Z-Wave Network

Whats the difference between Z-Wave and Z-Wave Plus?

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There is a lot of confusion between Z-Wave Plus and older non-Plus devices.

Z-Wave_Plus_Badge_RGB_v3.1A product that is Z-Wave Plus means it has passed a rigorous certification process and thus is likely to be more reliable and have fewer issues than non-Plus devices. All Z-Wave devices are 100% interoperable and backwards compatible so a Z-Wave Plus device can communicate with any non-Plus device without issue. If you have a choice between a Z-Wave Plus device and a non-Plus device, I recommend you choose the Z-Wave Plus device because the Plus device will work better.

Z-Wave History Lesson

The timeline shows the technology trajectory that Z-Wave has traveled since its inception in 2002.ZWaveTimeLineThe timeline shows the constant improvement and evolution of Z-Wave. Initially the data rate was only 9600 bits per second. This was fast enough to turn a light or two on or off but as things progressed and you want to slowly change the color of a dozen or more bulbs, then you need a faster data rate. Thus, the increase to 40K with the 300 series and 100K with the 500 series. There are many other enhancements along the way including longer range, better RF sensitivity, lower power, more peripherals and in particular the AES encryption engine. The amazing thing though all of these improvements is that they have all remained 100% backward compatible. Even the latest chips can talk to the early 100 series chips. Granted it is only at the slower 9600 bps but it still works! So the lamp dimmer you bought in 2004 is still able to talk to the latest SmartThings hub.

The Curse of the Even Series

Z-Wave has had some mistakes along the way, after all no one is perfect. Much like the Star Trek Movies, all of the even series chips were flawed and quickly obsoleted. The developers became so fearful of the curse of the even series they skipped the 600 series and jumped straight to 700. The 200 series chips were simply buggy. Period. They had some significant power issues making them difficult to use as a battery powered device among other problems. The flaws were quickly fixed and the series replaced with the largely firmware compatible 300 series which had a long and plentiful life. Many 300 series devices are still in the market though the chips have reached end-of-life so there are limited inventories left. A small number of 300 series chip based devices are Z-Wave Plus – but that number is quite small and there are probably none left on the shelves though you could have one installed in your home. Fortunately, as we’ve seen they are all completely interoperable so no problem there.

The 400 series suffered from a marketing mistake early on – the memory that holds the firmware is One-Time-Programmable (OTP). This means the firmware cannot be updated – EVER. You burn it once, and pray it is good. This is a nightmare for developers as they have to replace the chip every time they make a new firmware build, which they typically do hundreds of times per day. While the OTP saves a fraction of cent in the cost of the chip, the drawbacks far outweigh that tiny cost.  Fortunately we developers didn’t have long to wait and the 400 series was replaced with the 500 series. The 500 series had plenty of FLASH and added the ability to update the firmware in the device even after it is installed in the field using a technique called Over-The-Air (OTA) firmware update.

Z-Wave Security – AES Encryption

One of the most important IoT devices is a door lock. Naturally, a door lock needs to be secure. Up until 2008, Z-Wave was “in the clear” meaning it wasn’t secure at all. The Security Command Class was added to encrypt all communication with banking quality AES-128 encryption which makes Z-Wave secure – or so the Z-Wave developers thought.

In 2013 it was widely published that the Z-Wave security has a weakness when a device is first joined to a network. During that process, the encryption “key” is sent to the device over the radio and it is encrypted, but the encryption key is 128 bits of 0. Since the encryption key is all zero, it is possible for someone with very sophisticated equipment to “sniff” the radio data and thus obtain the key to every secure device in the network. While this is a security hole, it requires a lot of equipment on-site at the short time when the user is adding a secure device to the network. Much easier for a burglar to throw a brick thru a window to gain access vs. hacking a Z-Wave door lock. But Z-Wave had to counter with an improvement and they did just that in 2015 – with the updated Security S2 command class.

Security S2 adds full diffe-hellman symmetric encryption to the key exchange. A number of performance improvements were also made which enables battery powered devices to be secure without spending extra time exchanging secrets back and forth. All devices certified after April 2017 are required to support Security S2.

