Siemens SIMATIC NET CP 1542-5 Equipment Manual page 30

Configuration, program blocks
4.3 Program blocks for communication and distributed I/O
System blocks and
system functions
DP_TOPOL
WRREC
RDREC
GETIO
SETIO
GETIO_PART
SETIO_PART
D_ACT_DP
DPRD_DAT
DPWR_DAT
RALRM
Refer to the documentation of the program blocks in the information system of STEP 7.
Calling program blocks (instructions) for distributed I/O
Several calls are necessary for the instructions of the distributed I/O.
The time required to process the job depends on load, round-trip time and transmission
speed. If these instructions are called in a loop within one cycle, the cycle time could be
exceeded.
Exception: Only one call is required for RALRM "receive alarm".
Program blocks for DPV1 according to the PNO standard (PROFIBUS user organization):
• RDREC
"Read data record from a DP slave" corresponds to SFC59 in terms of function
• WRREC
"Write data record to a DP slave" corresponds to SFC58 in terms of function
• RALRM
"Read interrupt information from a DP slave" - call in an interrupt OB
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Meaning when used with CM
Detecting the topology for the DP master system
Writing the data record of a DP slave
Reading the data record of a DP slave
Reading the process image of a DP standard slave
Transferring the process image of a DP standard slave
Reading the process image partition of a DP standard slave
Transferring the process image partition of a DP standard slave
Disable / enable DP slaves
Reading consistent data of a DP standard slave (user data)
Writing consistent data of a DP standard slave
Event-driven reading of interrupt information (diagnostics, pull/plug,
hardware interrupt) and DPV1-specific interrupts (update, status, vendor-
specific interrupt)
Equipment Manual, 01/2023, C79000-G8976-C326-05
SIMATIC CP 1542-5