Ss2 With External Stop (Ss2E) - Siemens SINAMICS S120 Function Manual

4.2.7.1

SS2 with external stop (SS2E)

Unexpected axis motion
When function "Safe Stop 2 with external stop" (SS2E) is active, during the delay time
(p9553) the speed follows the setpoint issued from the higher-level control system. As a
consequence, unexpected axis motion is possible, which can lead to severe injury and
death.
• Prevent persons from entering the danger zone of the machine or plant during the delay
Figure 4-7
With external stop, "Safe Stop 2" functions in principle exactly the same way as described in
the previous sections. Note, however, the following differences:
Differences between "Safe Stop 2 with OFF3" and "SS2 with external stop (SS2E)"
● If SS2 with external stop is selected, the drive does not brake the motor autonomously
but follows the defined speed setpoint.
● During delay time p9553, the brake ramp (SBR) and the acceleration (SAM) are not
monitored and there is no standstill detection.
● SOS becomes active after the delay time p9553 expires.
When function SS2E is active, the higher-level control must issue the speed setpoint so
that at the latest after delay time p9553 expires, the motor has come to a complete
standstill.
● In order to activate "Safe Stop 2 with external stop", set p9501.18 = 1.
● The PROFIsafe control word S_STW2.28 selects the SS2E function. PROFIsafe
S_STW2.28 is contained in telegrams 31, 901, 902, and 903.
Safety Integrated
Function Manual, 12/2018, 6SL3097-5AR00-0BP1
WARNING
time (p9553), for example, by keeping protective devices interlocked.
Selecting function SS2E
Description of Safety Integrated functions
4.2 Safety Integrated Extended Functions
107