The question of Z-Wave Plus vs. Non-Plus however is independent of Security. Since new devices have to implement Security and they are Z-Wave Plus certified, it seems like the two go together but in reality they are independent. But all new devices will have both which is good. Fortunately support for Security S2 isn’t required to be supported by Hub vendors like SmartThings, Vera, HomeSeer, etc. They will need to add support but all your older non-secure devices will remain 100% backward compatible.

The Future

Z-Wave continues to evolve and improve but continues to remain 100% backward compatible all the way back to 2002 and the initial release of the 100 series transceivers. The Z-Wave Certification program continues to be strengthened with new features and new tests that make every Z-Wave certified product better and completely interoperable with every other Z-Wave device on the market. Interoperability is the advantage Z-Wave has over the many other competing wireless protocols for IoT.

Newer devices have been tested more rigorously and use the latest chip sets for better RF range and mesh network routing algorithms. So given the choice it’s generally better to buy newer devices using the latest technology.

Conclusion

Choose a Z-Wave Plus device over a non-Plus device even if you have to pay a little more. A Z-Wave Plus device uses the 500 series chips with the latest RF technology and firmware and has been tested under the Z-Wave Alliance Certification program which is quite difficult to pass. Rest assured that the Z-Wave device you purchase today will continue to be interoperable with future versions of Z-Wave technology for the foreseeable future.

 

Z-Wave Saved My Fathers Life

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My father is a cantankerous curmudgeon but at 89 years old he deserves to be a little crusty. In his infinite wisdom at the age of 79 he decided to move away from his family here in New England and purchased a home in warm sunny Florida. He was happy he no longer had to freeze in the cold of winter but I was unhappy because now he was 2,000 miles away and I worried something might happen to him. If someone broke in or if he fell no one would know potentially for weeks. To ease my worries I applied my technical expertise and deployed an inexpensive Z-Wave based system to keep an eye on him.

HomeSeer to the Rescue

HomeseerZeeS2

HomeSeer sells a Raspberry Pi based Home Automation system with a built-in Z-Wave interface called the Zee S2. This small box needs only 6 Watts of power but contains a complete Linux computer that can serve web pages and runs the HomeSeer HS3 application. My initial system was just the HomesSeer Zee S2 ($199) and two Express Controls EZMultiPli Multi-sensors ($99) for a total cost of $300 for my peace of mind.  No monthly charges, no “monitoring fees” or any other costs so this is indeed a low-cost solution. All of the Z-Wave devices just plug in with no wiring, no batteries and everything pretty much plug-and-play. In less than an hour the system went from the box to fully installed and the web interface up and running via my phone or computer.

The HomeSeer system is accessible 24x7x365 via their portal at myhs.homeseer.com. No complex router tunneling or anything like that – just plug the Zee S2 Ethernet cord into HS3the router and then login to it from anywhere in the world. The system is secure and password protected. The HS3 application serves web pages with a status of every Z-Wave device. The HS3 application runs on the Raspberry Pi so all processing is local which means temporary Internet connectivity outages are no problem.

The HS3 user interface shown here is utilitarian which is fine for this application. HomeSeer has an easy to use IF-THEN “events” page which is quite powerful. The HS3 system constantly monitors the motion sensors and depending on the time of day sends me a text anytime there hasn’t been motion detected in the house for more than 5 hours. I placed a motion sensor next to his bed and another in the kitchen. Since he typically would get up several times each night, my 5 hour time limit rarely false-triggered. The trigger was extended longer during the day since he would be up and around the house and not in the bedroom for more than 8 hours at a time.

Nothing is Perfect

When I first put the system together, it seemed to work reliably. However the Zee S2 unit was installed at the far end of the house near the cable box. The kitchen motion

ezmultipli200
Express Controls EZmultiPli Motion Sensor

sensor was about 25′ away and the bedroom one was another 20′ away and had to pass thru several walls, the HVAC system and a bathroom. With only 3 nodes in the Z-Wave network I violated one of the key rules of a mesh network – always have more than two routes to every device. In this case I had exactly one route to each device so I didn’t have a mesh and the result was a number of false triggers because the bedroom motion sensor occasionally couldn’t reach all the way back to the Zee S2.

