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How to get value out of HART
Ensure HART is always connected
Topics Covered
Background
Training
Design
Procurement
Integration
Configuration
Factory Acceptance Test (FAT)
Installation
Commissioning
Change Work Practices
Network Maintenance
System Management
Design Procurement Integration Configuration FAT Installation Commissioning Operation
Background
Put HART to good use
1 1
Consumption Gap
Plants are built with intention to use HART
Plants struggle to utilize HART
HART only used for commissioning with the handheld
field communicator
o The control system uses only 4-20 mA signal
Only some plants use HART always connected
o Only some devices use HART always connected
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Digital HART is Not the Same as Analog 4-20 mA
HART does not get designed and procured correctly
Not installed and commissioned correctly
Not integrated and setup properly
Not maintained properly
People don’t get trained
Plant ends up using only handhelds or laptop with HART
modem, missing out on the smart always connected
capabilities
If you will only use a handheld you need not worry about
most of this…
HART Training
Competency is a critical success factor
2 2
HART Training Required
There are many misconceptions around HART
o The reason why in the end HART is underutilized
Use consultants, EPC contractors, and subcontractors
trained in HART
Train plant personnel on HART to ensure continuity
o If not HART will fall into disuse
Get trained on HART
250 ohm Filter
Line Conditioner Capacitance
Noise
600 ohm Master conflict
HART7
DD file Report by Exception
HART Design
Design for digital, not just analog
3 3
System HART Pass-Through
New systems
Make sure analog input and
analog output cards support
HART communication
Compliant with HCF_SPEC-
054
HART pass-through across the
higher level network
Existing control systems not
supporting HART
Install wireless adapters on
selected instruments
Plant-wide wireless gateway
infrastructure
3.1.1
HART Cable Selection
Individually shielded twisted pair cable o Single pair or multi-pair
Minimum conductor size: o 0.2 mm2 (#24 AWG) for cable runs less than 1.5km
o 0.5 mm2 (#20 AWG) for longer distances
Compliant to the HCF_SPEC-054 specification
Polyethylene (PE) insulation is preferred o Lower capacitance than PVC insulation
o More stable, will not increase as much over time
Low capacitance good-quality cable o Mutual capacitance of 60 nF/km is available
Additional cable requirements may apply depending on the hazardous area classification and local regulations etc.
Similar to FF and other digital
communication
3.1.2
###make sure every
slide has an image
Loop Resistance
HART loop resistance max 600 ohm
o Distance limitation on the wires
250 ohm resistor not required for valve positioner
Calculate the voltage drop to ensure I/O card voltage is
sufficient for all the loads in the loop:
o Transmitter, positioner, indicator, signal conditioner, wireless
adapter, filter, line conditioner, wire resistance
Each type of device and option is different
Replacement device may be different
Loop current may be as high as 23 mA
0
200
400
600
12 14 16 18 VDC
ohm
4-20 mA Operating Area
4-20 mA/HART
Operating Area
3.1.3
Loop Resistance Example
Max loop current is 23 mA
Device requires a minimum of 12 VDC at terminals
Voltage source from the AI card 15 VDC
o Internal 250 ohm shunt resistor
Maximum permitted loop resistance for the cable is (15-
12)/0.023 = 130 ohm
3.1.3
Loop Capacitance
Maximum device capacitance is 5 nF
Cable capacitance limits length
Determine max allowable cable length from the
65 microsecond chart
Use low capacitance cable (PE insulation) with
large conductor cross section
o A full 1.5 km is possible
o PE insulation cable with mutual capacitance
of 60 nF/km is available from many vendors
Additional cable requirements may apply
depending on the hazardous area classification
and local regulations etc.
