Siemens Sinumerik 840D sl Function Manual page 327

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mination function, the plausibility of the load torque is not checked. The currently
available holding torque is displayed in r1509 "Force setpoint before force limiting".
If the automatic torque determination function is not used (MD36968
$MA_SAFE_BRAKETEST_CONTROL, bit 0 = 0), then p1532 "Torque limit offset"
should be parameterized. Also in this case, when selecting the brake test, the
holding torque required for the force due to the weight is internally measured and
the effective brake test torque adapted. Contrary to the automatic torque determi-
nation function, the plausibility of the load torque is checked.
MD36968 $MA_SAFE_BRAKETEST_CONTROL, bit 1: Criterion for reaching the
torque limit
The brake test sequence requires that during the programmed traversing distance,
the torque limit is reliably reached (MD36968 $MA_SAFE_BRAKETEST_CON-
TROL, bit 1 = 0).
If the programmed traversing distance is very short, e.g. as a result of restricted
space for the axis to move, then it can occur that the required limit value is not
reached in the short time that the axis moves (Alarm 20096 "Axis %1 Brake test
aborted, additional information %2").
Using MD36968 $MA_SAFE_BRAKETEST_CONTROL, bit 1 = 1, reaching the
programmed end position is no longer used as criterion for aborting the test. This
means that using its monitoring timer, the PLC itself can decide the wait time until
the torque limit is reached. The test can be continued if, during this time,
DB31--61.DBX62.5 is set = 1. If the torque limit is not reached, the PLC exits the
brake test with DB31--61.DBX11.0 = 0.
© Siemens AG 2015 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
Connecting Sensors/Actuators
7.6 Safe Brake Test (SBT)
7-327