Lenze DDS System bus CAN for PLC - Manual (Page 43)

System bus (CAN) for Lenze PLC devices
"CAN" system bus interface configuration
3−9
l
PLC−Systembus EN 2.0
3.10.1 Functional principle considering as example
Task
Within the PLC, a function has been realised from the user side, which can be parameterised via the
user code C3200/5. The index 21375
dec
is automatically assigned to code C3200:
Index = 24575
dec
− code = 24575
dec
− 3200 = 21375
dec
On the basis of the communication profile used, this function, however, is to be parameterisable via
the index 4101
dec
/subindex 2 instead.
Solution
Via the functions of the LenzeCanDSxDrv.lib function library, index 4101
dec
/subindex 2 is simply
diverted to code C3200/5 within the PLC, so that the communication profile can be used unchanged.
Functional principle
The operating system (as of V6.0) of the Lenze PLCs contains a so−called "mapping table". With this
table up to 256 indexes within the PLC can be "mapped" to other codes than to those which are
automatically allocated.
If a CAN telegram arrives and the index is in the valid range, it is checked whether this index is listed
in the mapping table.
·
If the index is listed in the mapping table, the code which has been newly assigned to this
index in the mapping table is accessed.

·
If the index is not listed in the mapping table, the code which is automatically allocated is
accessed, resulting from the above−mentioned formula.
‚
SDO telegram
Index number
valid ?
CAN subindex
4101
yes
Index access: 4101/2
Code access: C3200/5
Mapping table
CAN index Lenze code Lenze subcode
2 3200 5
4101 1
20000 0
3200 4
3000 0
SDO telegram
Index number
valid ?
CAN subindex
4101
yes
Index access: 21475/1
Lenze code = 24575 - Index = 24575 - 21475 = 3100
Code access = C3100/1
Mapping table
CAN index Lenze code Lenze subcode
2 3200 5
4101 1
20000 0
3200 4
3000 0
 ‚
Fig. 3−2 Process of diverting indexes to codes