7 Format Description of CANopen Message
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7 Format Description of CANopen Message
7.1 NMT Module Control Message
Only the NMT master can send the NMT Module ControlNMT message. Table 7-1
shows the message format. COB-ID is xed to 0x000, and Data0 is the command word
and occupies one byte, as shown in Table 7-2. Data1 is the CANopen network device
address, and occupies one byte; when Data1 is 0, this message is broadcast to all slaves
in the network.
For example, to set the device with the address "6" to the operational state, the
command "0x000 0x01 0x06" is sent.
Table 7-1 NMT module ControlNMT message format
COB-ID RTR Data0 Data1
0x000 0 Command word Node ID
Table 7-2 Command word of NMT Module ControlNMT message
Command Word Description
0x01 Start Remote Node
0x02
Stop Remote Node
0x80
Enter Pre-operational State
0x81
Reset Node
0x82
Reset Communication
7.2 NodeGuarding Message
With the NodeGuarding service, the NMT master can check the current state of all
nodes. This service can be used to detect whether data transmission of the nodes is
available.
The standard protocol objects 0x100C and 0x100D respectively set the guard time and
the guard time multiplicative factor, which together determine the node guarding time
period.
Table 7-3 is the remote frame sent by the NMT master.
Table 7-3 Frame sent by the NMT master
COB-ID RTR
0x700+Node-ID 1
Table 7-4 is the response message returned by the NMT slave. Table 7-5 shows the
status word one-byte format.
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