Siemens Sinumerik 840D sl Function Manual page 326

Connecting Sensors/Actuators
7.6 Safe Brake Test (SBT)
If the travel distance that is entered is too short, after the end position is reached
on the setpoint side, Alarm 20096 "Axis %1 brake test aborted, additional informa-
tion %2" is output. The supplementary info contains the value 2 "End position
reached, motion stopped".
MD36966 $MA_SAFE_BRAKETEST_TORQUE: Holding torque, brake test
The machine manufacturer must parameterize the required brake test torque as
percentage in the axis--specific MD36966 $MA_SAFE_BRAKETEST_TORQUE.
The magnitude of the torque to be configured is orientated to the maximum holding
force of the brake, according to the data sheet, that should be checked. Internally,
this is used to calculate the drive torque that is required in addition to the weight of
the axis to load the brake. The drive torque to load the holding brake is limited to
the maximum motor torque if the desired test torque would require a higher drive
torque.
Value for MD36966 = (test torque of the brake / p2003) * 100
The value from $MA_SAFE_BRAKETEST_TORQUE refers to the reference
torque or the reference force from drive parameter p2003, whose image is saved in
$MA_SAFE_BRAKETEST_TORQUE_NORM.
The magnitude of the torque to be configured is orientated to the maximum holding
force of the brake to be tested.
Incorrect parameterization in MD $MA_SAFE_BRAKETEST_TORQUE could
mean that the drive with reduced torque cannot even apply the required holding
torque. These parameter assignments are detected when the brake test is se-
lected and results in Alarm 20095 "Axis %1 inadmissible holding torque %2".
MD36967 $MA_SAFE_BRAKETEST_POS_TOL: Position tolerance, brake test
The monitoring window for the maximum permissible movement during the brake
test is defined in the axis--specific MD36967 $MA_SAFE_BRAKE-
TEST_POS_TOL. The PLC actively monitors this position window -- from the start
of the brake test and not only when it has been detected that the fixed stop has
been reached. This is a difference when compared to activating the traversing to
the fixed stop function from the part program.
MD36968 $MA_SAFE_BRAKETEST_CONTROL, bit 0: Sequence check for the
brake test
Principally, the automatic determination of the load torque available using
MD36968 $MA_SAFE_BRAKETEST_CONTROL, bit 0 = 1 is preferred. This is
because over the complete traversing path of a suspended axis the torque situa-
tion continually changes to some extent or the other. The torque situation is, e.g.
dependent on the different tools/workpieces being used and can vary significantly.
Using the automatic torque determination function, the instantaneous holding
torque available at standstill is automatically determined (mAct from Fig. 7-35) and
is temporarily used as average value for the torque limiting in the drive. In this
case, it must be ensured that at the start of the test, the brake is open, otherwise
an incorrect reference value will be determined. With the automatic torque deter-
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
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