User guide

MDX-ETHERNET User Guide 47
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Table 13.2 Actual data sizes
The following examples demonstrate setting up a network using five cyclic channels for
both IN and OUT data with the cyclic data compression first disabled and then enabled.
Table 13.3 shows the mapping parameters where five OUT and five IN cyclic data
channels are required. With data compression disabled each data channel uses 32-bits
(two data words, so a total of ten words (20 bytes) are required, Pr 15.41 = 20,
Pr 15.39 = 20).
Table 13.3 Example cyclic data channel mapping with compression disabled
It is advisable to keep 16-bit parameters paired together. This prevents mis-alignment of
cyclic data with 32-bit PLC registers when using auto-mapping facilities to configure the
Modbus TCP network. By swapping the mappings for output channel 1 with output
channel 2 and moving input channel 3 and 4 to input channel 1and 2, the data channel
structure will appear as shown in Table 13.4.
Table 13.4 Example cyclic data channel mapping with compression enabled
Parameter size (bits)
Actual data size (bits)
compression enable (Pr 15.34)
Actual data size (bits)
compression disabled (Pr 15.34)
116 32
816 32
16 16 32
32 32 32
Cyclic word Data word configuration on master Mapping
Out channel 0 2 OUT (Word 0,1) Pr 6.42, Control word
Out channel 1 2 OUT (Word 2,3) Pr 1.21, Digital speed reference 1
Out channel 2 2 OUT (Word 4,5) Pr 2.11, Ramp
Out channel 3 2 OUT (Word 6,7) Pr 4.07, Symetric Current Limit
Out channel 4 2 OUT (Word 8,9) Pr 4.10, Torque Offset Selection
In channel 0 2 IN (Word 0,1) Pr 10.40, Status word
In channel 1 2 IN (Word 2,3) Pr 2.01, Post ramp speed reference
In channel 2 2 IN (Word 4,5) Pr 4.02, Current
In channel 3 2 IN (Word 6,7) Pr 10.16, DC Bus undervoltage
In channel 4 2 IN (Word 8,9) Pr 10.17, Motor overload alarm
Cyclic word
Data word configuration on
master
Mapping
Out channel 0 1 OUT (Word 0) Pr 6.42, Control word
Out channel 1 1 OUT (Word 1) Pr 2.11, Ramp
Out channel 2 2 OUT (Word 2,3) Pr 1.21, Digital speed reference 1
Out channel 3 1 OUT (Word 4) Pr 4.07, Symmetrical Current Limit
Out channel 4 1 OUT (Word 5) Pr 4.10, Torque Offset Selection
In channel 0 1 IN ((Word 0) Pr 10.40, Status word
In channel 1 1 IN (Word 1) Pr 10.16, DC Bus undervoltage
In channel 2 2 IN (Word 2,3) Pr 4.02, Current
In channel 3 2 IN (Word 4,5) Pr 2.01, Post ramp speed reference
In channel 4 1 IN (Word 6) Pr 10.17, Motor overload alarm