a HART capable configuration tool.

(2) Device Driver file names use Device and DD Revision, (e.g., 10_07. HART) Protocol is designed to

enable legacy driver revisions to continue to communicate with new HART devices. To access this

functionality, the new device driver must be downloaded. It is recommended to download the

new device driver to ensure new functionality.

Introduction

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6 Rosemount 248

1.3 Product recycling/disposal

Recycling of equipment and packaging should be taken into consideration and disposed of

in accordance with local and national legislation/regulations.

Introduction

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Rosemount 248 7

Introduction

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8 Rosemount 248

2 Installation

2.1 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.

WARNING

Failure to follow these installation guidelines could result in death or serious injury.

Ensure only qualified personnel perform the installation.

Explosions could result in death or serious injury.

Do not remove the housing covers in explosive atmospheres when the circuit is live.

Before connecting a handheld 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.

All connection head covers must be fully engaged to meet explosion-proof

requirements.

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.

Use extreme caution when making contact with the leads and terminals.

2.2 Confirm HART revision capability

If using HART

®

based control or asset management systems, confirm the HART Protocol

capability of those systems prior to transmitter installation. Not all systems are capable of

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Rosemount 248 9

communicating with HART Revision 7. This transmitter can be configured for either HART

Revision 5 or Revision 7.

2.3 Switch HART revision mode

If the HART Protocol configuration tool is not capable of communicating with HART

Revision 7, the transmitter will load a generic menu with limited capability. The following

procedures will switch the HART Revision mode from the generic menu:

Procedure

Select Manual Setup → Device Information → Identification → Message.

a) To change to HART Revision 5, enter HART5 in the Message field.

b) To change to HART Revision 7, enter HART7 in the Message field.

2.4 Considerations

2.4.1 General

Electrical temperature sensors, such as RTDs and thermocouples, produce low-level

signals proportional to the sensed temperature. The Rosemount

™

248 Temperature

Transmitter converts the low-level sensor signal to a HART 4–20 mA dc signal that is

relatively insensitive to lead length and electrical noise. This current signal is transmitted

to the control room through two wires.

2.4.2

Commissioning

The transmitter may be commissioned before or after installation. It can be useful to

commission it on the bench, before installation, to ensure proper operation and to

become familiar with its functionality. The instruments in the loop should be installed

according to the intrinsically safe or non-incendive field wiring practices before connecting

a Field Communicator in an explosive atmosphere. For more information, see

Commissioning.

2.4.3

Mechanical

Location

When choosing an installation location, take into account access to the transmitter.

Special mounting

Special hardware is available for mounting the transmitter to a DIN rail.

2.4.4

Electrical

Proper electrical installation is necessary to prevent errors from sensor lead resistance and

electrical noise. For best results, shielded cable should be used in electrically noisy

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10 Rosemount 248

environments. A resistance between 250 and 1100 ohms must be present in the loop for

communication with a Field Communicator.

Make wiring connections through the cable entry in the side of the connection head being

sure to provide adequate clearance for cover removal.

2.4.5 Environmental

The transmitter electronics module is permanently sealed within the housing, to resist

moisture and corrosive damage. Verify that the operating atmosphere of the transmitter

is consistent with the appropriate hazardous locations certifications.

Temperature effects

The transmitter operates within specifications for ambient temperatures between –40 and

185 °F (–40 and 85 °C)

(1)

. Process heat from the process is transferred from the thermowell

to the transmitter housing so if the expected process temperature is near or above

specification limits, consider using an additional thermowell lagging, and extension

nipple, or a remote mounting configuration to isolate the transmitter from the process.

Note

Extended ranges available with BR5 and BR6 option codes for extending the lower ambient

temperature limit to –58 and –76 °F (–50 and –60 °C), respectively.

Figure 2-1 provides an example of the relationship between transmitter housing

temperature rise and extension length.

Figure 2-1: Connection Head Temperature Rise vs. Extension Length

Example

The transmitter specification limit is 185 °F (85 °C). If the ambient temperature is 131 °F

(55 °C) and the process temperature to be measured is 1472 °F (800 °C), the maximum

permissible connection head temperature rise is the transmitter specification limit minus

the ambient temperature (moves 185 to 131 °F [85 to 55 °C]), or 86 °F (30 °C). In this case,

an extension of 3.93-in. (100 mm) meets this requirement, but 4.92-in. (125 mm)

provides a margin of 46.4 °F (8 °C), reducing any temperature effects in the transmitter.

(1)

Extended ranges available with BR5 and BR6 option codes.

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Rosemount 248 11

2.4.6 Installation Flowchart

Figure 2-2: Installation Flowchart

2.5 Mounting

Mount the transmitter at a high point in the conduit run to prevent moisture from draining

into the transmitter housing.

The Rosemount 248R installs directly to a wall or to a DIN rail.

