Safety Software Cams And Safety Cam Track (Sn); Safety Software Cams And Safety Cam Track - Siemens Sinumerik 840D sl Function Manual

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6.8

Safety software cams and safety cam track (SN)

Description
The "safe software cams" function (SN) can be used to implement safe electronic
cams, safe range detection or working zone/protection zone delimination for spe-
cific axes, thereby replacing the hardware solution.
Warning
!
The enabled cam signals are immediately output when the control system is
powered--up, this output is however only safe after safe referencing (this is
signaled using the SGA "Axis safely referenced").
The cams are only considered as being safe if they were safely referenced. This is
the reason that the user must interlock this SGA with the cam SGA.
During the time in which the measuring system of the machine axis is switched off,
it is not permissible that the axis is mechanically moved. Otherwise this results in
an offset between the last buffered actual position and the real actual position of
the machine axis. This would lead to an incorrect synchronization of the measuring
system resulting in danger to personnel and machine.
If axis motion cannot be prevented mechanically in the shutdown state, either an
absolute encoder must be used or the axis must be referenced again with
reference point approach after switching on.
Features
The most important features include:
S Cam positions are safely defined and evaluated as a software function
S Working ranges/zones are defined
Tolerance for SN
Owing to variations in the clock cycle and signal run times (signal propagation
times), the cam signals of the two monitoring channels do not switch simulta-
neously and not precisely at the same position. A tolerance bandwidth can there-
fore be specified for all cams using the following machine data/parameters. Within
this bandwidth, the signal states for the same cam may be different in the two
monitoring channels.
for 840D sl:
MD36940 $MA_SAFE_CAM_TOL
for SINAMICS S120:
p9540 SI Motion SCA (SN) tolerance (Control Unit)
© Siemens AG 2015 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
Safety functions integrated in the system/drive
6.8 Safety software cams and safety cam track (SN)
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