Siemens SINAMICS S120 Commissioning Manual page 213

Diagnostics
Example 1
An SSI encoder without incremental tracks is used. The encoder has a singleturn resolution
of 16 bits and a multiturn resolution of 14 bits. The fine resolution p0418[x] and p0419[x] is
set to the value 2. In parameter r0482[x] (X_IST1), the product is formed from "pulses per
revolution" and fine resolution p0418[x]. If using SSI encoders without incremental tracks, the
number of pulses and singleturn resolution are identical. In our example, the actual position
value X_IST1 (r0482[x]) must therefore have changed by the following value after one
encoder revolution:
Single turn resolution * fine resolution = 2
Example 2
An SSI encoder with incremental tracks is used. In this case, incorrect SSI protocol settings
can be seen, e.g. by the fact that once the system has been switched on a different absolute
position is indicated from that before it was last deactivated.
The absolute position X_IST2 (r0483[x]) must be considered by way of a check. Following
PROFIdrive, however, just one value is displayed in this parameter if bit 13 (request absolute
value in cycles) is set to the value 1 in the encoder control word p0480[x].
This bit can be set, e.g. with the aid of the binector-connector converter.
Once switched on, the SSI encoder is now turned a few revolutions. Once switched off and
on again, the absolute position of X_IST2 (r0483[x]) must indicate an unchanged value. Only
minor deviations may occur in the fine resolution area.
Commissioning Manual
Commissioning Manual, (IH1), 01/2013, 6SL3097-4AF00-0BP3
2.14 Notes on commissioning SSI encoders
16 2
* 2 = 262144
Commissioning
211