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Node guard protocol
To ask for a node its state, the master sends :
700 +
nodeID
The node responds :
Examples
To ask for the node 5 its state, the master sends a CAN request (rtr = 1) : 705
The node 5 which is in stopped mode responds : 705 05
The master sends a NMT to put the node in pre-operational mode : 000 80 05
The master sends a new CAN request : 705
The node 5 which is now in pre-operational mode responds : 705 FF because the toggle = 1
1
0
700 +
nodeID
t
state
One byte
t : toggle 0,1,0,1....
state : 4 = stopped
5 = operational
7F = pre-operational
Heartbeat protocol
The node transmit cyclically its state, without the need of a request frame :
0
700 +
nodeID
0
state
One byte
state : 4 = stopped
5 = operational
7F = pre-operational
Examples
The node 5, in pre-operational mode sends cyclically : 705 7F
Beware : There is no toggle bit.
Bootup protocol
When a node enters in pre-operational mode after being in initializing mode, it sends :
00
0
700 +
nodeID