3.1.4
HART Capacitance 65 us Chart 3.1.4
Loop Capacitance Example
Single device, 5 nF device capacitance, 250 ohm shunt
resistor
Cable Capacitance: 180 nF/km
Conductor Resistance: 49 ohm/km (22 AWG)
1 km
3.1.4
HART Safety Barriers
Intrinsic safety barriers have to be HART compatible
Compliant to the HCF_SPEC-054 specification
All intrinsic safety rules apply
3.1.5
Cabling Route Planning (Cable Trays)
4-20 mA/HART separate from power cables
4-20 mA/HART together with other signal wiring including
fieldbus and other data communication
Signal wiring cross power cables at a right angle
Same as FF and other digital
communication
3.1.6
>30 cm
Shield Connection
Shield must be maintained all the way from the field
device to the control system I/O card
Shield shall not be connected to the device housing
(HCF_SPEC-054 recommendation)
Same as FF and other digital
communication
3.1.7
Do not connect shield+ -
Enclosure Grounding
The device housing shall be connected to ground through
a large cross-section conductor
Same as FF and other digital
communication
3.1.8
Shield Grounding
The shield shall be grounded at the control system I/O
card (HCF_SPEC-054 recommendation)
Same as FF and other digital
communication
3.1.9
Junction Box
Control System Panel
Shield not connected at device
DCS
AI card
R
Transmitter
Filter
HART Communicator+R
HART Input Filters
If system has no low-pass filter in the AI card
Installed near control system AI card
Safe side of safety barrier
May not be suitable for surge controllers
Compliant to the HCF_SPEC-054 specification
3.1.10
HART Output Filters
If system has no filter in AO card
Installed near control system AO card
Safe side of safety barrier
Need sufficient AO card compliance voltage
Some 4-20 mA simulators (loop calibrators) also require a
HART output filter
Compliant to the HCF_SPEC-054 specification
DCS
AO card
Valve Positioner
Filter
HART Communicator
3.1.11
Logic
Solver
DO card
Partial
Stroke
Test
Device
HART
Communicator
Line
ConditionerS
Solenoid
Valve
+
HART Line Conditioners
Used with Partial Stroke Test (PST) device on shutdown
valve
Most logic solvers have no filter in the DO card
Compliant to the HCF_SPEC-054 specification
Similar to FF 3.1.12
HART Compliant Devices
Devices which have not
been registered may not be
fully compliant
Configuration, diagnostics,
auxiliary variables may not
work properly
Nuisance alarms
Specify “Device shall be
HART Registered”
Same as FF and other digital
communication
3.1.13
HART Loop Power Supply
Free from ripple and noise
o Less than 2.2 mV RMS
Old, faulty, or overloaded power supply may be a source
of noise
Compliant to the HCF_SPEC-054 specification
3.1.14
HART Master Conflict
Only two HART masters
Masters must be different class;
o One primary; control system, MUX, wireless adapter,
smart signal conditioner
o One secondary; handheld, laptop with HART modem,
wireless adapter, smart signal conditioner
If two or more masters of the same class are connected
the communication will fail
o Smart signal conditioner will set the analog output < 4
mA or > 20 mA tripping loop
3.2.1
HART Burst Communication
Do not use burst in devices connected to a control system
or multiplexer
o Mostly used for stand-alone smart signal conditioners
Cause diagnostics and auxiliary variable monitoring etc.
