CAN-8x23 user’s manual (Revision 3.20, Ma r/08/2012) ------
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5.2.3 PDO Communication Rule
The PDO related objects are indicated from index 0x1400 to 0x1BFF. For
the CAN-8x23, RxPDO communication objects are from index 0x1400 to index
0x140F, and RxPDO mapping objects are from index 0x1600 to index 0x160F.
The ranges of the TxPDO communication objects and the mapping objects are
from index 0x1800 to index 0x180F and from index 0x1A00 to index 0x1A0F
respectively. Moreover, each PDO communication object has its own PDO
mapping object.
For example, the first RxPDO communication object is stored in the entry
with index 0x1400, and the corresponding mapping object is stored in an entry
with index 0x1600. The object with index 0x1401 and the object with index
0x1601 are a group, and so on. The TxPDO also follows the same rules. The
first TxPDO communication object is stored in the entry with 0x1800, and the
corresponding mapping object is in the 0x1A00 entry, a nd so on. Therefore,
before users access the practical I/O channels via PDO communication, each
parameter for the PDO communications and mapping objects must be
controlled.
Besides, only PDO communications can be used in the NMT operational
state. Users can use the NMT module control protocol to change the NMT
state of the CAN-8x23. It is described in the section 5.3. Besides, during
communication via the PDO messages, the data length of the PDO message
must match with the PDO mapping object. If the data l
ength ‘L’ of the PDO
message exceeds the total bytes ‘n’ of the PDO mapping object entries, only
the first 'n' bytes of the PDO message are used by the PDO consumer. If ‘L’ is
less than 'n', the PDO message will not be disposed by the PDO consumer,
and an Emergency message with error code 8210h will be transmitted to the
PDO producer. The PDO communication set is shown as follows.