Sdo (Service Data Objects); Pdo (Process Data Object); Emcy (Emergency Object) - Delta C2000 series User Manual

SDO (Service Data Objects)

SDO is used to access the Object Dictionary in every CANopen node by Client/Server
model. One SDO has two COB-ID (request SDO and response SDO) to upload or
download data between two nodes. No data limit for SDOs to transfer data. But it needs to
transfer by segment when data exceeds 4 bytes with an end signal in the last segment.
The Object Dictionary (OD) is a group of objects in CANopen node. Every node has an OD
in the system, and OD contains all parameters describing the device and its network
behavior. The access path of OD is the index and sub-index, each object has a unique
index in OD, and has sub-index if necessary. The request and response frame structure of
SDO communication is shown as follows:

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
Cyclic
0
1-240
241-251
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.

EMCY (Emergency Object)

When errors occurred inside the hardware, an emergency object will be triggered an emergency object
will only be sent when an error is occurred. As long as there is nothing wrong with the hardware,
there will be no emergency object to be served as a warning of an error message.
Acyclic
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Chapter 15 CANopen Overview C2000 Series
PDO
Synchronous Asynchronous
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Reserved
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15-5
RTR only
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