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

Time Explanation
t Time until the configured stop response becomes effective
4
typical 1.5 monitoring clock cycles, maximum 2 monitoring clock cycles + 1 position controller clock cycle)
(
t Time until the stop response that was initiated actually starts
5
typical 2 position controller clock cycles, maximum 2 position controller clock cycles
STOP C:
STOP D/E: typical 2 interpolation clock cycles, maximum 2 interpolation clock cycles + 2 monitoring clock cycles
t Time required to bring the axis to a standstill.
6
This time and thus the residual distance traveled by the axis is determined by the axis design (motor, mass, fric‐
tion, ...) and the configured stop response (STOP C is faster than STOP D).
Note:
Each axis must be measured during commissioning (start-up) to determine the distance that it travels between the limit switch
being violated and it coming to a standstill.
7.8

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 specific axes, thereby
replacing a hardware solution.
Safe referencing
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 to be safe if the axis was 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 the 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.
Functional features
The most important functional features include:
● Cam positions are safely defined and evaluated as a software function
● Working ranges/zones are defined
Safety Integrated
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
WARNING
Safety functions integrated in the system/drive
7.8 Safety software cams and safety cam track (SN)
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