Siemens SINUMERIK 840D sl Function Manual page 124

Safety functions integrated in the system/drive
7.3 Safe Stops A-F
$MA_SAFE_STOP_SWITCH_TIME_D. The SBH function is automatically activated after the
timer expires.
● Effect:
The drive is braked in a group - including simultaneous axes - along the set traversing path.
For axes, the acceleration characteristic is defined so that the axes stop within the time
saved in MD36953 $MA_SAFE_STOP_SWITCH_TIME_D. Therefore, ensuring stopping
with low associated stress on the machine.
If the accelerating/braking behavior is now changed in the NC program, for a STOP D, the
axes brake with the shortest transition time of all path axes, i.e. the transition times
MD36953 must be set the same for all axes.
When running up, for all of the axes, the control checks whether the braking time set in
MD36953 is sufficient for the active acceleration characteristic of the axis. When violated,
the suppressible alarm 22001 "Channel %1 Block%2 Axis %3: Braking ramp longer than
STOP D time. Reason: %4" is output.
For spindles, the actual acceleration characteristic is not adapted. The control checks
whether the braking time, set in MD36953 $MA_SAFE_STOP_SWITCH_TIME_D, is
sufficient for all spindle operating modes and configured gear stages. When violated,
suppressible alarm 22002 "Channel %1 Spindle%2: Braking ramp longer than STOP D
time. Gearbox stage %3. Reason: %4" is output. If the spindle is in axis operation, then it
behaves just like an axis.
For an active axis or spindle coupling (with the exception of the synchronous spindle
coupling), the coupling is no longer taken into consideration, if synchronous stopping of the
coupled group is no longer safely possible within the time parameterized in MD
$MA_SAFE_STOP_SWITCH_TIME_D. For a coupled group, this is the reason that for all
axes of the coupled group, a STOP D must be set.
For the synchronous spindle coupling, when synchronous operation is reached, the
coupling is always maintained. The coupling group is always braked via the leading spindle.
If the following spindle requires a longer braking time than the leading spindle, then MD
$MA_SAFE_STOP_SWITCH_TIME_D must be appropriately increased for the leading
spindle.
When a synchronous spindle is active, STOP D should also be initiated for the leading and
following spindle.
Endlessly rotating axes are braked at the acceleration limit. The SBH function is
automatically activated after the timer expires.
When Alarm 22001/22002 is output, the following formulas are applied:
For axes with jerk limitation, the minimum braking time is increased by the additional
component:
2 * MAX_ACCEL / MAX_AX_JERK
The check is made for NECONF, RESET, unparking an axis and for programming ACC or
JERKLIM.
The MD names contained in the formulas must, corresponding to the alarm situation (the
alarm occurs when parameterizing or when programming) may have to be replaced by
other values.
124
METRIC: SAFE_STOP_SWITCH_TIME_D > MAX_AX_VELO * 1/60000 /
MAX_AX_ACCEL
INCH/ROT/SPINDLE: SAFE_STOP_SWITCH_TIME_D > MAX_AX_VELO * 1/60 / MAX_AX_AC‐
CEL
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated