M. Wiens, Emerson, Shakopee, Minnesota
One day at a refinery, operators call an
instrument tech to the control room and point to the screen. “PT-639 is giving
us weird readings but everything around it seems normal. Something must be
wrong with the transmitter,” said the operator.
The tech knows this pressure instrument is in
a Division 1 part of the plant, and consequently puts in a request for a hot
work permit. Once granted, the next steps are putting on appropriate personal
protective equipment and climbing up to the mezzanine where the instrument is
mounted, verifying with the operators that the instrument is no longer controlling
a process function, unscrewing the cap and mounting the leads from a HART
communicator (FIG. 1)
to look for error codes.
This scenario happens every day in countless
facilities. It reflects a level of technology where HART-enabled instruments
must be accessed directly—usually at the transmitter itself—to retrieve data or
change configurations. There is now a much better option that does not require
upgrading I/O infrastructure at host systems or making any changes to existing wiring.
Not your everyday Bluetooth technology. Bluetooth
technology is a standard for short-range wireless communication between devices
such as mobile phones, computers, transmitters and other electronic devices. To
cover such a wide range of applications, Bluetooth technology is a family of
protocols and profiles under one banner, offering specialized controller and
host stacks so developers can optimize performance to match specific use cases.
Options have been selected within the
Bluetooth technology offering to make it suitable for industrial environments
so it can be applied to field devices mounted in process manufacturing
facilities. Using this approach, Bluetooth wireless communication is being
added to a growing variety of field devices as a method for easy configuration
and viewing of information via proprietary plant asset management softwarea.
This type of bidirectional communication empowers technicians to access data
and change configurations as needed without a wired connection.
Cybersecurity of these products is of utmost
importance, so instruments enabled with Bluetooth wireless technology have been
developed with many security features to help a company’s information
technology (IT) professionals ensure the facility stays cybersecure. Therefore,
this Bluetooth communication solution is secure out of the box with encrypted
data transfers. These security features are enabled by default and cannot be
disabled, either inadvertently or intentionally.
What can Bluetooth technology do in the
our hypothetical example, consider a common pressure instrument (FIG. 2), which may be
monitoring pressure, differential pressure (DP) flow or DP level. In most
applications, it is wired to an automation host system using a 4-20 mA with
HART loop. The primary variable is sent via the current loop. Ancillary
information (e.g., additional variables, diagnostics) is sent to a host system,
and in some cases configuration changes are sent to the instrument, via the
If the host system has HART-enabled I/O, supplementary
information may be accessible. Otherwise, HART data and configuration access must
be performed at the field device. This normally involves opening the housing
and exposing transmitter internals to potential environmental contaminants,
clipping on leads and proceeding through the list of steps at the sluggish
speed of HART. Obtaining hot-work permits complicate the procedure. Moreover,
the transmitter might not be readily accessible without a ladder, climbing out
on a catwalk or installing temporary scaffolding. It is also possible to access
the HART signal at a marshalling cabinet, but the specific terminals may be
difficult to locate.
How does Bluetooth technology, combined with
sophisticated instrument transmitter electronics, help? Several examples
A walk-through of a Bluetooth-enabled
idea of a Bluetooth-enabled plant is a bit misleading since it is not necessary
to make any modifications to the plant or its I/O. Installing Bluetooth-enabled
instruments is the only requirement, so the change can be incremental.
When an operator carries a laptop, smartphone
or tablet equipped with the appropriate app (FIG. 3), it will discover all Bluetooth enabled
instruments within a radius of approximately 15 m (50 ft). These instruments “broadcast”
their presence continuously, waiting for a technician to request a connection through
the app. Since the instrument’s radio power consumption is very low, it
operates using normal loop power.
Simply by walking around with the app, the
technician can see all the instruments within range listed on the screen. All instruments
that have established a prior secure connection display their process variable,
engineering units and operational status, much like the transmitters’ local
displays. Any that are showing a process alarm or diagnostic advisory will so
indicate. This information can be seen without having to connect to an
If an individual instrument requires
attention, the technician connects via the app, using the correct password. It
is now possible to see all variables, including those related to the process,
but also diagnostic information. If necessary, the technician can also make
configuration changes, which are written to the transmitter and logged. Calibration
actions and history are also logged in the transmitter and accessible via
Bluetooth. To protect such information, companies should apply normal password
practices for all users when deploying Bluetooth instruments.
For day-to-day instrumentation maintenance, there
is no longer any need to access an instrument directly using wires, so there is
no reason to obtain a hot-work permit, open the housing, climb up a ladder or
physically connect test leads. If the instrument is within approximately 50-ft,
horizontally or vertically, a wireless connection can be made.
If the technician needs additional
documentation to carry out a specific task, it may be possible to access it for
that specific transmitter directly from the Bluetooth app with an internet
connection via the plant’s Wi-Fi network, avoiding the need to go back to the
control room or maintenance shop. These timesavers can expedite any required
actions, allowing technicians to spend far less time in the plant environment.
The ability to communicate wirelessly over a
specific distance has additional safety benefits. For example, a technician may
be able to access an instrument in a Division 1 location from a safe distance
outside of the hazardous zone. Whatever the case, normal safety protocols for
the facility must be observed, including restrictions for any devices carried
Bluetooth communication compliments HART. The latest
Bluetooth-enabled instruments retain all the usual HART capabilities, so now
there are two options for configuration. HART still works as it always has, and
the new configuration app designed for Bluetooth technology (FIG. 4) uses the same
interface as HART communication, so trained technicians do not need to learn
new steps or menus.
However, Bluetooth communication is up to 10-times
faster than HART, which speeds up configurations and data downloads. This is
particularly useful where work must be carried out in a hazardous area and
technicians would benefit from spending less time in these locations. It also
increases productivity by reducing the amount of time required to complete each
specific task. In cases where an operation has been halted due to an instrument
issue, any time savings is very significant.
For instrumentation, Bluetooth connectivity offers
distinct advantages over traditional methods of communicating with devices in
the field. Technicians can make plant rounds and check the status of Bluetooth-enabled
devices without needing to be at grade, interfering with any operation or removing
housing covers. Any changes can be made very quickly, increasing productivity
and potentially reducing downtime.
For facilities with legacy I/O that does not
use HART, adding Bluetooth technology is a major step forward since it avoids
the need to make a physical connection to an instrument. Even if host systems
do support HART, there are often instances where it is beneficial to be in the
field near the instrument, and Bluetooth communication helps in these
situations. When in the plant, technicians can work much more quickly, easily
and safely, with the ability to check the status of any Bluetooth instrument in
seconds. This is a critical tool that should be considered for any instrument
upgrades or new installations. HP
AMS Device Configurator
Megan Wiens is a Global
Pressure Product Engineer for Emerson. She is responsible for new product
introductions and advanced diagnostic capabilities across the Rosemount
pressure portfolio. In this role, she works to implement product solutions that
improve plant safety, increase process efficiency and enhance process insight.
She earned a BS degree in chemical engineering and a BA degree in Spanish from
the University of North Dakota and is currently pursuing an MBA from the University
of St. Thomas, Minnesota.