to slow down
o Nuisance alarms in the IDM software
3.2.2
Unpolled Address
Use a HART version 7 (HART7) host to ensure all
devices are detected
Version 5 of HART (HART5) only supports address up to
15
Older hosts do not support polling of addresses up to 63
o Will not detect newer devices such as wireless
adapters which use default addresses above 15
3.2.3
HART Command 48 (Diagnostics)
Used for the IDM software alarm management function to
filter the instrument diagnostic alarms from the devices
o Optional in HART5 devices
o Mandatory in HART7 devices
Specify devices shall support command 48
3.3.1
DD Files
DD files are not required to get a 4-20 mA signal
DD files are required for configuration and diagnostics
Without a DD file it is not possible to properly configure a
device to get a correct measurement
Warning: Not all devices come with a DD file
o Configured form a local display or by proprietary
software
o Setting up instrument diagnostic alarm management
filters becomes very challenging
Specify device shall come with DD file
Not all devices
come with DD files
Same as FF and other digital
communication
3.3.2
HART7
HART5 systems cannot support HART7 devices
o Only specify HART7 devices if the system is HART7
compatible
Some devices can be configured to operate as HART5 or
HART7
o Essentially two different devices so have two DD files
HART5 system do
not support HART7 devices
3.3.3
HART Polling
Set the polling time as short (fast) as possible
If the polling time is set longer than a minute;
o Intermittent problems may be missed
o Too short time left for operators to respond
Use polling for diagnostics of 4-20 mA devices
o Triggered burst mode and event notification (“report by
exception”) functions are intended for WirelessHART
Burst communication may interfere with diagnostics
polling
3.3.4
HART Procurement
Buy only tested and registered products
4 4
HART Procurement
A non-compliant component could jeopardize the ability to
utilize HART capabilities
o The analog 4-20 mA signal will work but the smart
features cannot be accessed and the benefits not
reaped
Verify products in bids are tested and registered
HART Integration
Load your DD
5 5
Load DD Files on Control System
Needed to configure diagnostics filtering to display as
human readable text
Some control system may also need an internal system
specific file for each device type
5.1.1
Load DD Files on IDM Software
Without DD file
o The device cannot be made to work correctly
o The 4-20 mA signal may not be correct
Need DD files to commission device
o Configure sensor type and many other settings
o Perform sensor trim and other functions
Some IDM software may also need an internal system
specific file
5.1.2
Load DD Files on Portable Tools
Without DD file
o The device cannot be made to work correctly
o The 4-20 mA signal may not be correct
Need DD files to commission device
o Configure sensor type and many other settings
o Perform sensor trim and other functions
5.1.3
DD File for Correct HART Version
The DD file for HART5 and HART7 version of device is
different
o Buy as HART5 or HART7
o Configure as HART5 or HART7
If the device is configured to operate as HART7 but the
HART5 DD has been loaded, the system cannot access
the device features
5.1.4
HART Configuration
Engineer to avoid alarm flooding
6 6
Avoid Alarm Flooding:
Instrument Diagnostic Alarm Management
If the instrument diagnostic alarm management system is
not configured there will be a flood of nuisance alarms
o System will not be used
ISA108 guidance to being developed
Interim guide:
o http://www.eddl.org/DeviceManagement/Pages/DeviceDiagnostic
s.aspx
Engineer and setup IDM software before start-up
Specify a control system which is able to categorize
instrument diagnostic alarms for command 48
Specify a control system which uses the DD file to display
the possible instrument diagnostic alarms from the device
as plain text
6.1.1
Instrument Diagnostics Alarm
Rationalization
Categorize severity of
diagnostics:
o NAMUR NE107
Identify criticality to the
process for each device tag
Configure system and devices
Same as FF and PROFI
• FAT to verify correct system configuration for alarm management and reports
• Tune device diagnostics to fit the application
• Rewrite maintenance procedures to include the IDM software
• Training
System shall display
diagnostics items as plain
text
6.1.1
Instrument Diagnostic Alarm Routing
Operator Instrument Tech • Failure • Function Check
• Failure • Maintenance Required • Out of Specification
Devices
Nuisance Alarms
Same as FF and PROFI
6.1.1
Valve Tight-Shutoff
If the valve tight-shutoff output current in the control
system is configured to 0 mA, HART communication
stops when valve is closed
o No power to smart valve positioner
