AmI Taxonomy AmI Taxonomy Network Characteristics of the - PDF document

AmI Taxonomy file:///D:/Mirror/elite/Didattica/Laurea/01PRD Ambient Intelligence/sl... AmI Taxonomy AmI Taxonomy Network Characteristics of the technologies allowing devices to communicate an collaborate in the exchange of information. Infrastructure How the devices communicate. Wired All devices are connected trough a set of wires. Depending on the protocol, we may use 2 wires or more. Examples: KNX, bTicino MyOpen, ModBus Powerline Re-uses the power lines for data communication, by modulating signals that are superimposed to the electric AC supply. Examples: Lonworks, Echelon (e.g. the ENEL meter), X10 Wireless Uses radio frequencies to exchange data. Devices need not be connected for communicating. They may need to be connected for power supply. Examples: Z-Wave, ZigBee, Wi-Fi, Bluetooh, 433Mhz, ... Mixed 1 di 9 08/05/2014 14:50

AmI Taxonomy file:///D:/Mirror/elite/Didattica/Laurea/01PRD Ambient Intelligence/sl... Some technologies may allow a mix of different connection methods. Mainly, wired technologies that allow for wireless extensions. Also, Wireless technologies that allow routing through a physical link. Examples: KNX. ModBus Topology The set of physical paths that are followed by communication messages. Bus One flat shared infrastructure where every node may send information to every other node directly, without intermediaries. Routed Special nodes are used to route and forward messages between different segments of the network. Example: in ZigBee and Z-Wave, powered devices may act as routers. Mesh Messages may be routed through any device, and are relayed until they reach the destination. Often, the mesh is dynamic and may be reconfigured (automatically or programmatically) according to device locations, and signal strength). Example: practically all wireless protocols Star All devices connect to one specific central node and may exchange data only with that node. Logical Hierarchy What is the flow of communications among nodes. Master-slave Only one "central" node (master) may contact all other nodes (devices, slaves). The master may be fixed, or may change over time (but only one master at a time must be active). Examples: ModBus, RFID, USB, CAN, ... Multi-master A master-slave hierarchy where more than one node may play the role of the master, simultaneously. Peer to peer All nodes in the network play the same role. Each of them may send/receive messages to any other node. Examples: IP-based networks, KNX Coordinator + nodes Mainly peer to peer network (nodes may communicate directly), where one node has a distinguished role of "coordinator" of the network (that has some unique and specific services and capabilities). The coordinator may be needed to keep the list of registered devices, or to allow devices to join the network, or to manage device configuration, etc. Examples: KNX, Z-Wave, ZigBee. Controller/Master In master-slave or coordinated networks, what is the nature of the controller or master node. Not needed Special node (boundary) One special device in the network takes the role of a controller or master. Very often, this device is also at the "boundary" with external infrastructure: it may be connected to the LAN, it may offer serial/USB ports. In these cases, all communications to/from the devices will always be routed by the controller, that thus acts as a gateway, too. Examples: ModBus, MyOpen, KNX Any node Any node (e.g. through election mechanisms) may take the role of controller. Examples: SMB Addressing 2 di 9 08/05/2014 14:50

AmI Taxonomy file:///D:/Mirror/elite/Didattica/Laurea/01PRD Ambient Intelligence/sl... The mechanism by which each device can be identified uniquely in the network, and messages may find the correct destination. Device address Each physical device has one specific address. The address may be hardware-defined (e.g. MAC addresses in WiFi or Bluetooth, or jumpers in MyOpen), or software-assigned (e.g., IP addresses in DHCP). Serial number Network address Group address In some networks, we may define addresses that reach "groups" of devices. Similar to "multicast" messages. Groups may be formed by the controller node, or may be published by the devices. Sub-function address Some devices include multiple sub-devices, that are separately addressable. Example: a bank of 8 relays (KNX "endpoints"), ModBus register ranges Discovery Capability of the network of determining which devices are currently connected, and what is the nature of those devices. Discoverable The network has a discovery capability. In some cases it needs to be activated with a special command (e.g. KNX). In other cases the list of devices is always kept updated (e.g., Z-Wave). Non discoverable No discovery available. To contact devices, you must know (beforehand) their addresses (at least). Example: MyOpen, ModBus Communication When information messages are exchanged among devices/nodes. Polling Nodes may be queried by the controller/master. Nodes will never send any communication, unless explicitly queried. To have an updated state of the network, usually a periodic "polling cycle" in needed, where each devices is queried at regular time intervals. Examples: ModBus Synchronous Devices can be instructed to send their status (or their measurements) at regular intervals (e.g. a new data sample every 200ms). In some cases, the temporal sequence of communications is predetermined (i.e., there is a global "time wheel" and each device has one specific "time slot" in which it transmits). This is usually associated with tight timing constraints. In other cases, the device decides to transmit on its own schedule, and accesses the network at that time. Examples: CAN Asynchronous (events) Devices may transmit data at any time. This is often associated with transmission of information related to specific "events": a button has been pressed, a sensor has crossed a threshold, some condition has been met, etc. Asynchronous event sending may also be combined with periodical synchronous updates (e.g., send updates every 30 minutes, but send an update immediately if the temperature has changed more than 1°C). Example: Z-Wave sensors. Data handling What is the conceptual data model uses to represent and exchange information with the device. Register-based 3 di 9 08/05/2014 14:50

AmI Taxonomy file:///D:/Mirror/elite/Didattica/Laurea/01PRD Ambient Intelligence/sl... Devices offer a bank of registers (usually, 8-bit). Each register (or pair/quadruple) or register encodes a specific value. Values may be read-only (e.g., for sensor values), or write-only or read-write (e.g., for sending commands or configuring the device). The meaning of the registers must be known to the programmer (e.g., through the device data sheets). Example: ModBus Command-based Devices can be contacted by sending commands (usually, in an asynchronous way). Commands may have parameters. Commands may change the device status, cause some actions, or modify device configuration. Commands may also be used to query for device values. Examples: KNX, MyOpen, Z-Wave Notification-based The device will send (usually in an asynchronous way) some message (event, notification), according to its internal strategies and configuration. Examples: MyOpen, Z-Wave Transport Protocol The organization of binary messages, their format, their exchange mechanisms. At this level, we are not concerned with the meaning of messages, but just with their encoding and transmission. Open standard The format of data and messages is public, is often "blessed" by some standardization organization, and everybody is free to read, write, and develop new components using those messages. Examples: ZigBee (TCP)/IP Data transmission is based on the IP (Internet Protocol). Both bare-IP or TCP-over-IP are used. This usually requires more powerful nodes and may open the device to the "Internet of Things" Examples: surveillance infrastructures, industrial internet, internet of things, ... Proprietary standard The format of data and messages is known, and has been defined by a company (or by a closed group of companies). Developing new components using the standards may be: forbidden -or- requiring a certification -or- allowed. Usually it requires signing some agreement or joining some association. Examples: MyOpen, KNX Generally available Even if the standard is controlled by some commercial entity(ies), its specification is public. Example: MyOpen Restricted availability Accessing the technical documentation requires joining some association and/or signing some agreement. Example: KNX Ad hoc Proprietary system, usually developed by one company, that uses custom methods, protocols, and data formats. Such protocols are not published, and usually components must be developed (or adapted) by the company. Examples: too many. Application protocol The high-level format of messages (where the messages assume an application-defined meaning). An application protocol may usually be applied on-top-of different transport protocols. Open standard 4 di 9 08/05/2014 14:50