OD (Object Dictionary):
This is an ordered, predefined group of objects that can be accessed via the network, with each object addressed by a 16-bit index and an 8-bit sub-index. The range of a node’s object dictionary is from 0X1000 to 0X9FFF.
COB-ID (Communication Object Identifier):
This is the message frame ID of the CANopen communication object, which is the 11-bit ID of the CAN message, consisting of a 4-bit function code and a 7-bit node ID.
Node-ID:
This is the node address in the CANopen network, with a maximum node count of 128 as specified in CAN2.0A.
NMT (Network Management Object):
This is used to control the network behavior of CANopen slave devices, including initializing, starting, resetting, or stopping the devices.
PDO (Process Data Object):
This is used to transmit real-time data. Both parties define the data receiving and sending areas before transmission, and during data exchange, the relevant data is directly sent to the other party’s data receiving area, reducing the inquiry time of a question-and-answer style and greatly improving the efficiency of bus communication. Each PDO includes two parts: PDO communication parameters and PDO mapping parameters.
SDO (Service Data Object):
This is used to transmit low-priority data, typically used for configuring and managing slave devices, such as setting electronic gear ratios and zero-return modes. This data transmission is similar to Modbus, where the master sends a request, and the slave must return a data response.
Node Guarding:
This is where the master monitors the current status of the slave. Node guarding adopts a master-slave model. The master sends node guarding remote frames at regular intervals (Guard Time), and the slave must respond. If the master does not receive a return message from the slave within the time of Guard Time x Life Time Factor, it is considered that the slave is offline.
Guard Time (100CH): Node guarding time
Life Time Factor (100DH): Lifetime factor
Heartbeat:
This is used to check whether network members are functioning properly. The heartbeat adopts a producer-consumer model. CANopen devices can periodically send heartbeat messages based on the producer heartbeat interval time set in 1017H (also called production time). Nodes on the network with heartbeat consumption functions monitor the producer based on the consumer time set in 1016H. If the corresponding node’s heartbeat is not received within the consumer heartbeat time, it is considered that the node has failed.
EDS (Electronic Data Sheet):
This describes the object dictionary and other information of the device.
DCF (Device Configuration File):
This is the archived configuration data file for the CAN network.
DS301 (CiA301):
This is the general basic protocol for the CANopen application layer, describing the main form of the object dictionary, and this protocol is applicable to all CANopen devices.
DS4 (Device Profile):
This is a supplement and extension to the DS301 protocol for different types of devices.
DS401: I/O Device Profile
DS402: Drive Device Profile
DS403: HMI Device Profile
DS404: Sensor/Regulator Device Profile
DS405: Programmable Controller Profile
DS406: Encoder Profile
…
Standard Frame:
11-bit identifier
Extended Frame:
29-bit identifier
Remote Frame:
This is determined by the RTR (Remote Transmission Request) bit, where RTR=1 indicates a remote frame.