o No power to wireless adapter
o Nuisance communication alarms
o No diagnostics
The valve tight-shutoff current setting in the control
system shall be somewhere in the range 3.6-3.8 mA
o Ensures the positioner still performs diagnostics and
devices plus accessories are able to communicate
6.1.2
HART Factory Acceptance Test (FAT)
Test to make sure instrument diagnostics alarm management will work as intended
7 7
Interoperability / Integration Test at FAT
Connect one of each type of device
Open each type of device in the IDM software
o Verifies the DD file has been loaded for each type and
version of the device
o Verifies the device displays correctly
Download a device configuration
o Verify the download is error free
Same as FF and other digital
communication
7.1.1
Instrument Diagnostic Alarm Routing Test at FAT
Simulate instrument diagnostic alarms of different severity
(Advisory, Maintenance, and Failure ) for each device
type
o Verify they are routed to the right person such as
operators or instrument technicians
7.1.2
HART Installation
Wiring
8 8
Poor Installation Jeopardize the Ability
to Utilize HART Capabilities
The HART signal is small, only 1 mA
Poor installation picks up noise
Communication stops updating in the system:
o Diagnostics
o PV, SV, TV, and QV
Nuisance communication alarms
Smart signal conditioner output < 4 or > 20 mA which may
cause a nuisance trip
Same as FF and other digital
communication
Don’t Ground Shield at Device
Do not connect the shield or drain wire to ground in the
device housing
Ground the shield only in a single point, at the power
supply
Only the signal wires are connected at the device
This is the recommendation in the HCF_SPEC-054
specification
o Some plants have other practice
8.1.1 Same as FF and
other digital communication
+ -
Insulate Shield at Device
Do not leave the shield or drain wire “flying” as it may
come in contact with the device housing
Cut the shield inside the device housing
Isolate the drain wire and shield using shrink tube or tape
to make sure it does not come in contact with grounded
metal parts
For armored cable, make sure shield drain wire is not
touching the cable armor
8.1.2 Same as FF and
other digital communication
+ -
Maintain Shield Through Junction Boxes
The shield shall be continuous from system panel,
through junction box, up to the device
o But not connected to the device
Do not ground the shield in the junction box
Do not leave ‘flying’ shield or drain wire as it may touch
other wires or grounded metal parts
If two cables are joined, make sure the junction (splice)
also joins the shields of the two cables
8.1.3 Same as FF and
other digital communication
Junction Box
Control System Panel
Shield not connected at device
Route Signal Cables In Separate Tray
From Power Cables
Do not lay communications signal cable in the same tray
as power cable
Route signal cable and power cable in separate trays
If signal cable and power cable is laid in the same tray,
maintain maximum possible separation, keeping power
cable and signal cables on separate sides of grounded
metal dividing wall
8.1.4 Same as FF and
other digital communication
>30 cm
Min
Observe Cable Minimum Bend Radius
Loop/bend cable too tight will damage the shield
o Reducing noise immunity
Cable minimum bend radius
o Cable type dependent
o For armored cable it can be space taking
Do not turn corners too tight in cable trays
o Use proper cable tray bend, cross, and tee pieces to allow cable
to round corners with wide radius
“Pig tails” must have a sufficiently large radius to not
damage the internal shield
Cable trunking / wire troughs / trays are usually too
narrow to permit looping of the cable
8.1.5 Same as FF and
other digital communication
Ground Device Housing
Without a ground connection the device EMI/RFI
suppression will not work
Make sure the device housing is safety grounded to the
plant structural steel with a low impedance connection to
ensure personnel safety and EMI/RFI suppression
It is particularly important for those devices where surge
protection is used
8.1.6 Same as FF and
other digital communication
Ground Junction Boxes
Make sure the junction box is safety grounded with a low
impedance connection
When using plastic junction boxes and metal cable
glands, these glands must be connected to the safety
ground bar inside the junction box, typically using a metal
plate inside junction box
8.1.7 Same as FF and
other digital communication
Cable lug
Spring washerTooth washer
Don’t Coil Signal Cables And Power
Cables Together
Do not coil signal cables and power cables together
inside the device terminal compartment
o For example, in separately powered devices such as
Coriolis and magnetic flow meters, etc.
