Operation
7.18 Free function blocks
SINAMICS DCP
376 Operating Instructions, 09/2019, A5E34382853K
CPU time load as a result of free function blocks with the SINAMICS DCP
Processing free function blocks requires considerable computation time. If little CPU time
remains, you have to check whether all the activated function modules are required and
whether all the function blocks used need to be computed within the same sampling time.
The CPU time load can be reduced by either deactivating function modules or assigning
used function blocks to a runtime group with a longer sampling time.
Table 7- 81 CPU time load as a result of free function blocks with the SINAMICS DCP
Number of free function blocks
4 ms 6 +30%
Notes regarding the CPU time
● The actual CPU time load of the CUD can be read out in r9976. Please refer to Chapter
"CPU time load with SINAMICS DCP (Page 372)" for more information about the CPU
time load for SINAMICS DCP.
● To make your own calculations, the illustrated CPU time loads can be taken to be "linear".
This means that:
– half as many blocks in the same time slice generate half as much CPU time load, etc.
– the same number of blocks in time slices half as fast generate half as much CPU time
load, etc.
● Each individual free function block can be assigned to a runtime group via parameter
(e.g. p20032). Ten runtime groups are available. Every runtime group can be assigned a
time slice using p20000.
– The time slices that can be selected with p20000 = 1 to 1096 are calculated
asynchronously to the closed-loop control functions.
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