5. Access Procedure
48
Festo P.BE-CMMP-CO-SW-EN 0708NH
All other state transitions are performed automatically by the motor controller, e.g.
because the initialisation is completed.
In the
NI
parameter, the node number of the motor regulator must be specified, or zero if
all nodes in the network are to be addressed (broadcast). Depending on the NMT status,
certain communication objects cannot be used: So, for example, it is absolutely necessary
to place the NMT status to
Operational
, so that the controller sends PDOs.
Name
Meaning
SDO
PDO
NMT
Reset
Application
No Communication. All CAN objects are reset to their reset values
(application parameter set) reset
-
-
-
Reset
Communication
No communication The CAN controller is newly initialised.
-
-
-
Initialising
Condition after hardware reset. Resetting of the CAN node, sending
of the bootup message
-
-
-
Pre-operational Communication via SDOs possible PDOs not active
(no sending / evaluating)
X
-
X
Operational
Communication via SDOs possible All PDOs active
(sending / evaluating)
X
X
X
Stopped
No communication except for heartbeating
-
-
X
Tab. 5.3: NMT state Machine
NMT telegrams must not be sent in a burst (immediately one after
another)!
At least twice the position controller cycle time must lie between
two consecutive NMT messages on the bus (also for different
nodes!) for the motor controller to process the NMT messages
correctly.
If necessary, the NMT command "Reset Application" is delayed
until an ongoing storage process is completed, since otherwise the
storage process would remain incomplete (defective parameter
set).
The delay can lie in the range of some seconds.
The communication status must be set to
operational
for the
controller to transmit and receive PDOs.
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