
Safety engineering
Safety functions
Safe cam
51
EDS94AYAF EN 1.0
1.3.13
Safe cam
1.3.13.1
Description
S
afe
CA
m / SCA
When this function is executed, the current absolute position is compared to the
parameterised position limits. This binary state is displayed via status bits which can be
provided via the safe output or the safety bus. The function is activated by entering a
parameter value (> 0). The status is transmitted to the safety and standard application.
Up to four pairs of position values can be parameterised and monitored. The four position
areas can be activated and monitored in parallel.
In order to execute this function, a home position assessed from a safety−related point of
view must be available in the system which is approached before the function is executed.
1.3.14
Safe referencing
1.3.14.1
Description
S
afety
Ref
erencing / SREF
For an absolute position calculation and monitoring, the safety module requires an
absolute reference point. This function is required since the encoder systems described for
position evaluation do not provide any safe absolute position.
If absolute position−dependent functions are parameterised, the drive can only be moved
with a safely limited speed until homing is successfully completed. The SLS1−SLS4
assignment can be parameterised. When the home position is overtravelled, the
parameterised "Home Position" value is accepted as the current position value. A faulty
homing, e.g. by a missing signal edge or violation of the timing request triggers STO.
Parameterisation serves to set whether the switch−off of the voltage supply shall cause a
non−volatile storage of the current position. If the restart conditions after switching on the
voltage supply and a minimum motion (minimum homing) are complied with, a restart
can be made without a renewed homing.
Danger!
The components for detecting the home position must be mechanically
mounted in such a way that the home position cannot change, e.g. by external
influences.
An unnoticed local change of the home position causes faulty values of the
absolute position.