Siemens SINAMICS DCM Manual page 626

CPU time load through free function blocks with the SINAMICS DCM
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 10- 62 CPU time load through free function blocks with the SINAMICS DCM
Time slice
16 ms
8 ms
5 ms
4 ms
2 ms
Notes
● The actual CPU time load of the CUD can be read out on r9976. Please refer to the "CPU
time load with the SINAMICS DCM" chapter for more information about the CPU load
with the SINAMICS DCM.
● To make own calculations, the above-illustrated CPU time loads can be taken as "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
● 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.
The time slice that can be selected with p20000 = 9003 is the time slice in which the
setpoint channel (function diagrams 3105 to 3155) is calculated. One of the free function
blocks assigned to this time slice is immediately calculated before the functions of the
setpoint channel.
SINAMICS DCM DC Converter
Operating Instructions, 02.2015, A5E34763375/RS-AA/001
Number of free function blocks
52
23
12
6
3
load, etc.
ac.maher.co.ir
Descriptions of functions
10.35 Free function blocks
CPU time load
+30%
+30%
+30%
+30%
+30%
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