Siemens SIMATIC S7-200 System Manual page 462

S7-200 Programmable Controller System Manual
Sample Program for DP Communications to a CPU
A sample program in Statement List for the PROFIBUS--DP module in slot 0 for a CPU that uses
the DP port information in SM memory is shown below. The program determines the location of
the DP buffers from SMW226 and the sizes of the buffers from SMB228 and SMB229. This
information is used to copy the data in the DP output buffer to the process-image output register of
the CPU. Similarly, the data in the process-image input register of the CPU are copied into the V
memory input buffer.
In the following sample program for a DP module in position 0, the DP configuration data in the
SM memory area provides the configuration of the DP slave. The program uses the following data:
SMW220
SMB224
SMB225
SMW226
SMB228
SMB229
VD1000
VD1004
448
DP Module Error Status
DP Status
Master Address
V memory offset of outputs
Number of bytes of output data
Number of bytes of input data
Output Data Pointer
Input Data Pointer