Cables shall be:
o Short
o Jacket on
o Shielded
o Separated
8.1.8 Same as FF and
other digital communication
Signal AC Power
AC
Power
Don’t Damage Shield And Conductor Insulation
Cutting Cable Jacket
Do not damage shield and
conductor insulation
Do not use a knife
o It might damage the shield
and conductor insulation
Use a cable jacket/sheath
stripper
Cutting Cable Armor
Do not use a hacksaw
o It might damage the inner
jacket, shield, and
conductor insulation
For tube armor use a
pipe/tubing cutter
For SWA use a wire cutter to
cut strand by strand
8.1.9 Same as FF and
other digital communication
split into two slides
Don’t Strip-Off More Than Necessary
Maintain shield and jacket as far as possible, close to the
connection terminals
Do not remove shield or jacket for cable running in
cabinet or junction box
o Bare shields (and drain wire) of different cables will
touch and may cause ground loops
Do not untwist the twisted pair
8.1.10 Same as FF and
other digital communication
Ground Overall Shield For Multi-pair
Cable
The overall shield shall be grounded in the power supply-
end
Do not leave overall shield floating
Make sure overall shield does not touch any of the
individual pair shields
8.1.11 Same as FF and
other digital communication
Overall
Shield
Control
System Panel
Ground The Cable Armor
Do not leave the cable armor floating
The metal cable gland must make contact with
the amour of the cable at the device and in the
junction box
If plastic cable glands are used at the junction
box, or the junction box is plastic, the cable
armor shall be grounded to safety ground bar
Ground the armor in multiple points:
o Before cable enters marshalling cabinet
o In cable tray
o And in the field junction box
8.1.12 Same as FF and
other digital communication
Armor
Other Good Installation Practices
Do not pull cable with too much force
Make sure cable glands are tight
Seal unused conduit entries
Use correct size ferrule/fork and tool
Do not cram wires in device terminal compartment
Do not over/under-tighten terminal screws
Make sure covers are tight
Do not tighten cable-tie too much
Label wires
Observe polarity
8.1.13 Same as for any cables
HART Commissioning
Digital loop check
9 9
HART Communication Check at Loop
Check (Loop Test)
Also verify the HART communication
o Loop calibrator with HART communication capability
o Handheld field communicator
Communicate with the device to ensure communication is
error free
o Monitor the 4 dynamic variables (PV, SV, TV, and QV)
for some time
Confirms the design and installation is done correctly, so
digital communication will be reliable
Similar to FF and other digital
communication
9.1.1
In addition to traditional 5-
point loop check
Digital Integration Verification at Loop
Check
Open up each device in the IDM software
Confirms:
o Communication is enabled
o Communication is working from the system end
o The DD file matches the device type and version
Open the diagnostics page to see if any problem
o Incorrectly wired temperature sensor
o Valve supply air
o Flow meter auxiliary power
Same as FF and other digital
communication
9.1.2
what about reconciling device
configuration? Ranges, units…
Change Work Practices for HART
Getting into the habit of using the IDM software as part of the daily routine
10 10
Instrument Technician Culture Change
Review instrument diagnostic alarms
o Instrument technicians must review the instrument
diagnostic alarm summary and log every day
Spend time on devices which need attention
Check the software first
o When operations say a device is not working,
instrument technicians must check the software first,
before going to the field to take a look
Avoid unnecessary field visits
Rewriting Standard Operating Procedures (SOPs)
o Rewrite work procedures to include IDM software
Inspection, replacement, calibration and other tasks
10.1.1
10.1.2
10.1.3
split into 3 slides
HART Network Maintenance
Maintain installation in good condition to ensure the HART communication continues to work error free
11 11
Safety Instrumented Systems (SIS) Warning
If device diagnostics is used to claim safety credit, the
digital HART communication must maintained functional
Any communication issues must be resolved immediately
so the always connected diagnostics monitoring remains
functional
If the device is replaced;
o The new device must have the same or better
diagnostics
o Must be digitally integrated
.
