Safe Speed Monitor With Encoder - Siemens SINAMICS S120 Function Manual

4.2.9.1

Safe Speed Monitor with encoder

Functional features of "Safe Speed Monitor" with encoder
The parameter p9546 "SI Motion SSM (SGA n < nx) speed limit n_x" is used to set the speed
limit. The abbreviation "SGA n < nx" indicates the safety function required for determining an
output signal when a parameterizable velocity limit has been undershot.
If the speed limit for the SSM feedback signal (n < n_x) is fallen below, the signal "Safe
Speed Monitor feedback signal active" (SGA n < n_x) is set. When the set threshold value
has been undershot, the "Safe Acceleration Monitor" (SAM) function is also deactivated (see
p9568). If p9568 = 0, then p9546 (SSM feedback signal) is also used as a minimum
threshold for the SAM monitoring.
A hysteresis can be configured for the SSM function via p9547. In this way, a more stable
signal characteristic of SSM can be achieved at speeds close to the monitoring threshold
(p9546).
When hysteresis is configured, then the velocity (or speed) determined by the two channels
may not differ by more than the difference between p9546 and p9547. Otherwise it would be
theoretically possible that one channel returns a HIGH signal and the other a LOW signal for
SSM.
The following diagram shows the characteristic of the safe output signal SSM when the
hysteresis is active:
Figure 4-15 Safe output signal for SSM with hysteresis
The output signal for SSM is smoothed by setting a filter time with a PT1 filter (p9545).
Safety Integrated
Function Manual, 12/2018, 6SL3097-5AR00-0BP1
Description of Safety Integrated functions
4.2 Safety Integrated Extended Functions
123