The Rosemount 248H installs:

• In a connection head or universal head mounted directly on a sensor assembly

• Apart from a sensor assembly using a universal head

• To a DIN rail using an optional mounting clip

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12 Rosemount 248

2.5.1 Mounting a Rosemount 248H to a DIN rail

Procedure

• To attach a head mount transmitter to a DIN rail, assemble the appropriate rail

mounting kit (part number 00248-1601-0001) .

Figure 2-3: Assembling Rail Clip Hardware to a Rosemount 248

C

B

A

A. Mounting hardware

B. Transmitter

C. Rail clip

2.6 Installing the transmitter

The Rosemount 248 can be ordered assembled to a sensor and thermowell or as a stand-

alone unit. If ordered without the sensor assembly, use the following guidelines when

installing the transmitter with an integral sensor assembly.

2.6.1

Typical European and Asia Pacific installation

Head mount transmitter with DIN plate style sensor

Procedure

1. Attach the thermowell to the pipe or process container wall then install and tighten

the thermowell before applying process pressure.

2. Assemble the transmitter to the sensor. Push the transmitter mounting screws

through the sensor mounting plate and insert the snap rings (optional) into the

transmitter mounting screw groove.

3. Wire the sensor to the transmitter (see Sensor connections).

4. Insert the transmitter-sensor assembly into the connection head. Thread the

transmitter mounting screw into the connection head mounting holes and

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Rosemount 248 13

assemble the extension to the connection head then insert the assembly into the

thermowell.

5. Slip the shielded cable though the cable gland.

6. Attach a cable gland into the shielded cable.

7. Insert the shielded cable leads into the connection head through the cable entry

then connect and tighten the cable gland.

8. Connect the shielded power cable leads to the transmitter power terminals making

sure to avoid contact with sensor leads and sensor connections.

9. Install and tighten the connection head cover making sure the enclosure covers are

fully engaged to meet explosion-proof requirements.

Figure 2-4: European and Asia Pacific installation diagram

A. Rosemount 248 transmitter

B. Connection head

C. Thermowell

D. Transmitter mounting screws

E. Integral mount sensor with flying leads

F. Extension

2.6.2

Typical North and South American installation

Head mount transmitter with threaded sensor

Procedure

1. Attach the thermowell to the pipe or process container wall then install and tighten

thermowells before applying process pressure.

2. Attach necessary extension nipples and adapters to the thermowell making sure to

seal the nipple and adapter threads with silicone tape.

3. Twist the sensor into the thermowell and install drain seals, if required, for severe

environments or to satisfy code requirements.

4. Pull the sensor wiring leads through the universal head and transmitter. Mount the

transmitter in the universal head by threading the transmitter mounting screws into

the universal head mounting holes.

5. Mount the transmitter-sensor assembly into the thermowell, sealing the adapter

threads with silicone tape.

6. Install conduit for field wiring to the conduit entry of the universal head. Seal the

conduit threads with silicone tape.

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14 Rosemount 248

7. Pull the field wiring leads through the conduit into the universal head. Attach the

sensor and power leads to the transmitter. Avoid contact with other terminals.

8. Install and tighten the universal head cover. Enclosure covers must be fully engaged

to meet explosion-proof requirements.

Figure 2-5: North and South American Installation

A. Threaded thermowell

B. Threaded style sensor

C. Standard extension

D. Universal head

E. Conduit entry

Rail mount transmitter with integral mount sensor

The least complicated assembly uses:

• an integral mount sensor with terminal block

• an integral DIN style connection head

• a standard extension

• a threaded thermowell

Refer to the appropriate Product Data Sheet regarding Rosemount temperature elements

for complete sensor and mounting accessory information.

To complete the assembly:

Procedure

1. Attach the transmitter to a suitable rail or panel.

2. Attach the thermowell to the pipe or process container wall. Install and tighten the

thermowell before applying pressure.

3. Attach the sensor to the connection head and mount the entire assembly to the

thermowell.

4. Attach sufficient lengths of sensor lead wire to the sensor terminal block.

5. Attach and tighten the connection head cover. Enclosure covers must be fully

engaged to meet explosion-proof requirements.

6. Run sensor lead wires from the sensor assembly to the transmitter.

7. Attach the sensor and power leads to the transmitter. Avoid contact with leads and

terminals.

Installation

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Rosemount 248 15

Figure 2-6: Typical Rail Mount Transmitter Mounting Configuration Using

Integral Mount Sensor and Assembly

A. Rail mount transmitter

B. Sensor leads with cable gland

C. Integral mount sensor with terminal block

D. Connection head

E. Standard extension

F. Threaded thermowell

Rail mount transmitter with threaded sensor

The least complicated assembly uses:

• a threaded sensor with flying heads

• a threaded sensor connection head

• a union and nipple extension assembly

• a threaded thermowell

Refer to the appropriate Product Data Sheet regarding Rosemount temperature elements

for complete sensor and mounting accessory information.

To complete the assembly:

Procedure

1. Attach the transmitter to a suitable rail or panel.

2. Attach the thermowell to the pipe or process container wall. Install and tighten the

thermowell before applying pressure.