I was frustrated because I left what I thought was a working system but soon turned out to be unreliable. Now I was 2000 miles away and had to suffer with this system for nearly a year before my next visit to Florida. The solution was to add a few lamp modules and another multi-sensor so now I had 7 nodes with several routes to all nodes. Now the system was reliable and did not false trigger. I added an event that automatically turned on a lamp in the family room whenever motion was detected. My father really liked this feature as he always had light as soon as he entered and it would automatically turn off when he had left the room.

I thought things were pretty robust at this point but my next Achilles heel turned up rather quickly. Something caused the Raspberry Pi to crash. I couldn’t log into it and it was no longer sending me the daily emails telling me what time my father had gotten up in the morning. After nearly 2 months the system just suddenly started sending me the daily emails again. Apparently a power outage had in effect rebooted the HomeSeer system. On my next visit I put the entire system on a power strip that my father could reach so he could reset the system. I still want a power strip that has a watchdog timer function and if it doesn’t get some sort of “ping” every hour or so, it reboots everything downstream.

He Takes a Fall

At 2:39am one morning in mid-November 2017, my father fell in his bedroom. He was unable to get up. He was unable to call for help. My HomeSeer system sent me a text at 7:39am stating he had not gotten up. That seemed like an odd time for him to not get up so I tried to call him. After several calls with no answer and checking the HomeSeer system to see that there has been no changes since 2:39am I became concerned. I had the Sheriff stop by and check on him and it turns out he was on the floor, awake but unable to move. The EMTs were called and he was taken to the hospital. In just 5 hours he was already dehydrated and would have slowly died a painful death in a day or so if my system had not been in place. The Z-Wave system saved my fathers life.

Looking back on it now, I had noticed that his morning schedule had started to vary significantly from day to day. For years he had been getting up at a pretty predictable time of around 10am. But in the months prior to his fall, his schedule had started to vary from 8am to as late as 1pm in the afternoon. When we talked on the phone he said he was fine but clearly he was struggling. He enjoyed being warm in Florida and he was happy and I was confident that my Z-Wave system would alert me to any major problems which it did.

Z-Wave Multi-sensor Version 2.0 with SmartStart – Batteries not Required

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Merrimack, NH March 19, 2018 – Express Controls LLC announces the release of Version 2.0 of the EZMultiPli three-in-one multi-sensor and Z-Wave repeater. The Z-Wave Plus certified device is one of the first available SmartStart devices on the market and is available for purchase now on Amazon.

EZMFrontAnimFeatures

  • Motion Sensor
  • Temperature Sensor
  • Light Sensor
  • Color Indicator Night Light
  • Z-Wave® Range extender
  • Wall Powered – No Batteries, No wires
  • Screw tab for secure installation
  • SmartStart enabled

The new features for the 2.0 version are the addition of a screw tab for secure mounting and SmartStart. The tab on the enclosure enables secure mounting in either a standard outlet or a decorator outlet common with GFCI circuits used in kitchens and baths. The tab ensures children, elders, cleaners or maintenance personnel can’t easily remove the sensor. Secure mounting means the Z-Wave network is robust and reliable since EZMultiPli typically is a key repeater in the Z-Wave mesh network. Never worry about the batteries dying since EZMultiPli is wall powered. Installed by anyone with just a screwdriver – no wires, no batteries, no damage to the walls drilling holes.

SmartStart

qrPackSigma Designs SmartStart technology makes installation easy and secure. If your home automation system supports SmartStart, the first step is to scan the QR code on the back of EZMultiPli. If EZMultiPli was purchased as part of a kit containing several SmartStart devices, the QR code may have already been scanned at the factory. The next step is to simply plug EZMultiPli into a wall outlet and it will automatically join the Z-Wave network. Inclusion should begin within a couple of minutes but may take longer if several SmartStart devices are added at the same time. SmartStart uses the latest Security S2 encryption technology for all radio communication ensuring your system is secure.

