Figure 10: Si Configuration - Siemens Simatic Manual

Fail-safe function blocks for storage and retrieval machines
POS_SI_T_SAMPLE
p9505
Rotary axis

Figure 10: SI configuration

As described above, the drive type must be set to rotary axis. The modulo range must be selected so
that during one cycle in the PLC, two rollovers cannot occur. As a consequence, this value depends
on the maximum velocity.
See section
"Mechanical configurati-
on"
Figure 11: Encoder parameterization
The modulo value at POS_SI is directly converted into the SLU unit in the block;
POS_SI_RESOLUTION and SLU_DEFINITION define the conversion factor.
Configuring the mechanical system:
Converting from degrees to a unit length must be realized using the gearbox ratio. This is realized by
entering divisor 360 for the number of encoder revolutions. Based on the number of load revolutions,
the feed constant/spindle pitch can now be specified, which corresponds to SLU_DEFINITION – i.e.
the relationship between mm/SLU at F_SAFE_POS.
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S7-Distributed Safety/SIMATIC Safety - fail-safe function blocks for storage and retrieval machines