E-8
E.1.4.3 PDO (Process Data Object)
PDO communication can be described by the producer/consumer model. Each node
of the network will listen to the messages of the transmission node and distinguish if
the message has to be processed or not after receiving the message. PDO can be
transmitted from one device to one another device or to many other devices.
Every PDO has two PDO services: a TxPDO and a RxPDO. PDOs are transmitted in a
non-confirmed mode.
PDO Transmission type is defined in the PDO communication parameter index (1400h
for the 1st RxPDO or 1800h for the 1st TxPDO), and all transmission types are listed in
the following table:
Type Number
PDO
Cyclic
Acyclic Synchronous Asynchronous
RTR only
0
○
○
1-240
○
○
241-251 Reserved
252
○
○
253
○
○
254
○
255
○
Type number 1-240 indicates the number of SYNC message between two PDO
transmissions.
Type number 252 indicates the data is updated (but not sent) immediately after
receiving SYNC.
Type number 253 indicates the data is updated immediately after receiving RTR.
Type number 254: Delta CANopen doesn’t support this transmission format.
Type number 255 indicates the data is asynchronous transmission.
All PDO transmission data must be mapped to index via Object Dictionary.
