
3 Basics | IL•1F CANopen DS301 |
NMT message The NMT services for device control are transmitted as unconfirmed messages with the COB ID = 0 . By default, they have the highest priority on the CAN bus.
The data frame of the NMT device service consists of 2 bytes.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Byte 0 | 1 |
|
|
|
| NMT- |
| |||||
| NMT- |
|
|
|
|
|
|
|
|
|
| ||||||||
|
|
|
|
|
|
|
|
|
| Slave |
| ||||||||
| Master |
|
|
| 0 |
|
| 01 |
| 00 |
|
|
|
|
|
| |||
|
|
|
|
|
|
| |||||||||||||
|
|
|
|
|
| ||||||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| NMT- |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Slave |
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| ||
|
|
|
|
|
|
|
|
|
|
|
|
|
| ||||||
|
|
|
|
|
| Command specifier |
|
|
|
| |||||||||
|
|
|
|
|
|
|
| NMT- |
| ||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Slave |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Figure 3.30 NMT message
The first byte, the "Command specifier", indicates the NMT service used.
Command Specifier | NMT service | Transition |
1 (01h) | Start remote node | A |
2 (02h) | Stop remote node | B |
128 (80h) | Enter | C |
129 (81h) | Reset node | D |
130 (82h) | Reset communication | E |
The second byte addresses the recipient of an NMT message with a node address between 1 and 127 (7Fh). A message with the node ad- dress "0" is directed to all NMT slaves.
3.6.2NMT services for connection monitoring
Connection monitoring monitors the communication status of network devices, so a response to the failure of a device or an interruption in the network is possible.
Three NMT services for connection monitoring are available:
•"Node guarding" for monitoring the connection of an NMT slave
•"Life guarding" for monitoring the connection of an NMT master
3.6.2.1Node/Life guarding
COB ID Communication object NMT error control
COB ID = function code NMTerror control (700h) +
0198441113586,
48 | Fieldbus interface |