Siemens Sinumerik 840D sl Function Manual page 149

10/15
Recommendation:
The value entered for the SBR tolerance should be approx. 20% higher than the
calculated value.
A velocity overshoot must be taken into account when braking with n
overshoot must be less than the sum of $MA_SAFE_STOP_VELO_TOL and n
velocity limit or $MA_SAFE_VELO_X -- $MA_SAFE_VELO_X_HYSTERESIS
(if synchronization, hysteresis and filtering n<n
taking the appropriate measurements, as otherwise the SBR function could be
inadvertently initiated, therefore resulting in a STOP A.
Timing when the actual stop limit value is exceeded
If the safe acceleration monitoring function is active, then the following timing is
obtained when the actual stop limit value is exceeded:
Actual stop
limit value
Figure 6-12 Timing when the actual stop limit value for SBR is exceeded
Table 6-10 Explanation of the figure
Time Explanation
t The position control clock cycle, defined by the following MDs:
1
MD10050 $MN_SYSCLOCK_CYCLE_TIME
MD10060 $MN_POSCTRL_SYSCLOCK_TIME_RATIO
t Monitoring clock cycle, defined by the following MDs:
2
for 840D sl:
MD10090 $MN_SAFETY_SYSCLOCK_TIME_RATIO
for SINAMICS S120:
r9500 SI Motion monitoring clock cycle (Control Unit)
t Time between an error occurring and a limit value being reached
3
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
n
Limit value
exceeded
b)
Error case
a)
n act
t
3
t
Safety functions integrated in the system/drive
6.4 Safe acceleration monitoring (SBR)
active). This must be checked by
x
c)
Start of the
stop response
t
1
t
2
not to scale
t
6
4
t
5
t
7
=0. The
set
x
t
6-149