Writing Item Value to variable

Setup, Configuration and Use Scripts & Rules
1

Hi,
I need a little bit help writing a rule for switch off heating and turn it an again if window is closed or open.
My try dosn’t work:

/**CONTACT */
rule "BAD EG Fenster offen"
when Item EG_B_CONTACT changed
then
	val EG_B_TEMP = EG_B_ST.value as DecimalType
	if(EG_B_CONTACT.state == OPEN) {
		sendCommand(EG_B_Heat_SW, OFF)
	}
	if(EG_B_CONTACT.state == CLOSED) {
		sendCommand(EG_B_ST, EG_B_TEMP)
	}
end

My Idea is to set the heater to the last value before window was opened. Can anyone give me a hint?
EG_B_ST is an Homematic automatic valve ST is “SetTemperature”

Thanks a lot Christoph

2

Please review

http://docs.openhab.org/configuration/rules-dsl.html

When you have a rule that doesn’t work please:

  1. Load the rules in Designer to check for syntax errors

  2. Post any relevant logs, in particular errors in the logs.

In this case I suspect you are seeing an error saying it can’t parse your .rules file because it has no idea what the heck EG_B_ST.value is. To get the “value” of an Item you use .state.

From a logical perspective the rule doesn’t make sense either. EG_B_TEMP gets set to the current state of EG_B_ST. then if the EG_B_CONTACT is CLOSED your send this same number right back to EG_B_ST. You never actually save the previous value anywhere.

There are two ways you can do this.

First you can move EG_B_TEMP to be a global and populate it when the contact state is OPEN:

var EG_B_TEMP = -1

rule "BAD EG Fenster offen"
when 
    Item EG_B_CONTACT changed
then
	if(EG_B_CONTACT.state == OPEN) {
    	EG_B_TEMP = EG_B_ST.value as Number
		EG_B_Heat.sendCommand(OFF)
	}
	if(EG_B_CONTACT.state == CLOSED) {
		EG_B_ST.sendCommand(EG_B_TEMP)
	}
end

Note: I made some additional changes that makes the code more reliable.

The second way involves persistence which would result in shorter code but I don’t think it will handle the case where someone changes the target temp while the window is open very well.

1 Like
3

Hi Rich, thanks for your reply. I will try to adapt the rule the next few days.
What I missed or not found is a kind of reference or documentation for programming rules.
Http://docs.openhab.org/configuration/rules-dsl.html here are only a few examples listed.

Christoph

4

That link has links to further documentation including to the Xtend language upon which the Rules DSL is based.

5

Solved this issue with persistence.
Here is my solution:

/** BAD EG */                                                                                                                                                                                                      
rule "Heizung Bad EG"                                                                                                                                                                                              
when Item EG_B_Heat_SW changed                                                                                                                                                                                     
then                                                                                                                                                                                                               
        if(EG_B_Heat_SW.state == ON && EG_B_ST.state == 4.5) {                                                                                                                                                     
                EG_B_ST.sendCommand(EG_B_ST.previousState.state as Number)                                                                                                                                         
                logInfo("Testing", "Heizung Bad: AN")                                                                                                                                                              
        }                                                                                                                                                                                                          
        if(EG_B_Heat_SW.state == OFF) {                                                                                                                                                                            
                EG_B_ST.persist                                                                                                                                                                                    
                EG_B_ST.sendCommand("4.5")                                                                                                                                                                         
                logInfo("Testing", "Heizung Bad: AUS")                                                                                                                                                             
        }                                                                                                                                                                                                          
end                                                                                                                                                                                                                
                                                                                                                                                                                                                   
rule "set B_Heat_SW EG"                                                                                                                                                                                            
when Item EG_B_ST changed from 4.5                                                                                                                                                                                 
then                                                                                                                                                                                                               
        EG_B_Heat_SW.sendCommand(ON)                                                                                                                                                                               
end                                                                                                                                                                                                                
                                                                                                                                                                                                                   
/**CONTACT */                                                                                                                                                                                                      
rule "BAD EG Fenster offen"                                                                                                                                                                                        
when Item EG_B_CONTACT changed                                                                                                                                                                                     
then                                                                                                                                                                                                               
        if(EG_B_CONTACT.state == OPEN) {                                                                                                                                                                           
                logInfo("Testing", "Aktueller Status Heizung: " + EG_B_Heat_SW.state)                                                                                                                              
                logInfo("Testing", "Aktueller Wert: " + EG_B_ST.state)                                                                                                                                             
                EG_B_ST.persist                                                                                                                                                                                    
                EG_B_Heat_SW.persist                                                                                                                                                                               
                EG_B_Heat_SW.sendCommand(OFF)                                                                                                                                                                      
        }                                                                                                                                                                                                          
        if(EG_B_CONTACT.state == CLOSED) {                                                                                                                                                                         
                logInfo("Testing", "Letzter Status Heizung: " + EG_B_Heat_SW.previousState.state)                                                                                                                  
                logInfo("Testing", "Letzter Wert: " + EG_B_ST.previousState.state as Number)                                                                                                                       
                EG_B_Heat_SW.sendCommand(EG_B_Heat_SW.previousState.state.toString )                                                                                                                               
                EG_B_ST.sendCommand(EG_B_ST.previousState.state as Number)                                                                                                                                         
        }                                                                                                                                                                                                          
end                                                                                                                                                                                                                
/** Ende BAD EG */