COMMUNICATION OBJECTS DESCRIPTION
✓
NOTE!
The period of the SYNC telegrams must be programmed in the producer according to the transmission
rate and the number of synchronous PDOs to be transmitted. There must be enough time for the
transmission of these objects, and it is also recommended that there is a tolerance to make it possible
the transmission of asynchronous messages, such as EMCY, asynchronous PDOs and SDOs.
8.5 NETWORK MANAGEMENT - NMT
The network management object is responsible for a series of services that control the communication of the device
in a CANopen network. For this object, the services of node control and error control are available (using Node
Guarding or Heartbeat).
8.5.1 Slave State Control
With respect to the communication, a CANopen network device can be described by the following state machine:
Power On
Initialization
Pre-operational
Operational
Stopped
(1)
(2)
(3)
(4)
(5)
(4)
(3)
(5)
(6,7)
Figure 8.4:
CANopen node state diagram
Table 8.10:
Transitions Description
Transition
Description
1
The device is switched on and initiates the initialization (automatic)
2
Initialization concluded, it goes to the preoperational state (automatic)
3
It receives the Start Node command for entering the operational state
4
It receives the Enter Pre-Operational command, and goes to the preoperational state
5
It receives the Stop Node command for entering the stopped state
6
It receives the Reset Node command, when it executes the device complete reset
7
It receives the Reset Communication command, when it reinitializes the object values and the CANopen
device communication
During the initialization the Node-ID is defined, the objects are created and the interface with the CAN network is
configured. Communication with the device is not possible during this stage, which is concluded automatically. At
the end of this stage the slave sends to the network a telegram of the Boot-up Object, used only to indicate that
the initialization has been concluded and that the slave has entered the preoperational state. This telegram has the
identifier 700h + Node-ID, and only one data byte with value equal to 0 (zero).
In the preoperational state it is already possible to communicate with the slave. But its PDOs are not yet available
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