Unable to get DateTime to work

[Tinimini (Tuomo Syvänperä)]

I have the following item defined:
DateTime DebugTest “Last Heartbeat [%1$tH:%1$tM]” { mqtt="<[mosquitto:debug/test:state:default]" }

And in my sitemap I have:
Default item=DebugTest

But no timestamp is shown. Only ‘Last Heartbeat -:-’. And yes, I have published something in that debug/test mqtt queue

[sihui]

I would try

Text item=DebugTest

but that is just a wild guess

[Marty56 (Martin)]

Is your mqtt broker able to send a DateTime item?
Probably not.
Better use a String Item to receive the data from your mqtt broker and then write a rule which logs the time when you received this data.

[Tinimini (Tuomo Syvänperä)]

Ah. For some reason I thought that it’s going to give me the timestamp when the message was received.

[Tinimini (Tuomo Syvänperä)]

Is it possible to make a rule that would notice if the time between two heartbeats has been too long?

[rlkoshak (Rich Koshak)]

@Tinimini

Is it possible to make a rule that would notice if the time between two heartbeats has been too long?

[Deprecated] Design Patterns: Generic Is Alive

There is now a Rule Template on the marketplace to implement this for you. See below for instructions on how to set it up. Please see Design Pattern: What is a Design Pattern and How Do I Use Them for a description of what Design Patterns are and how to use them. Problem Statement Many sensors report status to openHAB periodically (e.g. temperature sensor) or unpredictably (e.g. motion sensors) and a subset of these sensors do not have a built in way for openHAB to query whether or not they a…

I particularly recommend the Expire Binding version near the bottom of the first post.

Also, I think you could receive an MQTT message into a DateTime Item as long as the value of the message is epoc (it must be a number, not a String representation of the number) or in ISO 8601 format.

[Tinimini (Tuomo Syvänperä)]

Thanks, I will take a look at the thread you mentioned.

I don’t have a timestamp in my MQTT message. It’s just a generic message that let’s you know that the sensor is still alive, the actual content of the message is irrelevant (it’s a running number I believe), so I just wanted to get the timestamp when the message was received. And if I don’t get a heartbeat by some predetermined time, I would like to fire off an alarm letting me know that the sensor is offline (a poor man’s battery monitor, if you will).

[Tinimini (Tuomo Syvänperä)]

I was kinda hoping I could do something like this:

DateTime DebugTest "Last Heartbeat [%1$tH:%1$tM]" <clock> { mqtt="<[mosquitto:debug/test:state:EXEC(/bin/date +%s)]" }

To get the timestamp of the mqtt event.

[Tinimini (Tuomo Syvänperä)]

Okay, I basically got it working the way I wanted for now. Using the following rule:

import org.openhab.model.script.actions.Timer

var Timer timer

rule "Sensor Heartbeat"
when
  Item Node102_Heartbeat changed
then
  logInfo("heartbeat", "Heartbeat from node: " + Node102_Heartbeat)

  if (timer != null) {
    timer.cancel
    timer = null
  }

  timer = createTimer(now.plusSeconds(5)) [|
    logWarn("heartbeat", "No Heartbeat from node: " + Node102_Heartbeat")
  ]
end

Now I just need to modify my items so that they belong to the same group and this rule monitors the whole group. I suppose it’s possible to access the specific item in that group? Or is it not possible to make a rule that would react to a change to any item within a group?

[Tinimini (Tuomo Syvänperä)]

Actually now that I started reading that thread about the generic is alive pattern, that might be the way to go. I’ll see what I come up with after reading it through

[rlkoshak (Rich Koshak)]

@Tinimini

I was kinda hoping I could do something like this:

That might work and it is an approach I never considered. I’ve never used the Exec transform before.

What didn’t work for you? Have you installed the exec transform? It might require the exec1 binding to work. Check the logs for errors.

I think most of us create a rule to update a DateTime when the associated Item gets an update but I’m intrigued by the idea of doing the same in a transform. Of course for it to work date needs to output in the correct format that can be parsed by the DateTimeItem.

@Tinimini

Okay, I basically got it working the way I wanted for now. Using the following rule:

I don’t know the nature of your messages but you might want to use received update as the trigger so the rule runs even when an mqtt message comes in that doesn’t result in a state change.

@Tinimini

suppose it’s possible to access the specific item in that group? Or

See:

Design Pattern: Working with Groups in Rules

Edit: Updates for OH 4, inclusion of JS Scripting and Blockly examples, removed the doors example as it’s superfluous. Please see Design Pattern: What is a Design Pattern and How Do I Use Them for how to read and use DPs. Problem Statement One powerful way to consolidate code in rules is to use array/list manipulation operations on the members of a Group. For example, filter down to just those members that are ON, get a list of the labels of those Items that are NULL, etc. Concept [image] T…

Design Pattern: Associated Items

Please see Design Pattern: What is a Design Pattern and How Do I Use Them for how to read and use DPs. Problem Statement Often one will have a number of separate Items which are all related to each other in some way. For example, one might have a Contact on a door and a DateTime to represent when the last time the door was opened. This is easy enough to keep track of if there are only one or two such Items, but if one has a lot of similar Items or is using a lot of generically coded rules where…

@Tinimini

Or is it not possible to make a rule that would react to a change to any item within a group?

Not quite. You can trigger a rule based on updates to a group but the rule will trigger multiple times per Item update. Or you can trigger a rule with each item listed as a separate trigger and use the trick in the working with groups link above to identify which Item triggered the rule.

[Tinimini (Tuomo Syvänperä)]

@rlkoshak

What didn’t work for you? Have you installed the exec transform? It might require the exec1 binding to work. Check the logs for errors.

I’m not quite sure. It seems that if I use anything other than ‘default’ as the transform for MQTT items, they never get executed. There was no log entry in event log when I published something in the topic if I used some transformations. It only seems to work when using default.

But it looks like the rule based approach might work better anyway as I need to react to the heartbeat as well, so might as well do it in the rules.

It seems that I have an awful lot of reading to do. I will get right to it. I’ll post here when (if?) I get this thing working.

Big thanks to Rich for all your help!

[rlkoshak (Rich Koshak)]

One thing to be aware of is depending on which package you choose at the start you may need to install the transforms like any other add-on. I use transforms with mqtt routinely so know they do work.