Z-Wave
From HomeSeer
Z-Wave is a purely-RF mesh network protocol. All devices must be added to the network via the primary controller; this sets up security and routing data. Because of the latter, devices should not be moved after adding them; if that is required, the device should either be deleted and re-added, or the "Optimize Network" method in HomeSeer should be used.
Z-Wave networks are limited to 232 devices, just a bit less than the 256 supported by an X-10 network across all house codes. This is not typically considered an issue for Home Automation, but may be for industrial uses of the same technologies.
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[edit] Compared to X10
X-10 is primarily a PLC (powerline) protocol, with an ancillary RF protocol that devices such as the RR501 can transcode from the RF to the PLC. Being older and PLC-based, X-10 suffers in comparison to Z-Wave as slower and less reliable.
But because Z-Wave routes messages specifically to the destination device, other devices cannot necessarily "listen in" on it. Additionally, because all devices must be members of the network, a remote control must be taught the network (or be the primary controller, in which case it teaches the rest of the network.) The net result of this is that we currently do not have any Z-Wave equivalents to the inexpensive (sub-$25) X10 PalmPad or little remotes. The closest current similation is to use a "secondary controller", dedicate a Z-Wave module (e.g. relay module) to serve as a proxy for the command, and when that device's status changes, launch the desired HomeSeer event. Set the remote "controller" to control that module.
[edit] Compared to Insteon
Unlike Z-Wave, Insteon can support both RF and PLC. In practice, most contemporary devices are purely PLC devices. While Z-Wave uses routing tables to get a message to a module that is otherwise out of range, Insteon broadcasts the message indiscriminately, which requires it limit hops to prevent "data storms". Z-Wave doesn't have this issue. On the other hand, Insteon devices don't need to be formally "added" to the network either.
Insteon supports thousands of devices on a network, compared to the 232 devices supported by Z-Wave.
Z-Wave has a theoretical advantage in having come to market in 2003 versus 2005 for Insteon (which even then had a rough start), but Insteon is supported by their parent, SmartHome, which is probably the dominant home automation outlet in the U.S.
[edit] Compared to ZigBee
ZigBee is currently a non-player in the Home Automation field, but is regularly listed as a primary competitor to Z-Wave. ZigBee is an 802.15.4 technology using the 2.4GHz frequency rather than the 900MHz used by Z-Wave (and Insteon); this results in significantly lower "penetration" and has necessitated some redesign for home automation. ZigBee has the advantage of having been a Committee/Alliance type project as well as being built on top of the 802.15.4 protocol, and therefore is less prone to a single supplier and also does not require a license fee. The large partners in ZigBee, such as Intel, Cisco, T.I. and Motorola, are not typical Home Automation players. ZigBee protcol devices are extremely rare currently.
ZigBee supports thousands of devices on a network, compared to the 232 devices supported by Z-Wave.
[edit] General Comparisons
Z-Wave is currently the best selling RF home automation system. Note that this excludes RF-bridged Insteon and X-10 devices, which are inherently PLC.
Unlike X10, but currently very much like Insteon, Z-Wave is dependent on a single provider. In this case, all Z-Wave chips come from Zensys.
Zensys is occasionally caught masquerading their marketing department as independent analysts. See, for example, this CNET comparison of ZigBee and Z-Wave and then check out who the author was. (Hint: the "VP of Alliances" at ZenSys and former Z-Wave Alliance Board Member for Danfoss A/S.) Such stunts are typically reserved for those losing in the struggle for survival, a description that doesn't otherwise appear to fit.
But that said, Z-Wave appears anecdotally to be far more reliable than X-10 or Insteon. Because neither [UPB] nor ZigBee have much current penetration, their reliability is hard to gauge, but UPB is a powerline protocol prone to the same noise problems afflicting X10 and Insteon.
[edit] Feature: Associations
Z-Wave devices can support "associations". An "association" allows the given device (the source) to send a command to other devices (the destination) when specific events occur in the source device. Typically, the event that causes the command to be sent is a change in state, such as turning on, and the command sent is usually the same event type. For example, a BASIC command class ON signal will turn on virtually all Z-Wave devices. When the source device is turned ON and it has node(s) that it is associated with, then it will usually send a BASIC ON command to the destination nodes. The original ACT HomePro switches, for example, support both notifying HomeSeer (when so associated) and also controlling other Z-Wave devices. This allows the creation of virtual 3-way circuits controlling multiple lights, for example, without any HomeSeer events. Devices only send the commands to their associated devices (nodes). (Of course an event in HomeSeer triggered on "State Set" would do the same thing, but would also require creating a trigger based on each switch.)
Not all devices support associations, and therefore, instant status. For example, the Leviton ViziaRF lamp and relay module do, but the Intermatic lamp and relay module do not. So the ViziaRF line can provide instant status change notifications to HomeSeer when so associated, but the Intermatics cannot. (This also means the Intermatics are not capable of serving as "virtual devices". Because they cannot be "associated", they cannot notify HomeSeer of a received "set". In other words, HomeSeer can poll to see if a device turned from "Off" to "On", but it cannot determine if a device that was already "Off" was sent another "Off". So not only would a status change have a polling latency, but only actual state changes, not state commands, would be able to trigger events in HomeSeer.)
Even devices that do support Associations may be inconsistent in the application. For example, if a Leviton ViziaRF lamp or relay module is toggled using local control, it will alert the associated devices. But if they are toggled by a secondary controller such as the Intermatic HA09, they will not... with the surprise effect that HomeSeer has no idea what the status is until the next scheduled polling cycle! This is by design, however, to avoid circular association references. Both Cooper and Leviton avoid circular association references by not sending commands to associated devices if their state changed as a result of an incoming Z-Wave command - they only transmit the associated command when they are operated locally. #Note 1
[edit] Note
- Note that while the Cooper and some Leviton devices do not transmit associated commands when they receive a Z-Wave command, they also support the HAIL class, and so when they receive a Z-Wave command that changes their state, they can send a HAIL command to node(s) associated in a special association group. HomeSeer uses this to then immediately query the device for its current level so that events can be immediately triggered.
[edit] Specifications
- 900MHz
- Technically 908.42MHz in U.S., 868.42MHz in Europe
- Mesh network with routing
- No master node, but all devices must be added (or removed) via master controller.
- Supports 232 devices, including the master controller.
