Linx Technologies HUM-xxx-DT - Manual (Page 11)

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Addressing
There are two addresses used by the modules; the module address and
the network ID. The module address is a 4 byte number that identifies the
specific module in the network. This number is unique to the module and
cannot be repeated within a network.
The network ID is a 4 byte number that is used to identify which network
the module is in. This is shared by all modules within the network.
Modules that have different network IDs can have the same module
address. No module should have the same module address and network
ID. If this happens, the first module that contacts the AP is accepted into
the network and the second is rejected and cannot communicate with the
AP.
Each module is programmed with a unique 4 byte serial number at the
factory. This can be used as the module address by reading it out through
the CDI and writing it back as the local address. The serial number cannot
be changed. This can ensure that every module in the system has a unique
address rather than having to track addresses separately.
If two networks are operating in proximity, then it is possible for modules to
hear transmissions from the other network. If the network ID in the received
packet does not match the module’s local network ID, then the packet is
ignored and discarded.
Each module can also report out the modules it is linked to in the network.
EDs only return the address of the AP. The AP outputs the addresses
for all of the EDs that it has joined and linked to in the network. This is
accomplished with a serial command through the module’s Command
Data Interface. This is a convenient way to quickly establish the entire
network from the AP.
The REs do not have the intelligence to record all of the modules in its
range. They respond with 0 associated modules.
Initialization and Joining
The module runs through an initialization routine when it is powered up. It
reads the operational configuration from its non-volatile memory and loads
them into it volatile memory. The volatile memory is lost when power is
removed, but it is faster to access so is better when the module is active.
The module initializes all of the routines with the configuration settings and
enters its device type, either AP, ED or RE.
Based on the device type setting, the module then begins the join and
linking process. The join process is how an ED or RE gains access to an
AP and joins a network. Once the module is joined, it sets up the link to the
AP so that it can communicate its data.
All of this happens automatically when power is applied. If an AP and
several EDs are brought online at the same time, the AP manages
communication until all EDs are joined. No intervention is required by the
user or an external microcontroller.
Once the initialization and join processes have been completed, the module
outputs an initialization complete message on the CMD_DATA_OUT line.
This is shown in Figure 56 in the Command Data Interface (CDI) Command
Set section. This process occurs when the module is first powered on and
when it wakes from sleep.
The CDI has commands for managing the modules associated with an
AP. These include returning a count of associated modules, the full list of
addresses of associated modules, and a command to delete a module
from the list. Once an ED is deleted from the list no communications can
occur until the module rejoins the network. This happens automatically
when the power is cycled to the ED or the reset command is issued.