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CHAPTER5 CANOPEN COMMUNICATION FUNCTION
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5.1.2 PDO(Process Data Object)
The real-time data transfer is using the PDOs.
There are two kinds of PDO transmission modes. One is a synchronization (SYNC), the other is
asynchronization message (Remotely Request, Event Driven, Timer Driven).
These PDO services use the push / pull models. The PDOs have Transmit-PDOs (maximum data size is 8
bytes) and Receive-PDOs (maximum data size is 8 bytes). These data type and these mapping are
defined by the Object Dictionary.
The following table is the PDO parameter indexes, the data types and the objects.
Index Type Object Notes
1400h 20h 1
st
receive PDO communication parameter
1401h 20h 2
nd
receive PDO communication parameter
1402h 20h 3
rd
receive PDO communication parameter
1403h 20h 4
th
receive PDO communication parameter
1600h 21h 1
st
receive PDO mapping parameter
1601h 21h 2
nd
receive PDO mapping parameter
1602h 21h 3
rd
receive PDO mapping parameter
1603h 21h 4
th
receive PDO mapping parameter
1800h 20h 1
st
transmit PDO communication parameter
1801h 20h 2
nd
transmit PDO communication parameter
1802h 10h 3
rd
transmit PDO communication parameter
1803h 20h 4
th
transmit PDO communication parameter
1A00h 21h 1
st
transmit PDO mapping parameter
1A01h 21h 2
nd
transmit PDO mapping parameter
1A02h 21h 3
rd
transmit PDO mapping parameter
1A03h 21h 4
th
transmit PDO mapping parameter
Data type “20h” is a record, which defines the PDO communication parameter, and it is of the following
format:
Sub-Index Type Meaning Notes
0h UNSIGNED8
Number of supported entries in the
record
Default: 2
1h UNSIGNED32 COB-ID
2h UNSIGNED8 transmit type Default: 255
3h UNSIGNED16 inhibit time TPDO only
4h UNSIGNED8 CMS priority group Default: 3
Data type “21h” is a record, which defines the PDO mapping parameter and it is of the following
format:
Sub-Index Type Meaning Notes
0h UNSIGNED8
Number of supported entries in the
record
Default: 2
1h
or
1h, 2h
UNSIGNED32
Structure consisting of mapped
object index (16 bit), sub-index (8
bits) and object data length in bits.
For example “20010010h” defines
object “2001h”, sub-index “0h”, and
data length of16 bits (=word).