Troubleshoot – Don’t Disable
If nuisance communication alarms appear personnel will
disable HART
o Only analog 4-20 mA remains
Troubleshooting should instead be done to bring HART
communication back alive
HART Issues Develop Over Time
Somebody ground cable shield
Inadvertent contact between shield and ground
High loop resistance due to corroded terminals
Added series devices like a wireless adapter
Device replaced with non-HART device
New source of noise
Moisture in device compartment or field junction box
Loose connections due to vibration
High capacitance in aging cable or stray capacitance
Device replaced with wrong HART protocol version
Replacement device not configured correctly
Additional master connected causing master conflict
Shield damaged
Shield continuity compromised
Housing ground disconnected
Field junction box ground corroded
Similar to FF and other digital
communication
Monitor HART Network Health
Periodically check HART communication Packet Error
Rate (PER) to detect deteriorating communication before
alarms appear
o Built-in control system communication diagnostics
o External HART analyzer software with HART modem
Same as FF and other digital
communication
11.1.1
Maintain Installation Integrity
Technicians must be familiar with the additional
requirements of digital HART or mistakes will happen:
o Connecting shield to the ground screw on the device
o Contact between shield and device housing
o Device housing not grounded
Tighten covers and close doors to make sure and
terminals do not corrode
Make sure connections have not come loose due to
vibration, including ground connections
Look for shield damage and shield continuity
Check for noise
11.1.2
Management of Change
Replacement device must be:
o HART-enabled
o Correct HART protocol version
o Tested and registered
o Supports command 48
o Comes with a DD file
o Configured for communication and diagnostics
If a HART master is added make sure there is no master class conflict
If device is added in the loop make sure the voltage is sufficient
Make sure sources of noise are not introduced
Make sure new cable is laid in the correct trays
11.1.3
HART Troubleshooting
Troubleshooting digital HART is different from
troubleshooting analog 4-20 mA
It is not possible to troubleshoot HART with a multimeter
Troubleshooting guide for HART and other field
communication:
o http://www.eddl.org/SiteCollectionDocuments/TechPap
ers/ag_Field%20Communication%20Troubleshooting.
11.1.4
HART System Management
Keep system up to date with new device types and versions
12 12
Keep System Up to Date
Without the DD files the devices cannot be configured or
diagnosed
If the IDM software is not loaded with DD for new devices
and revisions it will fall into disuse
o Only analog 4-20 mA to control system remains
Load the DD files for new device types and versions on
the control system and IDM software
Same as FF and other digital
communication
12.1.1
DD File Management
DD files are easy to download from the Internet
It is a good idea to load any DD files available
o This way the system is ready for all kinds of devices
Some systems have DD wizard that automatically
distributes the DD to all workstations
Consider using DD update services which loads DD files
onto the system automatically as they become available
12.1.1.1
DTM Driver Software Management
Ensure DTM for the device is available for the particular Windows version used
Only install the DTMs you really need
o Avoid conflicts
o Reduce burden on the computers
Ensure instrument technicians can install DTM software for new device types and versions
Instrument technicians may need to be given ‘administrator’ level password
Install DTMs on all IDM workstations
Use only certified DTMs
Use only DTMs from the original device manufacturer
o Not third-party DTMs
DTM may require license to unlock device capabilities
Make sure all DTMs are available for the new Windows version before upgrading Windows
12.1.1.2
Make Sure DD Files are Available
A replacement device must be registered and must come
with DD files
Not all HART devices have DD files
o Make sure a device comes with DD files before
purchasing it
12.1.2
Conclusion
“Get Connected”
Many plants only use HART with handheld
Engineer correctly
o Design according to the rules
o Procure tested and registered
o Install and commission according to the rules
o Integrate and setup properly
o Maintain properly
o Train people
Get a field communications expert involved