Siemens SINUMERIK 840Di Function Manual page 1340

Detailed Description
2.12 Block descriptions
Note
The block must be called cyclically by the user program once following SPL program start-
up. The user must provide an instance DB with any number for this purpose. The call is
multi-instance-capable.
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 so-called "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
apply additional torque/additional force on top of the weight force of the axis. In error-free
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 required parameterization of NC and drive is described in:
References:
/FBSI/ Description of Functions, 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 servo disable, feedrate enable signals). The "PLC monitoring axis" (DB "Axis".DBX 28.7)
must also be set to status 1 by the user program for the entire duration of the test. Before the
"PLC monitoring axis" signal is activated, the axis must be switched to "neutral axis" status
(e.g., byte 8 must be set to channel 0 in the axis DB, activation signal must be set in the
same byte, current-status checkback can be polled in byte 68). The block must not be
started until the NC checkback via the appropriate bit (DB "Axis".DBX 63.1) has arrived. 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). 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
Note on FB 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 FC 18 repeatedly, whereby the inactive FC 18 will not be processed by the program.
A multiple-use interlock must be provided.
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PLC Basic Program Solution Line (P3 sl)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0