Module for adding and removing Z-Wave nodes

In Z-Wave the term "inclusions" means two things:

1. Adding a new Z-Wave device to the Z-Wave Network
2. Removing a Z-Wave device to the Z-Wave Network

In practice though it is more common to speak about adding a Z-Wave node in the context of "including" and removing an Z-Wave mode in the context of "excluding." This module provides functionality for working will all contexts of inclusion, both adding and removing.

Adding a Z-Wave Node (including)

When adding a device that does not required any security authentication is as simple as calling Grizzly.Inclusions.add_node/0.

iex> Grizzly.Inclusions.add_node()
:ok

After starting the inclusion on the controller, which the above function does, you can then put your device into inclusion as well. From here the new device and your controller will communicate and if all goes well you should receive a message in the form of {:grizzly, :inclusion, NodeAddStatus} where the the NodeAddStatus is a Z-Wave command the contains information about the inclusion status (status, node id, supported command classes, security levels, etc.). See Grizzly.ZWave.Commands.NodeAddStatus for more information about the values in that command. For example:

defmodule MyInclusionServer do
  use GenServer

  require Logger

  alias Grizzly.Inclusions
  alias Grizzly.ZWave.Command

  def start_link(_) do
    GenServer.start_link(__MODULE__, nil)
  end

  def add_node(pid) do
    GenServer.call(pid, :add_node)
  end

  def init(_) do
    {:ok, nil}
  end

  def handle_call(:add_node, _from, state) do
    :ok = Inclusions.add_node()
    {:reply, :ok, state}
  end

  def handle_info({:grizzly, :inclusion, report}, state) do
    case Command.param!(report.command, :status) do
      :done ->
        node_id = Command.param!(report.command, :node_id)
        Logger.info("Node added with id: " <> node_id)

      :failed ->
        Logger.warning("Adding node failed :(")

      :security_failed ->
        node_id = Command.param!(report.command, :node_id)
        Logger.warning("Node added with id: " <> node_id <> "but the security failed")
    end

    {:noreply, state}
  end
end

Stop Adding a Node

If you need you need to stop trying to add a node to the Z-Wave network you can use the Grizzly.Inclusions.remove_node/0 function.

This should stop the controller from trying to add a node and return it to a normal functions state.

Security

There are five security levels in Z-Wave: unsecured, S0, S2 unauthenticated, S2 authenticated, and S2 access control. The first 2 requires nothing special from the calling process to able to use, as the controller and the including node will figure out which security scheme to use.

S2

The process of adding an S2 device is a little more involved. The process is the same up until right after you put the including node into the inclusion mode. At that point including will request security keys, which really means it tells you which S2 security scheme it supports. You then use the Grizzly.Inclusions.grant_keys/1 function to pass a list of allowed security schemes.

After that the node will response with a NodeAddDSKReport where it reports the DSK and something called the :dsk_input_length. If the input length is 0, that means it is trying to do S2 unauthenticated inclusion. You can just call Grizzly.Inclusions.set_input_dsk/0 function and the rest of the inclusion process should continue until complete.

If the :dsk_input_length has number, normally will be 2 that means the including device is requesting a 5 digit digit pin that is normally found on a label somewhere on the physical device it.

From here you can call Grizzly.Inclusions.set_input_dsk/1 with the 5 digit integer as the argument. The inclusion process should continue until complete.

Removing a Z-Wave Node (excluding)

To remove a Z-Wave node from the network the Grizzly.Inclusions.remove_node/0 will start an inclusion process for removing a Z-Wave node. After calling this function you can place your device into the inclusion (normally the same way you included the device is the way the device is excluded) mode. At the end of the exclusion the NodeRemoveStatus command is received and can be inspected for success of failure.

Removed Node ID 0?

Any Z-Wave controller can excluded a device from another controller. In practice this means your Z-Wave controller can make a device "forget" the controller it is currently attached to. Most the time Z-Wave products will have you excluded your device and then included just to make sure the including node isn't connected to another Z-Wave controller.

When this happens you will a successful NodeRemoveStatusReport but the node id will be 0. This is consider successful and most the time intend.

Stopping Remove Node Process

To stop the removal inclusion process on your controller you can call the Grizzly.Inclusions.remove_node_stop/0 function.

Inclusion Handler

To tie into the inclusion process we default to sending messages to the calling process. However, there is a better way to tie into this system.

When starting any inclusion process you can pass the :handler option which can be either another pid or a module that implements the Grizzly.InclusionHandler behaviour, or a tuple with the module and callback arguments.

A basic implementation might look like:

defmodule MyApp.InclusionHandler do
  @behaviour Grizzly.InclusionHandler

  require Logger

  def handle_report(report, opts) do
    Logger.info("Got command: " <> report.command.name <> " with callback arguments " <> inspect opts)
    :ok
  end
end

This is recommended for applications using Grizzly over a GenServer that wraps Grizzly.Inclusions.