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DVP-ES2/EX2/SS2/SA2/SX2/SE Operation Manual - Programming
7-10
receive PDOs are called PDO consumers.
The PDO is described by means of the “producer/consumer mode”. The data is transmitted
from one producer to one or many consumers. The data which can be transmitted are
limited to 1-byte data to 8-byte data. After the data is transmitted by the producer, the
consumer does not need to reply to the data. Every node in the network will detect the data
information transmitted by the transmission node, and decides whether to process the data
which is received.
Every PDO is described by two objects in the object dictionary: The PDO communication
parameters and the PDO mapping parameters
The PDO communication parameters: The COB-ID which will be used by PDO, the
transmission type, the prohibition time, and the cycle
of the counter
The PDO mapping parameters: They include the object list in an object dictionary. These
objects are mapped into the PDO, including the data length
(in bits). To explain the contents of the PDO, the producer
and the consumer have to understand the mapping.
The PDO transmission mode: synchronous and asynchronous
Synchronous: Synchronous periodic and synchronous non-periodic
Asynchronous: The PDO is transmitted when the data changes, or it is transmitted after a
trigger.
The transmission modes supported by are as follows.
Type PDO transmission
Periodic Non-periodic Synchronous Asynchronous RTR
0 X X
1 – 240 X X
254 X
255 X
Mode 0: The PDO information is transmitted only when the PDO data changes and the
synchronous signal comes.
Modes 1~240: One piece of PDO information is transmitted every 1~240 synchronous
signals.
Mode 254: The trigger is defined the manufacturer. The definition of the PLC is the same as
mode 255.
Mode 255: PDO is transmitted when the data changes, or it is transmitted after a trigger.
All the data in the PDO has to be mapped from the object dictionary. The following is an
example of the PDO mapping.
PDO_1
Application object C
zzh zzzzh
Application object B
yyh yyyyh
Application object A
xxh xxxxh
Object dictionary
xxxxh
zzzzh
yyyyh
8 xxh 3
16 zzh 2
8 yyh 1
3 0
PDO_1 mapping
Application object A
Application object C
Application object B