Communication; Notes On Communication With Hart; Hart Command - Siemens SIMATIC 6DL1 136-6AA00-0PH1 Manual

8.3

Communication

8.3.1

Notes on communication with HART

Reference is made to communication with HART in the following.
HART communication
With enabled HART operation, the analog module independently sends HART commands to the
connected field devices. This always occurs alternately on a channel-specific basis with any
pending external HART commands that arrive via the command interface of the module.
• HART command (Page 83)
• HART command interface (Page 95)
Fast mode
When processing HART commands as an SHC sequence (Successive HART Command), HART
processing is reserved for the current channel.
If a HART command with set SHC bit is recognized by the I/O module for a channel, the complete
HART command processing on the I/O module is reserved for this channel for approx. 2 seconds.
There is no processing of internal HART requests, and there is no HART command processing for
all other channels of the I/O module during this time.
SHC sequence (Page 85)
Note
• While a HART channel of the I/O module is processing an SHC sequence, and thus the
complete HART processing is reserved for this channel, the HART variables of all HART
channels are no longer updated. They remain unchanged in terms of value and quality code.
• HART commands for other channels are not processed and are acknowledged
correspondingly.
Burst mode
The I/O module does not support burst mode. HART commands with set burst bit are ignored and
are not forwarded to the connected field device.
8.3.2

HART command

Definition
HART commands are used to set the configurable properties of HART field devices (HART
parameters). HART responses are used to read out the HART parameters.
F-AI 8xI 2-/4-wire HART HA
Equipment Manual, 09/2021, A5E50557845-AA
HART function
8.3 Communication
83