Temperature control - How do I do this?

Setup, Configuration and Use Items & Sitemaps
1

Hi,

I have a MySensors node that controls activities at my Pond (using MQTT). Whilst the norm is for OpenHAB (OH) to do the control, in this case I want the PondController (PdC) to do the work and decision making, but I want to configure it from OpenHAB (I guess you would call this centralised management, but decentralised control).

I have various ON/OFF values that I am already setting from OH and OH is also receiving the changes when I change them at the PdC. This works very well.
Additionally, I am receiving in OH the setting of the other numeric values. What I can’t figure out, is how to set the numeric values in OH and have these sent to my PdC.

The Configuration information are:

  • Temperatures (e.g. PondFreezeLimit, PondFreezeHysterisis)
  • Times (e.g. PumpOnTime, PumpOffTime)

Can anyone point me n the right direction?

Thank you

2

Hi Colin,

I think you want to have the openHAB MQTT binding publish messages to your MQTT broker, using items. For example, define an item:

Number PondFreezeLimit "PondFreezeLimit [%.1f °F]" { mqtt=">[broker:/topic:command:*:default]" }

When this Number item’s state is updated, it will publish the value to the broker on the topic. This can be done from a rule with

PondFreezeLimit.postUpdate(2)

and/or from the UI by defining a Setpoint widget in your sitemap, like:

Setpoint item=PondFreezeLimit min=-1 max=5 step=0.5
3

Hi,
Thank you so much for responding but I am still struggling a little or maybe a lot. I have to confess OpenHAB is new to me and so learning about items, sitemaps and rules. I apologise if I am missing the obvious.

I originally had the following binding in my items file. OH updates as I change configuration settings at my node and so I assume this is correct.
Number Pond_Freeze “Pump Frost Protection [%d °C]” (PondParams) { mqtt="<[broker:piMQTTout/11/6/1/0/0:state:default]" }

Where I get a little lost is with the Setpoint and rules suggestion. So the Setpoint first - I have added the following line to my sitemap file:
Setpoint item=PondFreezeLimit minValue=-1 maxValue=10 step=1
The control appears but the adjustment buttons appear to be disabled/greyed out. At least they do not respond to click attempts (actually neither do the adjustment buttons on the widgets demo frame).

4

Cracked it, I add the solution shortly for anyone else that is interested in this topic

5

OK, so my solution turned out to be very simple actually. Thanks to watou for putting me on the right track.

The first point is that I did not need to create a rule. All was handled within the sitemap and item definition. In my Sitemaps file, I added the following items:
Setpoint item=Pond_Freeze minValue=-1 maxValue=10 step=1
Setpoint item=Pond_Freeze_Hysterisis minValue=0 maxValue=5 step=1

And in the items file I added the following:
Number Pond_Freeze “Pump Frost Protection [%d °C]” (PondParams) { mqtt="<[broker:MQTTout:state:default], >[broker:MQTTin:command::default]" }
Number Pond_Freeze_Hysterisis “Pump Frost Hysterisis [%d °C]” (PondParams) { mqtt="<[broker:MQTTout:state:default], >[broker:MQTTin:command::default]" }

This works very well and is exactly what I wanted. :smile:

1 Like