Siemens SIMATIC ET 200SP Manual page 67

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: Reading of the response to DB81 with SFC 59
m3: CALL SFC 59
The program part A M 49.1 to SPB m3 is only required if reading is to occur synchronously.
As long as "0x03" is in byte 0 of DB81, the response has not been received from the field device.
Positive response data that you can evaluate is available from the field device as soon as bit 2
= 1 in byte 0.
If there are errors in the response data, see the "HART group fault display" tables in byte 1 or
"HART protocol error during response" in byte 2 of the field device response.
Analog Output Module AQ 4xI HART HF
Manual, 05/2019, A5E35098013-AA
REQ :=1
IOID :=B#16#54
LADDR :=W#16#200
RECNUM :=B#16#51
RECORD :=P#DB81.DBX0.0 BYTE 75
RET _ VAL :=MW100
BUSY :=M49.1
A M 49.1
m3
BE
A.2 HART operating data records
Appendix
65