Express Controls

Express Controls provides expert consulting services for the design and manufacture of wireless Internet of Things (IoT) products for Z-Wave product development teams. Express Controls has been been developing IoT products using Z-Wave protocol since 2003 and the 100 series Z-Wave RF transceivers.  Currently we are developing Z-Wave products using the latest Sigma Designs fifth generation 500 series RF modules which enable us to quickly prototype any IoT device you can imagine.  We have resources available for PCB design and layout as well as industrial design and 3D printing to help visualize the entire IoT product quickly.   Leverage our knowledge of the nuances of the Z-Wave protocol to bring your Z-Wave product to market quickly.  

Contact

Eric Ryherd – CEO and Z-Wave Expert Consultant

info@expresscontrols.com – +1 (603) 889-4841 – ExpressControls.com

CES 2018

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The Consumer Electronics Show in Las Vegas is THE trade show for smart home technology and all things cool and new and geeky. It’s a massive show and I only spent one day there and never made it out of the Sands convention center which is one of the smaller venues. If you’ve never been to CES it is something to see. The crowds are enormous and the tech is brand new. So new, some of it will never actually make it to market as there is plenty of smoke and mirrors.

Eric Ryherd wireless IoT consultant expert

My purpose is obviously to seek out the latest news about Z-Wave and chat with my clients. The Z-Wave Alliance invited me to man the “Ask the Expert” desk at the show for a few hours which I was happy to do. My expert knowledge of Z-Wave answered simple questions like “what’s Z-Wave?” (It’s like wifi but low power) to complex questions about the rules around Security S2 and SmartStart.

The most common question is always what’s the difference between Z-Wave and Zigbee? My short answer is that Zigbee is like silos. If you can develop an app, gateway and all the devices you need, then Zigbee will work OK. Z-Wave however was a mesh network from day one and every Z-Wave device can talk to every other Z-Wave device regardless of the manufacturer. Z-Wave is built around standardized command classes so every hub knows precisely what format a temperature sensor is sending the data. Is it in celcius or Fahrenheit? Tenths of a degree or hundredths? With Z-Wave, the format is fully specified. The other protocols let you decide the format which is fine if you have the huge budget to do it all. But if your investors have you on a shoestring budget then Z-Wave is the way to go. I have much longer answers to the Z-Wave vs. Zigbee question but much too long to keep your interest in a quick blog post.

The big announcement for Sigma (other than the acquisition by Silicon Labs) is the announcement of the 700 series. Unfortunately details remain shrouded in secrecy but Sigma has put a stake in the ground of having developers kits by summer 2018. Finally having a real 32 bit ARM processor will be a huge productivity improvement for us IoT developers.

I had limited time to walk the floor but it does seem that smart home has finally taken off. There are so many companies making cool gizmos it’s overwhelming. From sun tracking solar powered umbrellas to cameras of every size and resolution to lots of new hubs there is no way one person can take it all in. You’ll just have to see for yourself.

The Z-Wave Alliance booth is even bigger this year filled with companies hawking the latest IoT thingamagiggy using Z-Wave. Every one of them able to talk to all the other Z-Wave doodads. The booth was busy all day long. I did wander past the tiny Zigbee booth buried in the back of the hotel with a few people in it but nothing like Z-Wave.

SiLabs acquires Z-Wave – Good or Bad?

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On Friday of last week Silicon Labs signed an agreement to purchase Sigma Designs for $282M.

The question is: is this good for Z-Wave or bad? 

logoSilicon Labs is a well respected semiconductor manufacturer with an array of microcontroller products  from 8-bit 8051s thru modern low-power ARM CPUs. Silicon Labs has been chasing the IoT market since before IoT was a “thing”. Their low power micros have industry leading features often integrating the latest connectivity solutions like USB, Zigbee and now Z-Wave.  With a market cap of nearly $4B, Silicon Labs (SLAB) has a lot more financial muscle than Sigmas (SIGM) mere $265M could provide. All Z-Wave licensees should rejoice that a much larger company is now  supporting Z-Wave with the accompanying increase (we hope) of resources.

sigma-logoIn my opinion, the most interesting part of the announcement is that SiLabs is buying Z-Wave and not Sigmas primary business of Set-Top-Box processors. The announcement states: “Sigma Designs is in active discussions with prospective buyers to divest its Media Connectivity business”.  The announcement goes on to say that if Sigma can’t unload its “Media Connectivity business” then SiLabs will buy just the Z-Wave portfolio for $240M thus making the rest of Sigma worth only $42M assuming someone is willing to pay that much for it.

