Siemens SINUMERIK 840D sl Function Manual page 224

Connecting Sensors/Actuators
7.4 Safe brake test (SBT)
$MA_FIXED_STOP_MODE
The function test of the mechanical braking system is enabled by setting bit 1 in
$MA_FIXED_STOP_MODE. If the user needs to travel to a fixed endstop with this
axis from the part program, bit 0 can also be set. It is internally monitored to check
that only one type of traverse to fixed endstop is active at a time. In the case of an
error, Alarm 20092, "Axis % 1 Travel to fixed endstop still active" is issued.
$MA_SAFE_BRAKETEST_TORQUE
The machinery construction OEM must parameterize the total required brake hold-
ing torque in the axial MD $MA_SAFE_BRAKETEST_TORQUE. Internally, this is
used to calculate the drive torque that is required in addition to the weight of the
axis to load the brake.
For SINAMICS S120 the drive torque is determined when the function test is se-
lected. It is thus possible to take into account any deviation from the torque due to
weight parameterized in drive parameter p1532 (or force due to weight). This en-
sures that the brake test can also be carried-out with varying machine loads (e.g.
different workpieces or tools). The drive torque to load the holding brake is limited
to the maximum motor torque if the desired braking torque would require a higher
drive torque.
If the load torque at an axis changes so significantly that a sensible value cannot
be parameterized in drive parameter p1532, then the automatic determination of
the load torque available must be activated using $MA_SAFE_BRAKET-
EST_CONTROL.
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 03.2006 Edition
© Siemens AG, 2006. All rights reserved
03.06