| HART 7 is a major
enhancement to the HART® Protocol with many new features that
enhance communication with HART-enabled devices. Perhaps the most
significant of these new features is the new capability for wireless
communication enabled by WirelessHARTTM.
The WirelessHART technology described in the HART 7.0 Specifications
defines an interoperable standard for wireless communication in
process measurement and control applications. This new capability
combines the Power of HART with established and proven industry
standards and technologies for wireless communication.
WirelessHART opens the door to new applications and opportunities
for economic gain for both HCF members and industry users. This
new technology leverages the capability of HART-enabled field device
and host system products to be full participants in the wireless
network and expands the reach of HART Communication into plant areas
and applications that were not possible before.
The user experience and the guiding principle of backward compatibility
is preserved. WirelessHART-enabled devices use the same HART command
structure and work with the same software applications and tools
as their 4-20mA based counterparts.
Following is a summary of key enhancements in the HART 7.0 Specifications.
Wireless
A major new enhancement to the HART technology providing additional
capabilities to monitor the performance of plant assets in areas
that were uneconomical or technically difficult with wired systems.
This new enabling technology provides reliable, robust and secure
wireless communication using standard IEEE 802.15.4 radios at 2.4
GHz for global application with Channel Hopping, Mesh Networking
and robust Security appropriate for process applications. Five new
specifications and improvements to several existing specifications
describe the WirelessHART technology and the requirements for devices,
adapters, gateways and network managers. The WirelessHART User Guide
provides a good overview of the technology and should be read first
before the specifications. The User Guide is not a specification
and consequently, does not appear on the ballot.
New Wireless Documents
- WirelessHART User Guide – HCF_LIT-086
- Wireless Physical Layer Specification – HCF_SPEC-065
- TDMA Data-Link Layer Specification – HCF_SPEC-075
- Network Management Specification – HCF_SPEC-085
- Wireless Command Specification – HCF_SPEC-155
- Wireless Devices Specification – HCF_SPEC-290
Expanded Manufacturer Codes
Widespread growth and adoption of the HART Protocol has resulted
in the available code space for 8-bit Manufacturer ID Codes being
exhausted. Resolution requires the expansion of Manufacturer ID
Codes from 8-bits to 16-bits. Previous addendums to the Data Link
Layer Specification, Command Summary Specification and Universal
Command Specification that are proven and already in use have been
incorporated into this revision of the HART Protocol Specifications.
Time Stamped Data
New Data Type (Time) for Time Stamping of Device Variable Values
in Universal Command 9 response. This new capability enables the
Time Stamping of process variable values at the Field Device and
their reporting to host applications via Command 9 with the Time
Stamp or time interval from the previous value. Also, Common Practice
Commands to set the device time of day have been added.
Enhanced Burst Mode
Burst mode communication has been enhanced to allow the bursting
of more than one HART message and the ability to specify time interval
or frequency for how often the message is to be sent (burst frequency).
A form of event reporting is also defined enabling devices to automatically
send message noting a change in Command 48 status or a change to
the Configuration Change Counter.
Upgrade of Command 38 & 48 to Mandatory
These Common Practice Commands for Device Specific Status and reset
of the Configuration Change Flag are upgraded to “Universal”
status with HART 7.
Enhanced Sub Device & I/O System
Commands
New Common Practice Commands have been defined to support the set-up
and operation of Wireless Adapters and I/O Systems.
Read Trend Command
New Common Practice Command to read multiple values (or the trend)
for a specified Device Variable.
Aggregated Read Command
New Common Practice Command to support expedited upload of Device
Configuration enabling more than one command response to be read
at a time.
Common Tables Additions
New Common Tables Additions to support Wireless and all other enhanced
functionality.
Discrete Applications
This new Specification establishes the framework for defining the
application of HART Communication to devices for point detection
or discrete on/off type functionality.
ORDER HART 7 SPECIFICATIONS
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