The Past

logo_zensyszwaveZ-Wave was originally invented by Zensys based in Copenhagen Denmark in 1999. Originally the Z-Wave protocol used Chipcon radios (acquired by TI) and Atmel processors (acquired by Microchip). In 2003 Zensys announced its own custom designed “100 series” Z-Wave transceiver which was a complete Z-Wave capable IoT System-On-Chip. In 2008 Zensys was struggling financially.  Fortunately Sigma stepped in an purchased Zensys for an “undisclosed amount”. Nine years later, Sigma has sold Z-Wave for a very nice ROI of perhaps 100X. Mergers and acquisitions in the semiconductor industry are frequent as technology and markets shift in unforeseen ways.

The Present

Z-Wave is growing like crazy as the number of 100% inter-operable mesh networked Z-Wave devices on the market continues to increase. There are now over 600 Z-Wave licensees with over 2100 products already on the market. With the recent addition of the AES-128 encrypted Security S2 communication and SmartStart to simplify the building of the Z-Wave network, Z-Wave shows it is continuing to evolve while still being completely backwards compatible with all the existing devices all the way back to the 100 series.

The Future

The future is nearly impossible to predict. I certainly don’t claim to have a clearer crystal ball than the next guy. But this acquisition bodes well for the future of Z-Wave. The additional resources should accelerate the introduction of the ARM Z-Wave microcontrollers which in turn will bring more Z-Wave products to market faster and cheaper. The soon to be announced next generation transceivers are expected to utilize modern ARM processors and make a significant leap forward in debug capabilities that are not present in the current 8051 8-bit CPUs. Z-Wave developers will finally be able to single step through their code instead of relying on printf to output a few cryptic characters giving you meager clues where your code has gone wonky.

Conclusion

The acquisition of the Z-Wave portfolio by a financially strong IoT silicon manufacturer is a “good thing” for the future of Z-Wave.

Eric Ryherd Presenting “IoT Device Testing Best Practices” at Z-Wave Summit in Oklahoma City September 26-28, 2017

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Z-Wave Developers and Marketers will come together at the Z-Wave Summit at the Jasco facility in Oklahoma City September 26-28, 2017. You have to be a member of the Z-Wave Alliance to attend. I highly recommend attending if you are developing Z-Wave devices . Networking with other Z-Wave developers and having intimate access to the Sigma Design and Alliance engineers and marketing folks is invaluable. To attend, register via the Alliance member-only web site. The Alliance always has some fun in the evenings too so it’s not all work!

Eric Ryherd Presenting

Express Controls founder and Z-Wave expert Eric Ryherd (aka DrZWave) will be presenting at the summit for the 4th consecutive year. Last years presentation was “Seven Things you probably don’t know about Z-Wave” and was well received. I was surprised how many engineers were completely unaware of the many new features and command classes that have been added to Z-Wave in the past couple of years. This year’s topic is “IoT Device Testing Best Practices“. I’ll go over some of the failures I’ve found over the last several years in both my products and other products I’ve tested.

Abstract

Z-Wave wireless Internet of Things (IoT) devices are hard to test! There are countless devices already in customers hands with bugs in them that make Z-Wave seem unreliable when in fact many of the issues are bugs in the device firmware.  Eric Ryherd, Z-Wave expert and consultant, describes some of the  failures that are still shipping today and best practices when testing your IoT device to reduce the chance your device fails in your customers hands. Simple command sequences sent one at a time by a test engineer is not representative of the real world packet storms that occur in an apartment building with complex RF reflections and multiple interfering RF networks. Your device has to work in the real world and to do that you need to simulate those terrible conditions that do not happen on the engineers desk.

