Siemens SINUMERIK 840D sl Function Manual page 292

Connecting sensors and actuators
8.6 Safe Brake Test (SBT)
MD37030 $MA_FIXED_STOP_THRESHOLD: Threshold for fixed stop reached
The contour deviation that is determined is always used in the brake test to detect that the
fixed stop has been reached. The parameterization in MD37040
$MA_FIXED_STOP_BY_SENSOR is therefore irrelevant. The required threshold value must
be set in MD37030 $MA_FIXED_STOP_THRESHOLD. This means that the traversing
distance from the PLC via FC18 must be greater than this threshold value.
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 information %2" is output. The
supplementary info contains the value 2 "End position reached, motion ended".
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
demand 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 selected 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_BRAKETEST_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
FXS from the part program.
292
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated