During SynqNet network initialization, the network is discovered, the topology is tested for an exact match to the expected topology, the network is transitioned to cyclic operation (SYNQ mode), and the nodes are initialized. Under certain conditions, before transitioning to SYNQ mode, the controller’s internal buffers will need to be dynamically allocated.
The network initialization steps are shared between the MPI and the Controller. The flowchart below shows the initialization process. The column on the left shows the steps performed by the controller and the two columns on the right show those steps performed by the MPI.
There are two initialization routines that are used for Network Initialization:
Default Network Initialization
– This routine is used if the network topology has NOT been saved to flash memory. The network is configured and brought up to SYNQ mode in a safe, default configuration.
Automatic Network Initialization
– This routine is used if the network topology has been saved to the controller’s flash memory. When the controller is powered-on (or reset), the controller uses previously saved network configurations to initiate SYNQ mode operation. As a safety check, the discovered network will not transition to SYNQ mode unless the topology information matches the information stored in the controller's flash memory.
Power-On / Reset
After the initial power-on or controller reset, the controller does not know what nodes are connected to the network. Network topology information is loaded into the controller’s dynamic memory from flash memory.
After a network shutdown, the network topology configuration from the last initialization remains in the controller’s dynamic memory. Upon initialization this remaining topology information is used to compare against the discovered topology.
The controller resets all nodes on the network to an undiscovered state, collects information about the current network topology, and sequentially enumerates each node. At this point the controller is in ASYNQ mode. See SynqNet Discovery section for more information.
SynqNet Topology Test
This test uses the network topology information discovered during SynqNet Discovery and compares it with the topology information stored in the controller’s dynamic memory. The controller cannot invoke Automatic Initialization Routine unless an exact match is found. For details regarding match criteria please see the SynqNet Topology Test section.
Default Initialization Routine
This routine is invoked when there is no topology information available in controller memory. See Default Initialization Routine for more information.
Automatic Initialization Routine
This routine initializes a “known” network with preconfigured network settings previously written to controller’s memory. See Automatic Initialization Routine for more information.