3. Attach necessary extension nipples and adapters. Seal the nipple and adapter

threads with silicone tape.

4. Twist the sensor into the thermowell. Install drain seals if required for severe

environments or to satisfy code requirements.

5. Screw the connection head to the sensor.

6. Attach the sensor lead wires to the connection head terminals.

7. Attach additional sensor lead wires from the connection head to the transmitter.

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16 Rosemount 248

8. Attach and tighten the connection head cover. Enclosure covers must be fully

engaged to meet explosion-proof requirements.

9. Attach the sensor and power leads to the transmitter. Avoid contact with leads and

terminals.

Figure 2-7: Typical Rail Mount Transmitter Mounting Configuration Using

Threaded Style Sensor and Assembly

A. Rail mount transmitter

B. Threaded sensor connection head

C. Threaded style sensor

D. Standard extension

E. Threaded thermowell

2.7 Multichannel installations

Several transmitters can be connected to a single master power supply, as shown in Figure

2-8. In this case, the system may be grounded only at the negative power supply terminal.

In multichannel installations, where several transmitters are dependent on one power

supply and the loss of all transmitters would cause operational problems, consider an

uninterrupted power supply or a back-up battery. The diodes shown in Figure 2-8 prevent

unwanted charging or discharging of the back-up battery.

Installation

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Rosemount 248 17

Figure 2-8: Multichannel Installations

A. Transmitter 1

B. Transmitter 2

C. R

Lead

D. Readout or controller no. 1

E. Readout or controller no. 2

F. Backup battery

G. Power supply (dc)

H. To additional transmitters

2.8 Set the switches

2.8.1 Failure mode

Each transmitter continuously monitors its performance during normal operation with an

automatic diagnostic routine of continuous timed series of checks. If an input sensor

failure or a transmitter electronics failure is detected, the transmitter outputs the low or

high alarm, depending on the failure mode configuration. For sensor temperature outside

of range limits:

Standard saturation levels:

• 3.90 mA on the low end

• 20.5 mA on the high end

NAMUR compliant saturation levels:

• 3.80 mA on the low end

• 20.5 mA on the high end

These values are also custom configurable by the factory or using the Field Communicator

or AMS Device Manager. See for instructions on how to change the alarm and saturation

levels with the Field Communicator.

Note

Microprocessor failures cause high alarm regardless of alarm direction (high or low)

choice.

The values the transmitter drives its output in failure mode depend on if it is configured to

standard, NAMUR-compliant, or custom operation.

Installation

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18 Rosemount 248

2.9 Wiring

All power to the transmitter is supplied over the signal wiring. Ordinary copper wire of

sufficient size should be used to ensure the voltage across the transmitter power terminals

does not drop below 12.0 Vdc. Verify that the operating atmosphere of the transmitter is

consistent with the appropriate hazardous locations certifications. Always use extreme

caution when making contact with the leads and terminals.

If the sensor is installed in a high-voltage environment and a fault condition or installation

error occurs, the sensor leads and transmitter terminals could carry lethal voltages. Use

extreme caution when making contact with the leads and terminals.

CAUTION

Do not apply high voltage (e.g., ac line voltage) to the transmitter terminals since high

voltage can damage the unit. (Sensor and transmitter power terminals are rated up to

42.4 Vdc.) Use extreme caution when making contact with the leads and terminals.

For multichannel installations, see Multichannel installations. The transmitters accept

inputs from a variety of RTD and thermocouple types. Refer to Figure 2-10 when making

sensor connections.

Use the following steps to wire the transmitter:

Procedure

1. Remove the terminal block cover (if applicable).

2. Connect the positive power lead to the “+” terminal. Connect the negative power

lead to the “–” terminal (see Figure 2-9). Use extreme caution when making contact

with the leads and terminals.

3. Tighten the terminal screws.

4. Reattach and tighten the cover (if applicable). All connection head covers must be

fully engaged to meet explosion-proof requirements.

5. Apply power (see Power supply).

Installation

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Rosemount 248 19

Figure 2-9: Rosemount 248 wiring

Power, communication, and sensor

terminals

Connecting a communicator to a transmitter loop

A. Field communicator

B. Power supply

C. 250 V ≤ R

L

≤ 1100 V

D. Recorder (optional)

E. Ammeter (optional)

Note

Signal loop may be grounded at any single point or left ungrounded.

Note

A Field Communicator may be connected at any termination point in the signal

loop. The signal loop must have between 250 and 1100 ohms load for

communications.

2.9.1

Sensor connections

The Rosemount 248 is compatible with a number of RTD and thermocouple sensor types.

Figure 2-10 shows the correct input connections to the sensor terminals on the

transmitter. To ensure proper sensor connection, anchor the sensor lead wires to the

appropriate compression terminals and tighten the screws. Use extreme caution when

making contact with the leads and terminals.

Installation

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20 Rosemount 248

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