User Manual of iSV2-CAN Servo
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At the end of initialization state the device sends a boot-up message and goes directly to Pre-Operational state.
NMT state pre-operational
In Pre-Operational state, the communication using SDO messages is possible. PDO message are not yet
defined and therefore communication using these message is not allowed. The device will pass to Operational
message after receiving a NMT start node command.
Normally the master puts a node in Pre-Operational state during the set-up and configuration of device
parameters.
NMT state operational
In Operational state all kind of messages are active, even PDO messages.
NMT state stopped
When entering in Stopped state, the device is forced to stop all communications with the exception of the
NMT commands. (Node Guarding & Life Guarding).
NMT states and communication object relation
Following table shows the relation between communication states and communication objects. Services on the
listed communication objects may only be executed if the devices involved in the communication are in the
appropriate communication states
5.3.1 NMT services
The structure of each NMT service command is as follows:
COB-ID(hex)
Number of Bytes
Data field
Byte 0
Byte 1
0x000
2
Command specifier
Node-ID
The possible NMT services commands are the followings:
Command specifier(hex)
Command description
01
Start remote node
02
Stop remote node
80
Enter pre-operational
81
Reset node
82
Reset communication
Example of Node-ID=1 NTM services:
COB-ID(hex) Number of Bytes
Data(hex)
Description
000
2
80 01
NMT Host commands node 1 into Pre-Operational state
000
2
01 01
NMT Host commands node 1 into Operational state
000
2
02 01
NMT Host commands node 1 into Pre-Operational state
000
2
82 01
NMT Host commands a communication reset to node 1
701
1
00
Node 1 response with a boot-up message
5.3.1 NMT error control
Protocol node guarding
The NMT Master can monitor the communication status of each node using the Node Guarding protocol.
During node guarding, a controller is polled periodically and is expected to respond with its communication
state within a pre-defined time frame. Note that responses indicating an acceptable state will alternate between