Author Bio

Eric Ryherd licensed Z-Wave in 2003 to develop IoT devices before the term IoT even existed. Light switches, motion & temperature sensors, water valves and meters, hubs, window shades, remote controls are just a sample of the Z-Wave IoT devices developed and tested by Express Controls. Eric applies his Z-Wave expertise in consulting, training and assisting with Z-Wave Certification to companies of all sizes. Read more by Eric at his blog – DrZWave.blog.

Z-Wave Challenges in MDUs and How to Resolve Them

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Deploying a robust Z-Wave network in MDUs (like apartment buildings or hotels) can be challenging unless you follow a few basic rules.
The most common problem in MDU deployment is that many installers fail to take advantage of Z-Wave’s number one technical advantage – the mesh network. Every always-on (wall powered) Z-Wave device adds a node to the mesh. But battery powered devices like door locks, sensors and many thermostats do NOT add nodes to the mesh – they merely benefit from other devices on the mesh network. A system where there is one Z-Wave hub and a door lock in each dwelling unit will result in a poorly performing system because there is no mesh! To build a reliable mesh, every device in the network needs at least two routes between the hub and every device on the network. This means you need at least one Z-Wave repeater or lamp module in every network.
An MDU can easily have dozens or even hundreds of units all within Z-Wave range of each other. If each unit has just a single Z-Wave hub and a door lock, then each unit causes interference with every other unit resulting in a cacophony of Z-Wave traffic. A better solution is to have one hub serve 5 or even 10 units with each unit having at least one always-on device within it to provide a good “mesh” node to access the battery powered devices. Always-on devices in adjacent units help provide routing pathways to improve the robustness of the network. The installer needs the proper tools to evaluate the best location for these always-on devices to ensure a high-quality mesh network with plenty of alternate routes.
Another challenge in MDUs is that things are always changing. An owner might install a mirror (which is a metal plate on glass) or a metal appliance that significantly alters the Z-Wave quality within the unit. Even though the mirror or appliance is not in between the hub and the door lock does not mean that it won’t cause connectivity problems. The solution to this issue lies again with the mesh network and having alternate routes. Since things are always changing, the hub needs to have a policy to “heal” the network occasionally to adjust to the changes in the environment.
If some door locks seem to have short battery life then you might be suffering from limitations in older, pre-500 series Z-Wave devices. Early generations of Z-Wave would wake up battery powered devices like door locks using only their NodeID to request which node to wake up. This works fine in single family homes since every node on the network has a different NodeID, but in an MDU with multiple adjacent Z-Wave networks, if the door lock in each unit is NodeID=2, then every hub will wake up every door lock in the building any time a unit needs to check on the battery level of any door lock. The solution is to ensure each adjacent installation has a different NodeID for door locks or battery powered nodes. Thus, apartment 101 will have the door lock as NodeID=02, apartment 102 will have the door lock as NodeID=03, and so on. The latest generation of Z-Wave solves this problem so as these newer locks come on the market this issue will disappear.

A few quick rules for deploying Z-Wave in MDUs:

  1. Always build a Z-Wave mesh
  2. Install fewer hubs
  3. Use tools like IMA to validate mesh networks
  4. Don’t build the same network in every unit
  5. Network must be flexible due to changing environments

Seven Habits of Highly Effective Z-Wave Networks for Consumers

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You have a Smart Home using Z-Wave as a wireless technology for all these Internet of Things (IoT) devices to communicate with each other. But maybe things are not working quite as well as you expect. You press a button on your phone and 1… 2… 3… and then finally a light comes on or maybe it doesn’t come on at all! Another common problem is when a battery powered sensor was updating the temperature last week and this week it just doesn’t seem to be sending updates anymore or at best sporadically. As a Z-Wave expert I’ve built and rebuilt hundreds of Z-Wave networks and have come up with a few habits to make Z-Wave networks more reliable.

1. Minimize Polling

This is probably THE number one mistake new users of Z-Wave make. They figure Z-Wave is a high speed network so they can just poll a light switch every 3 seconds and then react to any change in the switch. Z-Wave and most other wireless networks work best when the network is highly available. If the network is busy, every device that needs to send a message has to wait its turn and then compete (and often collide) with all that polling traffic. Collisions slow everything down just like rubber-necking on the highway.

