Siemens SINUMERIK 840D sl Function Manual page 1440

Detailed description
2.12 Block descriptions
2.12.9 FB 11: Brake test
Description of Functions
The braking operation check should be used for all axes, which must be prevented from
moving in an uncontrolled manner by a holding brake. This check function is primarily
intended for the socalled "vertical axes".
The machine manufacturer can use his PLC user program to close the brake at a suitable
moment in time (guide value every 8 hours, similar to the SI test stop) and allow the drive to
produce an additional torque/additional force equivalent to the weight of the axis. In errorfree
operation, the brake can produce the necessary braking torque/braking force and keep the
axis at a virtual standstill. When an error occurs, the actual position value exits the
parameterizable monitoring window. In this instance, the position controller prevents the axis
from sagging and negatively acknowledges the mechanical brake test.
The necessary parameterization of NC and Drive is described in:
References:
/FBSI/Functional Description, Safety Integrated
The brake test must always be started when the axis is at a standstill. For the entire duration
of the brake test, the enable signals of the parameterized axis must be set to enable (e.g. the
controller inhibit, feed enable signals). Furthermore, the signal to the axis/spindle DB31, ...
DBX28.7 (PLC controls axis) is to be set to 1 by the user program for the entire duration of
the test.
Before activating the signal DB31, ... DBX28.7 (PLC controls axis) the axis is to be switched
as "neutral axis" e.g. the DB31, ... DBX8.0-8.3 (Allocate NC axis to channel) is to be set to
channel 0 as well as the DB31, ... DB8.4 (activation signal when this byte is changed) is to
be set.
The return message
• about the current state can be queried in the byte DB31, ... DBB68.
• the NC about the signal DB31, ... DBX63.1 (PLC controls axis) is to be awaited before the
The axis must be able to reach the destination of this movement without risk of collision if the
brake is unable to produce the necessary torque/force.
Note
Instructions for FC 18
If FC18 is called for the same axis in the remainder of the user program, the calls must be
mutually interlocked. For example, this can be achieved via a common call of this function
with an interlocked common data interface for the FC 18 parameters. A second option is to
call the FC18 repeatedly, in which case the inactive FC18 will not be processed by the
program. A multiple-use interlock must be provided.
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block is started. The direction in which the drive must produce its torque/force is specified
by the PLC in the form of a "traversing motion" (e.g., via FC 18).
Basic logic functions: PLC basic program solution line (P3 sl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0