Siemens SIMATIC ET 200SP Manual page 38

HART function
6.1 How HART works
Table 6-2
Command
36
37
41
43
Structure of the HART protocol
Each HART frame sent from the AI-DI 16/DQ16x24VDC HART HA to the connected field
device (job frame) and each HART frame (response frame) received by the field device has
the following basic structure:
PREAMBLE
PREAMBLE:
STRT:
ADDR:
COM:
BCNT:
STATUS:
DATA:
CHK:
With the exception of the preamble bytes, this structure is contained in the communication
data of the HART command interface. See section HART job and response data records
(Page 81).
HART responses always contain data. Together with a HART response, status information
(HART device status, 1st and 2nd status bytes) is always sent together with a HART response.
You should evaluate these to make sure the response is correct.
38
Examples of common practice commands
Function
Sets high range limit
Sets low range limit
Perform self-test
Sets the primary variable to zero
STRT ADDR COM
Bytes (0xFF) for synchronization.
5 to 20 bytes depending on parameter assignment
Start character (start delimiter)
Address of the field device (1-byte short address or 5-byte long address)
HART command number
Byte count, number of consecutive bytes without checksum
HART device status (1st and 2nd status byte). Only present for a response
frame. For structure of HART device status, see below.
Transferred user data / parameters, quantity depending on command (0...230
bytes)
Checksum
Input/output module AI-DI 16/DQ16x24VDC HART HA (6DL1133-6EW00-0PH1)
BCNT STATUS
Manual, 05/2017, A5E39294170-AA
DATA CHK