Have OpenHAB Report an Offline RFM69 Gateway

[papa]

        Have OpenHAB Report an Offline RFM69 Gateway,

             Step 1, Report Possibly Offline Nodes

       Updated April 21, 2020:  OpenHAB 2.5.x & Using Uptime

At one point, one of my RFM69 Gateways (I have 2 so far) was offline & not monitoring moisture in my garden. How might I have the system let me know that the Gateway might be offline?

In this thread, I reported how OpenHAB's Expire Binding could be used to flag possibly offline nodes.  At that point, when nodes' RSSI signals did not change for more than 3 minutes, I had those items report themselves "Offline?" via the Expire binding. Expire binding should be used with a value that normally changes during the time Expire binding allots. Update: The following reflects how, instead of RSSI, I now use Expire with Node Uptime. Always changing once a minute, Uptime is more reliable.

Update: Using Uptime required a small change in the node's firmware programming. Find here the Latest Choose Nodes sketch. As of April 17, 2020, that version reports node uptime to openHAB, but did not before that date. So download & customize the latest version to features the node needs.  (Fairly late in the sketch at "// send0 = true; // send uptime" I deleted the initial "//" so node Uptime is sent to openHAB.)

        Go to PaperUI/Add-ons/Bindings & install Expire Binding. (This will help us know if a device is offline.)

If you don't see the Expire Binding to install it:  When we first installed openHAB, it asked what package we wanted: Simple or Standard or Expert. We need to be in either Standard or Expert to see the 1.x bindings.  To fix this I believe you can edit \conf\services\addons.cfg.  Find the line that includes "#package = "  & change it to "package = standard" or "package = expert" (no "#" to begin & disable the setting). Save the edited file & perhaps restart openHAB.

    The following is based on my garden node. Adapt to your node:

          From my .items file (Updated)

String Node12UpTime "Gardn_12_Up [%s mins]" <network> (Nodes) { channel="mqtt:embedded-mqtt-broker:topic:mything:Node12Channel00", expire="3m,Offline?" }

    [Caution: Do not omit the comma (,) before "expire." If you omit the comma, that won't throw an error, but stale values will not be reported.]

  From the first part of this post, adapt creating a Thing for your node.

        From this post, adapt creating a Channel00 (Uptime) for your node.

            Go to your equivalent of PaperUI/Configuration/Things/Node12garden.

Click on the blue disc beside your Uptime channel. Link it to your UpTime item.        

    No additions needed for the .rules file so far.
   
    To a .sitemap file, add the equivalent for your node:

Text item=Node12UpTime

So far, the openHAB UserInterface/sitemap should report when the node is offline. (To test, you can remove the node from power.)

[papa]

        Have OpenHAB Report an Offline Gateway,

            Step 2, Add more to Step 1 Above

                Updated, April 21, 2020

I reasoned that if three of the Gateway's nodes (two nodes from one electrical circuit & one from another circuit) were reported Offline?, I could get an email message that the Gateway may be offline. Modeled after the previous post, for two more nodes on the same Gateway, take care of firmware, Things, Channels, items, sitemap entries. In the rule below, replace the two Node??UpTime with the names of your two other items.

        Then adapting to your nodes, add this to a .rules file:

rule "Is Gateway Offline" // checked every 10 minutes
    when
        Time cron "0 0/10 * * * ?"
    then
        if(Node??UpTime.state == "Offline?" && Node12UpTime.state == "Offline?" && (Node??UpTime.state == "Offline?")
            {
                sendMail("[e-mail]","from openhab","Gateway may be offline.")
            }
end

If the Gateway is ONline & any or all the above nodes are stale for longer than their Expire binding allots, the nodes' Uptime values will be reported "Offline?" on the User Interface. However, if Gateway One is OFFline, that will put all of its nodes' Uptime values into "Offline?". Then via the rule above that uses ANDs (&&), OpenHAB will see three of the Gateway's nodes' Uptime statuses are Offline? & will send a message that the Gateway may be offline.

The above seems to work. You can test it by disconnecting your gateway from power or from your local network.

Another caution: if the .items file is changed & saved, openHAB values (including the Uptime values above) revert to persisted values. Then as long as the Gateway is offline those persisted values do not change, BUT openHAB does NOT mark them as stale. The solution: if you change/re-save .items while you are testing an offline gateway, reconnect the gateway to power / network long enough for it to connect to MQTT for at least a minute & communicate some messages. Then if you want to retest an offline gateway, you can disconnect it from power or your network.