Siemens SINUMERIK 840D sl Function Manual page 146

Safety Functions Integrated in the System/Drive
6.4 Safe acceleration monitoring (SBR)
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
limit value
Fig. 6-11
Table 6-10 Explanation of the diagram
Time Explanation
t The position control clock cycle, defined by the following MDs:
1
MD 10050: $MN_SYSCLOCK_CYCLE_TIME
MD 10060: $MN_POSCTRL_SYSCLOCK_TIME_RATIO
t Monitoring clock cycle, defined by the following MDs:
2
for 840D sl:
MD 10090: $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
t Time until a limit value violation is detected
4
(typical 1 monitoring clock cycle, maximum 1.5 monitoring clock cycles + 1 position controller
clock cycle)
t Response time that is required to introduce the stop response
5
(typical 2 monitoring clock cycles, maximum 2.5 monitoring clock cycles + 1 position controller
clock cycle)
t Time until the stop response that was initiated starts
6
(typical 2 ms, maximum 3 position controller clock cycles + 8 ms)
t Time required to bring the axis to a standstill.
7
This time and thus the residual distance traveled by the axis is determined by the axis design
(motor, mass, friction, ...).
6-146
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition
n
Limit value
exceeded
stop
b)
Fault
a)
n act
t
3
Timing when the actual stop limit value for SBR is exceeded
c)
Start of the
stop response
t
1
t
2
not to scale
t
t
6
4
t
5
t
7
© Siemens AG 2008 All Rights Reserved
05.08
t