Polling used to be the only way to get around a patent that fortunately expired in February 2016. The patent forced many light switch manufacturers to not send a message when you flipped the switch. Several manufacturers found ways to get around this or they licensed the patent. But now that the patent has expired, you can get light switches that do send a report immediately when their state has changed.

So the primary way to minimize polling is to replace the few devices in your Smart Home that trigger an event  (or SmartApp or Magic or whatever your hub calls it) with one that will instantly send an update. If you have some older switches but they’re not that important to instantly know their state has changed, you can still poll them but no more than once every few minutes. Remember that if you have 60 Z-Wave devices and you poll each one once/min then you are polling once/second and the network is hammered! So only poll a couple of nodes!

2. Have enough devices to create a mesh

I can’t tell you how many people I’ve worked with that had a door lock and a hub and nothing else, maybe a battery powered thermostat. And they wondered why the connection to the lock was unreliable when the hub was at the far end of the building! Z-Wave relies on Always-On (110VAC powered) nodes to build a “mesh” network. The mesh is the key to Z-Wave reliability. Every Always-On node acts as a repeater in the mesh and is able to forward a message from one node to another in the mesh. But only the Always-On nodes can forward a message. Battery powered devices like door locks and battery powered thermostats cannot forward messages. Only the Always-On nodes can.

Solution: If some devices are not reliable, add more Always-On devices. Add a Z-Wave repeater or any device like a lamp dimmer. Even if you don’t use the lamp dimmer it will act as a repeater and improve the network. I have a few lamp switches I use for my Christmas lights which I leave plugged in year round because they help the Z-Wave network since these nodes are at the periphery of my home.

Distance between nodes is not always the criteria for adding more nodes in a network. The Z-Wave radio signals may bounce off metal objects like mirrors or appliances and cause two nodes that are only a few feet apart be completely unable to talk to each other due to reflections of the radio signals. Adding more nodes in the mesh provide alternate routes to nodes that otherwise might be in a dead zone due to these reflections cancelling out the radio signals.

3. Place the hub in a central location

Putting the hub in a corner of the basement might be convenient, but its a terrible idea for Z-Wave. The hub is the most important node in the network and should have the best location possible. While Z-Wave is a mesh network and can route or hop thru other nodes in the mesh, each hop is a significant delay and chokes up the network with more traffic. Ideally the hub should reach 90% of the nodes in your Smart Home without relying on routing. If the hub has Wifi then putting it in a central location is easy, you just need a wall outlet to plug it in. I have my hub hung off the back of a TV cabinet in roughly the middle of the first floor of my home.

4. Heal the Network

Once a Z-Wave network is built, it has to be “healed” so every node can use all the other nodes in the network to route messages. This healing process can take many minutes to even hours depending on the size of the network. When you first build a Z-Wave network, the first node added only knows that the hub is in the network. When you add a second node, the hub knows that both the nodes are in the network but the first node you added has no idea that node 2 is there – unless you heal the network. So any time you add a node, you need to heal at least a few nodes in the network if not the entire network. Be cautious with the healing process – it uses 100% of the Z-Wave bandwidth during the process and every node will wake up every FliR node (door locks) at least once which will drain the batteries of the FLiR node. Generally only heal when nodes have been added or removed or if there seems to be a problem in the network.

Z-Wave is able to self-heal automatically. Z-Wave nodes will try various routes to get their message thru if at first it doesn’t succeed.  The node will remember the Last Working Route and try that one first for the next message. But if the nodes have no idea there are other nodes in the network they have no way of knowing what routes to try so at least one full heal of the network is required.

HomeSeer

homeseerhealHomeSeer has several platforms so the precise method might be slightly different than shown here. From the web interface home page select the menu Plug-Ins->Z-Wave->Controller Management then select the Action “Fully Optimize a Network”. The network wide heal will take some time depending on the size of the network.

SmartThings

SmartThings Expert Z-Wave Eric Ryherd DrZwaveSmartThings  user interface is thru their app which makes finding the network heal a bit of a challenge. Start from the dashboard and click on the three lines in the upper left corner. Your Hub should be the first choice in the menu that slides out, click on your hub. A new menu comes up, click on the last choice “Z-Wave Utilities”. The last choice on the next menu that slides in is “Repair Z-Wave Network” so click on it and then click on “Start Z-Wave Network Repair”. The repair will take from minutes to over an hour depending on the size of your network.

