Siemens SINUMERIK 840D sl Function Manual page 160

Safety functions integrated in the system/drive
7.8 Safety software cams and safety cam track (SN)
Synchronizing cam signals
As a result of system-related actual value differences, the cam signals of the monitoring
channels can have different states. In order to prevent this, the cam synchronization can be
activated. This AND's the results of both channels.
The cam SGAs at the input position of the SPL are synchronized if the user has parameterized
this using the function enable.
Cam signal synchronization is enabled using the following machine data / parameters:
for 840D sl:
MD36901 $MA_SAFE_FUNCTION_ENABLE, bit 7
for SINAMICS S120:
p9501 SI Motion enable safe functions (Control Unit), bit 7
The cam SGAs including the hysteresis, but without synchronization are displayed in the
service screen and servo trace.
Hysteresis of the two cam SGAs
When cam synchronization is activated, cam signals are output with a hysteresis that takes
into account the approach direction (see Fig. , "Hysteresis of the cam SGAs"). This helps to
prevent the SGAs from "flickering" if the axis is positioned exactly on the cam.
The magnitude of the hysteresis is determined by the following data:
for 840D sl:
MD36940 $MA_SAFE_CAM_TOL (tolerance for safety software cams)
for SINAMICS S120:
p9540 SI Motion SCA (SN) tolerance (Control Unit)
Figure 7-19
If the cam is incorrectly/inadmissibly parameterized, then this is indicated by Alarm 27033.
Configured cam hysteresis
As a result of the cam hysteresis, for increasing actual values, the cam SGAs do not switch
at the configured cam position (SN) but at the position increased by the cam tolerance
(hysteresis) (SN+TOL).
Users must carefully take this into consideration when configuring the cam positions and cam
tolerance.
160
Hysteresis of the cam SGAs
WARNING
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated