Mapping Limitations; Disabling Mappings - Leroy-Somer digitax st User Manual

7.5

Mapping limitations

When setting mapping values care should be taken not to exceed the data size set in
Pr MM.05 (or Pr MM.39 and Pr MM.40). The data size depends on the size of the
mapped parameter and if data compression is turned on or not (see Table 7.7).
Table 7.7 Actual data sizes
Parameter size (bits)
16
32
Consider the following example:
• mapping Pr MM.10 to a 32-bit value and MM.11 to a 16-bit value
• mapping Pr MM.20 to a 32-bit value and MM.21 to a 32-bit value
• data compression turned on (Pr MM.34 set to ON)
would require the following settings:
• Pr MM.39 = 3
• Pr MM.40 = 4
If the size of the input and output mappings are identical then Pr MM.05 can be used to
set the mapping length.
7.6

Disabling mappings

Any unused mapping parameters (Pr MM.10 to Pr MM.19 and Pr MM.20 to Pr MM.29)
should be set to 0.
Having unmapped channels between valid mapped channels is not permitted and will
NOTE
result in a configuration error (i.e. Pr MM.06 will indicate -3).
28
Actual data size (bits)
compression on
1
8
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Actual data size (bits)
compression off
16
16
16
32
SM-PROFIBUS DP-V1 User Guide
32
32
32
32
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