Safely Limited Acceleration (Sla) - Siemens SINAMICS S120 Function Manual

4.2.11

Safely Limited Acceleration (SLA)

Function "Safely-Limited Acceleration" (SLA) monitors that the motor does not violate the
defined acceleration limit (e.g. in the setup mode). SLA detects early on whether the speed
is increasing at an inadmissible rate (the drive accelerates uncontrollably) and initiates the
stop response.
SLA is effective when accelerating, however, not when braking.
Note
Safety function "Safely-Limited Acceleration" (SLA) can only be used with an encoder.
Note
Safety function "Safely-Limited Acceleration" (SLA) can only be used for 1-encoder systems.
Enabling SLA
● You enable the SLA function with p9501.20 = 1.
Selecting SLA
Select the SLA function using the PROFIsafe control word S_STW1.8 or S_STW2.8. Which
control word you use depends on the PROFIsafe telegram that you configured.
Once selected, the SLA function becomes immediately active without any delay.
You can use telegrams 30, 31, 901, 902 and 903 for SLA. These telegrams contain the
control words S_STW1.8 and S_STW2.8 and status words S_ZSW1.8 and S_ZSW2.8 for
SLA.
Acceleration limit
● You define the acceleration limit to be monitored using parameter p9578. This limit value
is applicable for both the positive and negative directions of rotation.
● When setting p9578, the following rule must be complied with:
– p9578 ≥ 10 · r9790[1]
● The possible acceleration resolution is shown by the drive in r9790:
– r9790[0] = resolution, coarse
– r9790[1] = resolution, fine
The actual accuracy of the acceleration detection depends on the type of actual value
acquisition, the gear ratios as well as the quality of the encoder being used.
● The drive indicates the velocity limit corresponding to the actual acceleration in r9714[3].
● r9789 allows the diagnosis of the finer resolution acceleration monitoring offered Index 0
indicates the actual acceleration determined. Index 1 and 2 indicate the current limit
values of the SLA monitoring.
Safety Integrated
Function Manual, 12/2018, 6SL3097-5AR00-0BP1
Description of Safety Integrated functions
4.2 Safety Integrated Extended Functions
135