Z-Wave

Has anyone tried doing anything with Z-Wave on RISC OS (on a Pi).

There are Z-Wave USB sticks around, which I believe appear as CDC-ACM device, or at least that’s what the “linux” section of the docs suggest. I am wondering about using it as the basis for a home heating control system. How far I get with that idea is, of course, a different question :)

I thought I’d give the devices a once over and went to the z-wave web site.

Usual mix of IoT connectivity from the sale/promotional pages so lets have a look at their technical info.
Right, so clicking on the developer link to take you to the log in / register page gives you a certificate message:

“Your connection is not secure

The owner of z-wave.sigmadesigns.com has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website.

and the reason is:

z-wave.sigmadesigns.com uses an invalid security certificate. The certificate is only valid for z-ware.silabs.com. Error code: SSL_ERROR_BAD_CERT_DOMAIN

They expect you to log in to what could be a spoofed / hacked site? Thanks but, no thanks.
Then they expect you to believe their product is halfway secure?

There are probably numerous other suppliers that can do things properly.

On the specific issue of heating control Dave Higton has a working setup designed round/with a Raspberry Pi so I’d recommend speaking to him for details. You could then look at extending the design.

Certainly far easier than trying to get meaningful info from a setup that can’t even secure their website properly.

My son gave me a Z-Wave USB stick a while ago. I haven’t done anything with it yet. Z-Wave devices look fairly expensive to me, bearing in mind that I don’t have a use case for even one, so I’d have to buy one just for the joy of “Light goes on, light goes off”, which wouldn’t keep me interested for many minutes after it had first happened.

I’d have to buy one just for the joy of “Light goes on, light goes off”

Well, assuming that it works like Philips’ Hue, you can also make the lights fade :)

I’ve actually written a controller app for my Hues, although at the moment it’s probably not much use to anyone else.

Wow.

Okay, let’s put it like this. If a company wants me to put anything like that in control of something “mission critical” (heating, access control, etc) then there are three simple requirements:

• Accept liability for hardware and intrinsic security failures and don’t try to disclaim it away as not their responsibility

And:

• Supply full complete source code (such that a fresh firmware can be built and installed) in order that it can be examined and audited (NDA acceptable)

Obviously I don’t expect to hold the company liable for modified firmware, but I do expect them to accept liability for failures of the supplied firmware.

And:

• Demonstrate that the device will continue to function when internet connectivity fails and, if applicable, that it will not become an impediment in the case of a power failure (nor that it will fail unsafe).

To explain that last point, I would not expect a heating controller to work when there’s no power as the rest of the system won’t be operative. However I also would not expect to be locked out of my home because the smart lock isn’t working nor would I expect it to deactivate in an unlocked state – there should be a traditional key override to open the lock.

Accordingly, I expect to continue opening the door with a metal key and mechanical lock for a while yet. Sometimes low-tech is just so much less hassle.

Z-Wave has nothing inherently to do with the Internet. It’s all local.

It’s all local.

It would be magic if they can keep the wireless signals so local they cannot be interfered with! I see you can control and even upgrade the firmware of connected devices. And the wireless net is connected to your PC? Is the PC air-gapped from the internet?

When I say it’s all local, I mean that a Z-Wave network doesn’t require connection to the Internet to work. As distinct from numerous proprietary wireless control systems, which do require Internet connection because they go out to someone’s server somewhere and back in, in order to work at all. I’ve always avoided those.

If you want to control or interrogate Z-Wave devices from outside your local area, or upgrade their firmware, then of course you’re going to need Internet connection. But the Z-Wave network’s normal operation is still all local.

As distinct from numerous proprietary wireless control systems, which do require Internet connection because they go out to someone’s server somewhere and back in, in order to work at all. I’ve always avoided those.

I was thinking about those supposedly smart Nest gizmos that all failed when the mothership went down. https://www.theregister.co.uk/2018/05/17/nest_outage/

But the Z-Wave network’s normal operation is still all local.

Have you put your Z-Wave to the test and denied them internet access? :-)

I don’t think they devices themselves have any sort of access other than other nodes on the mesh network itself. Of course one of those nodes can itself have internet access, but AIUI the network they’re on is local.