sendCommand fails with "on instance: null"

Setup, Configuration and Use Beginners
1

Hi.

I am running OH2 version 2.5 on OpenHabian.
I need to re-assign, every 30 minutes, the mode of a KNX Thermostat.
Any help is much appreciated. Details follows.
Greetings from Italy.

I have a number item:

Number  GeneraleClimaUffici  "Clima uffici [%d]"  <heating>   { channel="knx:device:bridge:generic:GeneraleClimaUffici" }

I am trying the following rule

rule "ReassignHVACMode"
when
    Time cron "0 0/30 * 1/1 * ? *"
then
    logInfo("ReassignHVACMode", "GeneraleClimaUffici: " + GeneraleClimaUffici)
    GeneraleClimaUffici.sendCommand(GeneraleClimaUffici.state)
 end

sendCommand fails with “on instance: null” indication.

07:42:14.696 [INFO ] [del.script.---ReassignHVACMode] - GeneraleClimaUffici: GeneraleClimaUffici (Type=NumberItem, State=3, Label=Clima uffici, Category=heating)
07:42:14.714 [ERROR] [untime.internal.engine.RuleEngineImpl] - Rule 'EditGenClimaUffici': An error occurred during the script execution: Could not invoke method: org.eclipse.smarthome.model.script.actions.BusEvent.sendCommand(org.eclipse.smarthome.core.items.Item,java.lang.String) on instance: null
2

It seems to be having some problem with the DecimalType as a command. I think that should work but when all else fails, you can always call toString which will force OH to parse the number to a string and back again which is ineffecient but should bypass the problem.

3

Adding toString solved my problem. Thank you very much Rich!
However, I am unhappy I don’t understand the cause. I will keep this post open for another day.

4

I think the underlying cause is that a state is not a command.
Of course to us, 3.1417 looks the same whether we send it as a state update or a command.
But strictly, GeneraleClimaUffici.state is a state object and does not fall within the allowed commands to a Number type.
By supplying a string instead GeneraleClimaUffici.state.toString we force the core to parse the string into a suitable command type.
I think GeneraleClimaUffici.state as Number should work for the same reason.

You can break it in the same way with
someSwitchItem.sendCommand(otherSwitchItem.state)
because command ON is not the same as state ON etc.

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