Controllers - devices that control other Z-Wave devices.This means each node can be individually addressed giving you complete control of your own home automation system. On a single network (one Home ID) two nodes cannot have identical Node IDs. This is because the two networks are isolated from each other. Nodes with different Home IDs cannot communicate with each other, but they may have a similar Node ID. The Node ID has a length of 1 byte = 8 bits. The Node ID is the address of a single node in the network.
The Home ID is the common identification of all nodes belonging to one logical Z-Wave network.The Z-Wave protocol defines two identifications for the organisation of the network. Therefore, each type of “network” needs to have a defined protocol that allows the different nodes of one network to identify each other and to exclude messages from other radio sources.Įach node in the network also needs to have a unique identification to distinguish it from other nodes in the same network. The communication media for radio (wireless) is the air, which is also used by all sorts of different technologies - TV, Wi-Fi, mobile phones etc. In most cases this is a physical communication media like a cable. To be able to communicate with each other, the nodes need to have access to a common media or need to have “something in common”. Using Nodes for Successful CommunicationĪ network consists of at least two nodes. The number of unsuccessful attempts is also a good indicator of the network’s wireless connection quality. After three unsuccessful attempts the Z-Wave transceiver will give up and report a failure message to the user. A Z-Wave transceiver will try up to three-times to send a message while waiting for an ACK. The return receipt is called Acknowledge (ACK). This doesn’t guarantee that the message was delivered correctly, however, the sender will get an indication that a situation has changed, or an error has occurred.įigure 2 - communication with and without acknowledgment Z-Wave is the one of the most reliable wireless technologies, every command sent is acknowledged by the receiver which sends a return receipt to the sender. This can cause stability problems, unless the installation was planned and tested correctly. In a simple network, the sender gets no feedback on whether the message has been received and if the command has been executed correctly. In the case of a home automation network it could be due to interference or positioning the receiver too far away from the sender. In a mobile phone’s case, it could be due to poor reception. Similarly, wireless home automation technologies use the same principles to enable communication between sender and receiver nodes. You assume that it’s sent and will be received and read by the recipient. Rather like sending a text message, you can’t see how the information transfers from your phone to theirs. The Media Access (MAC) and Transport Layers Explained This layer will use additional nodes to re-send the message if the destination is outside of the “direct” range of the transmitting node. Routing Layer: Manages Z-Wave’s “Mesh” capabilities to maximise network range and ensure messages get to their destination node.The end user cannot influence this layer’s functions but the results of this layer are visible. Transport Layer: Controls message transfer, ensuring error-free communication between two wireless nodes.Media Access Layer (MAC): Controls the basic usage of the wireless hardware - these functions are invisible to the end user.The Z-Wave network layer controls how data is exchanged between different devices (nodes) on the network, it consists of three sub-layers. Application Layer: Defines which messages need to be handled by specific applications in order to accomplish particular tasks such as switching a light or changing the temperature of a heating device.This includes addressing, network organisation, routing, etc. Network Layer: Defines how control data is exchanged between two devices or nodes.
This includes frequency, encoding, hardware access, etc.