Siemens S7-300 - Page 78

Machine and cam data
9.7 Machine data of the axis
FM 352 electronic cam controller
78 Operating Instructions, 05/2011, A5E01071724-03
Software limit switch start and end
Address Name Type Initial value Comment
64.0
68.0
SSW_STRT
SSW_END
DINT
DINT
L# -100 000 000
L# 100 000 000
Software limit switch start
Software limit switch end
Range:
- 1 000 000 000 µm to 1 000 000 000 µm
Those axis data are only of significance to a linear axis.
The software limit switches are enabled after the FM 352 is synchronized. The range set by the
software limit switches represents the working range. The FM 352 can monitor the working range
limits.
The software limit switch start (SLS) must always be less than the software limit switch end (SLE).
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Absolute encoder (SSI)
The FM 352 is synchronized after it has received a complete frame without errors. It monitors the
software limit switches as of this time. The absolute encoder used must cover at least the working
range (from software limit switch start to software limit switch end, including the limits).
Incremental encoder and initiator
The axis is initially not synchronized after each restart of the FM 352. The assigned software limit
switches are not monitored unless the module has completed a synchronization cycle.
Relationship: working range, encoder range, traversing range
 The "working range" is defined by your task-specific software limit switch settings.
 The "encoder range" represents the effective encoder range. For linear axes, the module imposes
this range symmetrically across the working range, i.e., it shifts the encoder range in order to
equalize the distances between the software limit switches and the ends of the encoder range
(see the figure above).
 The "traversing range" represents the range of values the FM 352 is capable of processing. It is
dependent on the resolution.
The following applies: working range ≥ encoder range ≥ traversing range