Sensor Area Networks (SANs)

[davidbrady]

(06-09-2013 03:26)nedb Wrote:  Still, I'm getting a kick out of your pool monitor. Imagine monitoring your pool temperature from the banks of Puget Sound~it does suggest possibilities.

Hey Ned,

It is a kick; I have to agree! A thermometer's not a very interesting device but a networked thermometer is endlessly fascinating. :-) What's even cooler is fastening my swimming pool to the back of a semi, towing it across country, and monitoring the water temperature the entire way, and from anywhere! That's what we're doing here.

What I find reassuring is the reliability of the SAN, (at least so far). I've had my XBee's running for well over a month in a simple coordinator and router mesh network; i.e., a 2 node network. (Every ZigBee mesh needs one XBee acting as a coordinator; the remaining XBee's in the mesh are routers, but there is the concept of an edge XBee). I've left my simple network untouched for weeks, then I come along and make a keystroke and suddenly the mesh is alive and communicating. It's always up! Very impressive reliability so far, and I'm finding the same quality of up-time with my XIG gateway and Cloud connectivity. (at least so far).

Any existing MiFi account will work, you just need to add another device to the plan and activate it on your XIG. If you have a family plan this might be economical. For those who'd rather buy as they go the sliced up M2M accounts (http://www.embeddedworks.net) may be the most affordable.

I'm fairly certain that the Internet enabled home thermostats at Lowes require a statically assigned global IP address to be accessible over the web - they're really meant for home networks where locally assigned (NAT) IP address aren't a problem. I believe this is the challenge of a mobile SAN - morphing local IP addresses into a global address as the devices move across the country and providing an abstract name server scheme that allows WaGu to resolve down to the target XBee regardless of the user account we're working with and the location of the Wanderlodge. (this is the magic of the Cloud :-)

Of course, one doesn't need to use the Cloud; it's not required. The XIG can talk directly to any website. For WaGu the Cloud helps with scalability. I'd like WaGu to have a set of general purpose PHP scripts that do basic functions. I'd like WaGu to index into the PHP using an account identifier and I'd like it to pull deviceID's out of the Cloud using the same account identifier. Most of what I'm trying to do is related to giving WaGu the facilities necessary to provide monitoring and control for anyone who wants it; hence, my reliance on the convenience and scalability of the Cloud.

As you discovered the Digi Device Cloud does offer free Developer accounts for up to 5 devices. This is clearly the way to go. Anyone who wants to implement a SAN in their 'lodge would register for a free Developer account. The way I understand it you're limited to 5 devices, but a device is defined to be a XIG gateway. You can hang as many XBee's off your mesh as you'd like and they can all report, but Digi counts the whole shebang as one Device identified by the XIG.

Here's some properties that I pulled off the Cloud to help identify some of the numbers in the XML form:

product: XIG PC Gateway
company: Digi International
MAC Address: 07:2B:2A:16:1F:00
deviceid: 00000000-00000000-001F16FF-FF2A2B07
XBee extended address (coordinator): 00:13:a2:00:40:a0:3d:2f
XBee extended address (router): 00:13:a2:00:40:a0:3d:3f
primary interface IP Address: 10.119.77.174
global Address: 208.81.155.21 (I altered this to protect the innocent :-))

So in the XML response form we have:

The identifier for the Gateway (XIG) device:
devConnectwareId: 00000000-00000000-001F16FF-FF2A2B07

The identifer for the XBee coordinator hanging off the Gateway (XIG):
xpExtAddr: 00:13:A2:00:40:A0:3D:2F

The identifier for the XBee router (this is the XBee that's piggybacked onto my temperature sensing Arduino):
ddInstanceName: XBee_40A03DF3

Not sure what this identifier represents, possibly my loginId:
cstId: 4736


This page will point you to Windows/Linux/Apple XIG downloads.