Vera

verahealVera has several versions of their UI but each of them has a similar menu structure so these instructions should work on any version. The Vera version shown here is UI7. Use a PC to log into GetVera.com and select your hub. From the Dashboard, select Settings->Z-Wave Settings and then click on the advanced tab. At the bottom of the advanced tab is the GO button to run the “Update Node Neighbors”. Depending on the size of the Z-Wave network this process will take several minutes to over an hour.

5. If a device doesn’t pair, first exclude it, then include it

You’ve taken the brand new Z-Wave IoT widget out of the box and you’ve tried to pair it (the Z-Wave term is “inclusion”) but it just won’t include! Arrrghhh! The first thing to try is to exclude the node first and then try including it. Any hub can “reset” or exclude a Z-Wave device even if that device was previously connected to another network. Some manufacturers occasionally fail to exclude the device during testing so the device may already be connected to their test network. Z-Wave Expert IoT WirelessOr you may have inadvertently included the device but the inclusion process failed somehow and the hub is confused. Excluding the node should reset it to the factory fresh state. Newer Z-Wave Plus devices (which have this logo on them) are required to have a way to reset them to factory defaults using just the device itself. Every device is different so you’ll have to refer to the device manual to perform a factory reset but if all else fails this should make the device ready to pair. Naturally having the hub physically close to the device being paired will also help though most devices can be paired from a distance.

Secure devices like door locks are particularly challenging to pair. First the secure device has to join the Z-Wave network, then the AES-128 encryption keys have to be exchanged and if that process fails (which it does on occasion), then you have to exclude and try the inclusion process all over again. Secure devices definitely want to be within a few feet of the hub during inclusion to ensure reliable and speedy Z-Wave communication.

6. Battery life and how to maximize it

When a battery powered Z-Wave device wakes up and turns on its radio, it uses 10,000 times more battery power than when it’s asleep. So the entire trick to making batteries last is to minimize the amount of time the device is awake. Some devices naturally have other battery draining activities mostly involving motors to throw a deadbolt or raise a window shade. Obviously any motor will use a lot more battery power than the Z-Wave radio but the radio will play a significant role in battery life.

When a battery powered device is added to a Z-Wave network the hub should do two things:

  1. Assign the Association Group 1 NodeID to the hub
    1. Association Group 1 is the “LifeLine” in Z-Wave and devices use this lifeline to send all sensor data and alerts to this node
    2. All hubs are required to assign Group 1 but double check this assignment
  2. Set the Wake Up Interval to no more than once per hour and ideally only a few times per day
    1. Every hub assigns the WakeUpInterval differently and largely handles it behind the scenes so this may be difficult to verify or change
    2. If the device is waking up every few minutes and sends a sensor reading then its battery life isn’t going to be more than a few weeks
    3. The battery level of the device is usually reported at the WakeUpInterval  rate

Many sensors have other Association Groups or Configuration Parameters that will let you specify the frequency of sensor readings. Realize that the more often the sensors report in, the shorter the battery life.

7.  Dead nodes in your controller

One of the big problems in Z-Wave network maintenance is eliminating “dead” nodes. When a device fails or for whatever reason is no longer in use, then it needs to be removed from the controller. If it remains in the controller then the controller will try to route thru this dead node on occasion resulting in delays in delivering messages. Eventually the self-healing aspects of Z-Wave will make this less likely but various devices will on occasion attempt to route thru it. Since the node is dead, that wastes valuable Z-Wave bandwidth and potentially battery power of sleeping devices. Occasionally running a Heal on the network will remove the node from the routing tables but it will remain in the controllers routing tables. It is best to completely remove this dead node. Each hub has a different method for removing dead nodes and usually requires going into an advanced Z-Wave menu.

Following these guidelines will help your Z-Wave experience be more robust. If you have more questions please feel feel to reach out via email to drzwave at expresscontrols.com.