Safe Stop 2 (Ss2) - Siemens SINAMICS S120 Function Manual

4.2.7

Safe Stop 2 (SS2)

Note
The "Safe Stop 2" (SS2) safety function can only be used with an encoder.
The safety function "Safe Stop 2" (SS2) is used to brake the motor of the OFF3 deceleration
ramp (p1135) safely with transition after the delay time (p9552) has expired in to the SOS
state (see Chapter "Safe Operating Stop (SOS) (Page 103)"). The delay time set must allow
the drive to brake to a standstill from every speed of the operating process within this time.
The standstill tolerance (p9530) may not be violated after this time.
After braking, the drives remain in speed control mode with the speed setpoint n = 0. The full
torque is available.
The default setpoint (e.g. from the setpoint channel, or from a higher-level controller)
remains inhibited as long as SS2 is selected.
During braking, one of the following functions is active:
● If p9506 = 0:
Braking is monitored with the "Safe Acceleration Monitor" function (see Chapter "Safe
Acceleration Monitor (SAM) (Page 150)").
● If p9506 = 2:
Here, also for SS1, the monitoring function "Safe Brake Ramp" is active (see Chapter
"Safe Brake Ramp (SBR) (Page 152)").
The selection and monitoring of the acceleration (SAM) are realized through two channels –
however, braking along the OFF3 ramp, only through one channel.
● Effect on "Speed setpoint limit active" (r9733[0...2]):
If SS2 (≙ STOP C), setpoint 0 is specified in r9733[0...2].
Interruption of the ramp function with OFF2
Activating SS2 can mean that the higher-level controller (PLC, motion controller) which
specifies the speed setpoint, interrupts the ramp function (e.g. with OFF2). The device
behaves in this way as a result of a fault reaction triggered by OFF3 activation. This fault
reaction must be avoided by assigning appropriate parameters or configurations.
Safety Integrated
Function Manual, 12/2018, 6SL3097-5AR00-0BP1
Description of Safety Integrated functions
4.2 Safety Integrated Extended Functions
105