Siemens Sinamics S110 Function Manual page 302

Drive functions
7.3 Function modules
Calculation time load for firmware version 4.3 and higher
For firmware version 4.3 and higher, after a download or a parameter change (e.g. where the
sampling time of a runtime group is changed) using the configuration data, the Control Unit
(CU) determines the calculation time load to be expected (including the load associated with
FBLOCKS). This value is displayed in r9976 (system utilization) for the system as a whole.
If the calculated average calculation time load for the system as a whole r9976[1] or the
maximum utilization (including the interruption as a result of time slices with a shorter
sampling time) in a sampling time r9976[5] exceeds 100.00%, this generates fault F01054
(CU: System limit exceeded) to be output with fault reaction OFF2.
The utilization is calculated on the Control Unit, i.e. the utilization values are displayed in
STARTER/SCOUT in online mode only.
The resulting calculation time load caused by FBLOCKS depends on the following:
● Number of calculated runtime groups
● Sampling time of the runtime groups
● Number of calculated blocks
● Calculated block types
The proportion of the calculation time load associated with FBLOCKS is displayed in
r20005[0...9] for runtime groups 0 to 9 (as of firmware version 4.3). Note that the calculation
time load for a runtime group k can only be calculated if this has been logged on for cyclic
processing (p20000[k-1] ≠ 0).
For firmware version 4.3 and higher, and unlike with version 4.1, if a parameter is changed
(in the STARTER online mode) that has an influence on the calculation time load (e.g.
changes the sampling time of a runtime group in FBLOCKS), the drive unit immediately
recalculates r9976 (and r20005). For parameters which can only be changed in the device
states C1 (commissioning device) or C2 (commissioning drive object), i.e. only when
STARTER/SCOUT is in the offline mode, r9976 is only updated after the project has been
downloaded and the Control Unit has powered up.
For firmware version 4.3, the calculation time load displayed in r9976 can be up to 100.00%
without triggering a fault.
Number of possible hardware sampling times
The sampling times for the runtime groups can be selected in p20000[x] as a multiple of
r20002 (basic sampling time of hardware time slices), a multiple of r20003 (basic sampling
time of software time slices), or on the basis of the sampling time of a basic SINAMICS
system function (e.g. when p20000[x] = 9003 == "before setpoint channel" from the sampling
time of the setpoint channel).
Only sampling times to which the following applies can be set as hardware sampling times:
1 ms ≤ T_sampling ≤ r20003 - r20002 in p20000[x]
Sampling time r20003 is always a software sampling time regardless of whether it is set as
p20000[x] = 1001 (== 1 x r20003) or as a multiple of r20002 (p20000[x] ≤ 256).
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Function Manual, 01/2011, 6SL3097-4AB10-0BP3
Function Manual