Siemens SINAMICS S120 Function Manual page 171

Gearbox switchover without increased position tolerance
In order to switch over the gearbox stage, where no increased tolerance is required for the
crosswise comparison of the actual positions, proceed as follows:
1. Set the new gearbox stage using bits 0 to 2 in byte 3 of S_STW2.
2. The actual values are then synchronized once automatically. This synchronization is used
to compensate any possible difference that occurs between the position actual values of
the two monitoring channels as a result of the switchover operation.
The new gearbox stage is then active.
Figure 4-26 Gearbox switchover from stage "0" to "1" without increased position tolerance
Safety Integrated
Function Manual, 12/2018, 6SL3097-5AR00-0BP1
Description of Safety Integrated functions
4.2 Safety Integrated Extended Functions
169