11.03
3 Safety-Related Functions
3.8 Safe braking ramp (SBR) (840D from SW 4.2)
© Siemens AG 2003 All Rights Reserved
SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
3-125
n
n
x
t
STOP B/C triggered
SBR_01.DSF
Speed
tolerance
n
ist
Stopping limit value
Fig. 3-24
Characteristics of the stopping limit value for SBR
The following applies when parameterizing the SBR tolerance:
The possible speed increase after triggering STOP B/C is made up of the active
acceleration a and the duration of the acceleration phase. The duration of the
acceleration phase is one monitoring clock cycle ÜT (delay in detecting a
STOP B/C until n
set
= 0):
SBR tolerance
Actual speed for SBR = acceleration * acceleration duration
The following setting rules apply:
For a linear axis:
SBR tolerance
[
mm/min
]
= a
[
m/s
2
]
* ÜT
[
s
]
* 1000
[
mm/m
]
* 60
[
s/min
]
For a rotary axis/spindle:
SBR tolerance
[
rev./min
]
= a
[
rev./s
2
]
* ÜT
[
s
]
* 60
[
s/min
]
To determine the value, the maximum value of the acceleration values should
be taken account from the following list that is also effective for the particular
axis:
MD 32300: MAX_AX_ACCEL
MD 35200: GEAR_STEP_SPEEDCTRL_ACCEL
MD 35210: GEAR_STEP_POSCTRL_ACCEL
MD 35410: SPIND_OSCILL_ACCEL
Recommendation:
The value entered for the SBR tolerance should be approx. 20 % greater than
the calculated value.
!
Caution
During "normal" operation, speed overshoot should not unintentionally trigger
the SBR. Speed overshoot should therefore be checked by making the
appropriate measurements.
Calculating the SBR
tolerance of the actual
speed
