Siemens SINUMERIK 840D Description Of Functions page 450

8 Application examples
8.3 Testing the function of the brake mechanical system
8.3 Testing the function of the brake mechanical system
8.3.1 Applications
The brake mechanical system test should be used for all axes which must be
prevented from moving in an uncontrolled manner by a holding brake. This test
function is primarily intended for so-called vertical axes. The brake test fulfills
the requirements of control Category 2 according to EN 954-1.
The functionality is based on "traversing to a fixed endstop" (FXS). The
traversing to fixed endstop can be individually parameterized to test the
function of the brake mechanical system. It is activated and de-selected from
the PLC. For further details on traversing to fixed endstop, refer to /FB1/, F1.
The machine manufacturer can use his PLC user program to close the brake at
a suitable moment in time (nominal value, every 8h similar to the SI test stop)
and initiates the drive to produce an additional torque/additional force
equivalent to the weight of the axis. In a fault-free state, the brake can apply the
necessary force, i.e. the axis will hardly move.
When there is a fault condition, the actual position value leaves the
parameterizable monitoring window. In this case, traversing to fixed endstop is
terminated so that the position controller can prevent the axis falling. The brake
test is then negatively acknowledged.
The brake test must always be started when the axis is at standstill (also refer
to Chapter 8.3.5 "Activation"). The direction in which the drive produces force is
specified by the PLC using a "traversing motion" via FC 18. The destination of
this traversing motion must be able to be reached without incurring any
potential hazard in the case that the brake cannot provide the necessary force.
8.3.2 Parameterization
The following axial NCK machine data are available to the user for
parameterizing the function test of the brake mechanical system:
$MA_FIXED_STOP_ The function test of the mechanical brake system is enabled by setting bit 1 in
MODE $MA_FIXED_STOP_MODE. If the user needs to travel to a fixed stop with this
axis from the part program, bit 0 can also be set. An internal monitoring is
performed 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 stop still
active" is issued.
$MA_SAFE_ The machinery manufacturer must parameterize the total required brake
BRAKETEST_TORQUE holding torque in the axial MD $MA_SAFE_BRAKETEST_TORQUE. Internally,
this is used to calculate the drive torque needed in addition to the weight of the
axis as braking load.
8-450
SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
- $MA_FIXED_STOP_MODE
- $MA_FIXED_STOP_THRESHOLD
- $MA_SAFE_BRAKETEST_TORQUE
- $MA_SAFE_BRAKETEST_POS_TOL
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11.03