Installation, Operation and Maintenance Manual
MDE 254 Rev. 1 March 2021
HART Commands 11
Section 7: HART Commands
Section 7: HART Commands
The HART Command Set provides uniform and consistent communication for all field devices.
The command set includes three classes: Universal, Common Practice, and Device Specific
(refer to Table 3). Host applications may implement any of the necessary commands for a
particular application.
• UNIVERSAL
All devices using the HART Protocol must recognize and support the universal commands.
Universal commands provide access to information useful in normal operations (e.g. read
primary variable and units).
• COMMON PRACTICE
Common Practice commands provide functions implemented by many, but not necessarily
all HART communication devices.
• DEVICE SPECIFIC
Device Specific commands represent functions that are unique to each field device. These
commands access setup and calibration information, as well as information about the
construction of the device. Information on Device Specific commands is available from
device manufacturers.
Table 3.
Universal Commands Common Practice Commands Device Specific Commands
• Read Unique Identifier
• Read Primary Variable
• Read Loop Current and
Percent of Range
• Read Dynamic Variables and
Loop Current
• Write Polling Address
• Read Loop Configuration
• Read Dynamic Variable
Classifications
• Read Device Variables
with Status
• Read Unique Identifier
Associated with Tag
• Read Message
• Read Tag, Descriptor, Date
• Read Primary Variable
Transducer Information
• Read Device Information
• Read Final Assembly Number
• Write Message
• Write Tag, Descriptor, Date
• Write Final Assembly Number
• Read Long Tag
• Read Unique Identifier
Associated with long Tag
• Write Long Tag
• Reset Configuration
Changed Flag
• Read Additional Device Status
• Perform Device Reset
• Read Device Variable Inform
• Write Number of Response
Preamble
• Read Device Communications
Statistics
• Write Burst Period
• Write Burst Trigger
• Read Burst Mode
Configuration
• Write Burst Device Variables
• Write Burst Mode
Command Number
• Burst Mode Control
• Write Device Variable Value
• Read Array
• Write Array
All slave response messages return two Command Status bytes in the first two bytes of the Data field.
The first byte is multiplexed and contains either the Communication Status (most significant bit is
set) or the Response Code (most significant bit is reset). The second byte of a slave response message
always contains Field Device Status.
The Response Data Bytes are not returned if a communications or command error is reported in the
Command Status Bytes.
To Next Page
Loading...
Need help?
General
