Technical data

DPV1 SFBs According to PNO AK 1131
System Software for S7-300/400 System and Standard Functions - Volume 1/2
8-2 A5E00709327-01
Operating principle
The SFC 52 "RDREC" operates asynchronously, that is, processing covers
multiple SFC calls. Start the job by calling SFC 52 with REQ = 1.
The job status is displayed via the output parameter BUSY and bytes 2 and 3 of
output parameter STATUS. Here, the STATUS bytes 2 and 3 correspond with the
output parameter RET_VAL of the asynchronously operating SFCs (see also
Meaning of the Parameters REQ, RET_VAL and BUSY with Asynchronous SFCs).
Data record transmission is completed when the output parameter BUSY = FALSE.
Parameters Declaration Data type Memory Area Description
REQ INPUT BOOL I, Q, M, D, L, constant REQ = 1: Transfer data record
ID INPUT DWORD I, Q, M, D, L, constant Logical address of the DP
slave/PROFINET IO component
(module or submodule)
For an output module, bit 15 must be
set (e.g. for address 5:
ID:=DW#16#8005).
For a combination module, the smaller
of the two addresses should be
specified.
INDEX INPUT INT I, Q, M, D, L, constant Data record number.
MLEN INPUT INT I, Q, M, D, L, constant maximum length in bytes of the data
record information to be fetched
VALID OUTPUT BOOL I, Q, M, D, L New data record was received and valid
BUSY OUTPUT BOOL I, Q, M, D, L BUSY = 1: The read process is not yet
terminated.
ERROR OUTPUT BOOL I, Q, M, D, L ERROR = 1: A read error has occurred.
STATUS OUTPUT DWORD I, Q, M, D, L Call ID (bytes 2 and 3) or error code
LEN OUTPUT INT I, Q, M, D, L Length of the fetched data record
information
RECORD IN_OUT ANY I, Q, M, D, L Target area for the fetched data record.
Note
If you use SFB 52 to read a data record for PROFINET IO, negative values in the
INDEX, MLEN and LEN parameters are interpreted as 16-bit whole numbers with
no preceding sign.
Error Information
See Receiving an Interrupt with SFB 54 "RALRM"