Siemens SIMATIC ET 200SP HA - Hart; HART Protocol

7.1.2 HART
De󹪝nition
"HART" stands for "Highway Addressable Remote Transducer" = via communications addressable
remote 󹪝eld devices (sensor or measuring transducer or 󹪝nal controlling element).
The HART functionality also enables you to use the I/O module to exchange data with the
connected 󹪝eld devices. The HART protocol is generally accepted as a standard protocol for
communication with intelligent 󹪝eld devices: HART is a registered trademark of the HART
Communication Foundation (HCF), which owns all the rights to the HART protocol. You can 󹪝nd
detailed information about HART in the HART speci󹪝cation.
7.1.3 HART protocol
De󹪝nition
The HART protocol describes the physical form of the transfer: transfer procedures, message
structure, data formats and commands.
Description
Each HART message frame sent from the analog module to the connected 󹪝eld device (request
frame) and each HART message frame received from the 󹪝eld device (response frame) has the
following basic structure.
PREAMBLE STRT ADDR COM BCNT STATUS DATA CHK
PREAMBLE: Bytes (0xFF) for synchronizing.
5 bytes
STRT: Start character (start delimiter)
ADDR: Address of the 󹪝eld device (1-byte; short address or 5-byte; long address)
COM: HART command number
BCNT: Byte count, number of bytes to follow without checksum
STATUS: HART device status (1st and 2nd status byte). Only present for a response frame.
HART device status (Page 41)
DATA: Transferred user data / parameters, quantity depending on command (0…230
bytes)
CHK: Checksum
With the exception of the preamble bytes, this structure is contained in the communication data
of the HART command interface.
HART job and response data records (Page 74)
HART function
7.1 Use
AI 4xI 2-/4-wire HART ISOL HA
38 Equipment Manual, 07/2022, A5E50101523-AB