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HART operating data records
A.3 HART request and response data records
DB80: Compact message format
Byte
0
1
2
3
You can learn when the response from the field device was received by cyclically reading data
record DS81 for HART channel 0. The response is always supplied in transparent message format.
FC81: Read the response with SFB 52 to DB81
m3: CALL SFB52, DB52
The program part A M 49.1 to SPB m3 is only required if reading is to occur within a block cycle.
As long as the processing status (byte 0 of DB81) is at 3 (waiting, executing), the response has
not yet been received from the field device. As soon as the processing status changes to greater
than 3, the HART request is finished.
With a processing status of 4, the request finished without errors and the response data can be
evaluated.
With a processing status of 5, the request also finished without errors but without response data
from the field device.
With a processing status of 6 or 7, the request finished with errors. You can find more detailed
information in byte 1 of DB81 (see table "HART group fault display") and for a HART protocol error
also in byte 2 of DB81 (see table "HART protocol error during response").
102
Initial value (hex)
20
05
01
00
REQ :=M1
ID :=DW#16#200
INDEX :=81
MLEN :=200
VALID :=M49.7
BUSY :=M49.1
ERROR :=M49.6
STATUS :=MD100
LEN :=MW104
RECORD :=P#DB81.DBX0.0 BYTE 200
A M 49.1
SPB m3
BE
Comment (Hex)
Req_Control
(20 = Compact message format
60 = Compact message format with SHC string)
Number of preamble bytes (5...20, 255)
Command (CMD)
Length in bytes
Explanation
Read request
Module address
Data record number 81
Target length
Block status or error information
Target area in DB81
Equipment Manual, 09/2021, A5E50557845-AA
F-AI 8xI 2-/4-wire HART HA
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