Signal Characteristic (Without Encoder) - Siemens SINUMERIK MC Commissioning Manual

Safety functions integrated in the drive
4.11 SSM
Note
Setting of the OFF1 or OFF3 ramp-down time
If the OFF1 or OFF3 ramp-down time is too short or the difference between the SSM limit speed
and the shutdown speed is too small, the "speed below limit value" signal may not change to
1, because no actual speed value could be determined below the SSM limit before pulse
suppression occurred. In this case, the OFF1 or OFF3 ramp-down time or the margin between
SSM speed limit and shutdown speed should be increased.
4.11.1.3

Signal characteristic (without encoder)

Procedure when the "Feedback signal SSM for pulse inhibit" setting is activated
The following diagram shows the signal characteristic if property "Feedback signal SSM for
pulse inhibit" is activated. (p9509.0 = 0)
Figure 4-19 Flow chart: SSM without encoder with feedback signal SSM for pulse inhibit (p9509.0 = 0)
The speed remains below the speed limit throughout the entire monitoring period. This is the
reason that status signal "SSM (Speed below limit value)" goes to 1 (r9722.15 = 1). After the
command for pulse suppression, the motor speed drops. The internal STO is set when the
speed drops below the zero speed detection level.
In this case, the SSM status signal remains HIGH; it is frozen. The drive cannot accelerate
again, due to the internal STO selection.
150
Safety Integrated (with SINAMICS S120)
Commissioning Manual, 02/2020, A5E46305916B AB