Siemens SIMATIC S7-400H System Manual page 370

S7-400 cycle and response times
19.5 Response time
DP cycle times on the PROFIBUS DP network
If you configured your PROFIBUS DP network in STEP 7, STEP 7 calculates the typical DP
cycle time to be expected. You can then view the DP cycle time of your configuration on the
PG in the bus parameters section.
The figure below provides an overview of the DP cycle time. In this example, we assume an
average value for each DP slave of 4 bytes of data.
Figure 19-7
If you are operating a PROFIBUS DP network with more than one master, you will need to
take the DP cycle time into account for each master. In other words, perform a separate
calculation for each master and add the results together.
370
DP cycle times on the PROFIBUS DP network
System Manual, 03/2012, A5E00267695-11
S7-400H