Free Function Blocks - Siemens SINAMICS DCM Operating Instructions Manual

10.32

Free function blocks

A logic operation, which connects several states (e.g. access control, plant status) to a
control signal (e.g. ON command), is required for controlling the drive system in a wide
variety of applications.
Along with logic operations, a number of arithmetical operations and storing elements are
becoming increasingly important in drive systems. This functionality is available as a "Free
function blocks" function module (FBLOCKS) on the drive object type of the SINAMICS
DCM.
Notes
● Exact information on the scope of the blocks, about parameter assignment and about
● This additional functionality increases the CPU time load. That means the maximum
● The free function blocks are restricted in their scope to 52 blocks per drive object (DO).
● In the SINAMICS DCM, simultaneous use of the free function blocks and the DCC
CPU time load through free function blocks with the SINAMICS DCM
Processing free function blocks requires considerable computation time. If the CPU time
becomes meager, 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- 35 CPU time load through free function blocks with the SINAMICS DCM
Time slice
16 ms
8 ms
5 ms
4 ms
2 ms
SINAMICS DCM DC Converter
Operating Instructions, 1.2012, C98130-A7066-A1-05-7619
commissioning the free function blocks is available in the "SINAMICS" Free function
blocks" manual. This chapter describes the special features of the free function blocks
with SINAMICS DCM.
possible configuration with a Control Unit may be restricted.
Furthermore, the unassigned function blocks as compared to DCC cause significantly
higher CPU time loading. If that does not suffice, the application can be implemented with
the DCC technology option. See the Drive Control Chart (DCC) chapter.
technology option are feasible.
Number of free function blocks
52
23
12
6
3
Descriptions of functions
10.32 Free function blocks
CPU time load
+30 %
+30 %
+30 %
+30 %
+30 %
499